Loading...
3.1.2 -Evidence for the composition of the earth
Quiz by Richard Campbell
Customize this quiz to suit your class
Instantly translate to 100+ languages
Tag the questions with any skills you have. Your dashboard will track each student's mastery of each skill.
Give this quiz to my class
Figure 18-11 represents the amount of energy stored as organic material in each trophic level in an ecosystem. The pyramid shape of the diagram indicates the low percentage of energy transfer from one level to the next. On average, 10 percent of the total energy consumed in one trophic level is incor- porated into the organisms in the next. Why is the percentage of energy transfer so low? One reason is that some of the organisms in a trophic level escape being eaten. They eventually die and become food for decomposers, but the energy contained in their bodies does not pass to a higher trophic level. Even when an organism is eaten, some of the molecules in its body will be in a form that the consumer cannot break down and use. For example, a cougar cannot extract energy from the antlers, hooves, and hair of a deer. Also, the energy used by prey for cellu- lar respiration cannot be used by predators to synthesize new bio- mass. Finally, no transformation or transfer of energy is 100 percent efficient. Every time energy is transformed, such as during the reactions of metabolism, some energy is lost as heat. Limitations of Trophic Levels The low rate of energy transfer between trophic levels explains why ecosystems rarely contain more than a few trophic levels. Because only about 10 percent of the energy available at one trophic level is transferred to the next trophic level, there is not enough energy in the top trophic level to support more levels. Organisms at the lowest trophic level are usually much more abundant than organisms at the highest level. In Africa, for exam- ple, you will see about 1,000 zebras, gazelles, and other herbivores for every lion or leopard you see, and there are far more grasses and shrubs than there are herbivores. Higher trophic levels con- tain less energy, so, they can support fewer individuals.A population is a group of organisms that belong to the same species and live in a particular place at the same time. All of the bass living in a pond during a certain period of time make up a pop- ulation because they are isolated in the pond and do not interact with bass living in other ponds. The boundaries of a population may be imposed by a feature of the environment, such as a lake shore, or they can be arbitrarily chosen to simplify a study of the population. The humans shown in Figure 19-1 are part of the pop- ulation of a city. The properties of populations differ from those of individuals. An individual may be born, it may reproduce, or it may die. A population study focuses on a population as a wholeâhow many individuals are born, how many die, and so on. Population Size A populationâs size is the number of individuals that the population contains. Size is a fundamental and important population property but can be difficult to measure directly. If a population is small and composed of immobile organisms, such as plants, its size can be determined simply by counting individuals. Often, though, individ- uals are too abundant, too widespread, or too mobile to be counted easily, and scientists must estimate the number of individuals in the population. Suppose that a scientist wants to know how many oak trees live in a 10 km2 patch of forest. Instead of searching the entire patch of forest and counting all the oak trees, the scientist could count the trees in a smaller section of the forest, such as a 1 km2 area. The scientist could then use this value to estimate the population of the larger area. SECTION 1 OBJECTIVES â Describe the main properties that scientists measure when they study populations. â Compare the three general patterns of population dispersion. â Identify the measurements used to describe changing populations. â Compare the three general types of survivorship curves. VOCABULARY population population density dispersion birth rate death rate life expectancy age structure survivorship curve FIGURE 19-1 A population can be widely distributed, as Earthâs human population is, or confined to a small area, as species of fish in a lake are. Copyright Š by Holt, Rinehart and Winston. All rights reserved. 382 CHAPTER 19 If the small patch contains 25 oaks, an area 10 times larger would likely contain 10 times as many oak trees. A similar kind of sampling technique might be used to estimate the size of the pop- ulation shown in Figure 19-2. To use this kind of estimate, the sci- entist must assume that the distribution of individuals in the entire population is the same as that in the sampled group. Estimates of population size are based on many such assumptions, so all esti- mates have the potential for error. Population Density Population density measures how crowded a population is. This measurement is always expressed as the number of individuals per unit of area or volume. For example, the population density of humans in the United States is about 30 people per square kilome- ter. Table 19-1 shows the population sizes and densities of humans in several countries in 2003. These estimates are calculated for the total land area. Some areas of a country may be sparsely popu- lated, while other areas are very densely populated. Dispersion A third population property is dispersion (di-SPUHR-zhuhn). Dispersion is the spatial distribution of individuals within the popu- lation. In a clumped distribution, individuals are clustered together. In a uniform distribution, individuals are separated by a fairly con- sistent distance. In a random distribution, each individualâs location is independent of the locations of other individuals in the popula- tion. Figure 19-3 illustrates the three possible patterns of dispersion. Clumped distributions often occur when resources such as food or living space are clumped. Clumped distributions may also occur because of a speciesâ social behavior, such as when animals gather into herds or flocks. Uniform distributions may result from social behavior in which individuals within the same habitat stay as far away from each other as possible. For example, a bird may locate its nest so as to maximize the distance from the nests of other birds. These migrating wildebeests in East Africa are too numerous and mobile to be counted. Scientists must use sampling methods at several locations to monitor changes in the population size of the animals. FIGURE 19-2 TABLE 19-1 Population Size and Density of Some Countries Population size Population density Country (in millions) (in individuals/km2) China 1,289 135 India 1,069 325 United States 292 30 Russia 146 8 Japan 128 337 Mexico 105 54 Kenya 32 54 Australia 20 3 dispersion from the Latin dis-, meaning âout,â and spargere, meaning âto scatterâ Word Roots and Origins Copyright Š by Holt, Rinehart and Winston. All rights reserved. POPULATIONS 383 The social interactions of birds called gannets, which are shown in Figure 19-3b, result in a uniform distribution. Each gannet chooses a small nesting area on the coast and defends it from other gannets. In this way, each gannet tries to maximize its distance from all of its neighbors, which causes a uniform distribution of individuals. Few populations are truly randomly dispersed. Rather, they show degrees of clumping or uniformity. The dispersion pattern of a population sometimes depends on the scale at which the popu- lation is observed. The gannets shown in Figure 19-3b are uni- formly distributed on a scale of a few meters. However, if the entire island on which the gannets live is observed, the distribution appears clumped because the birds live only near the shore. POPULATION DYNAMICS All populations are dynamicâthey change in size and composition over time. To understand these changes, scientists must know more than the populationâs size, density, and dispersion. One important measure is the birth rate, the number of births occur- ring in a period of time. In the United States, for example, there are about 4 million births per year. A second important measure is the death rate, or mortality rate, which is the number of deaths in aMake a multiple choice quiz for my year 8 science students based on the science in this transcript from a video: 3°C 0:04 It can be the difference between snow and sleet 0:08 Wearing a jacket or not 0:11 In your day-to-day life, it may not seem significant 0:15 But 3°C of global warming would be catastrophic 0:20 Heatwaves, droughts, extreme precipitation, even fire 0:25 3°C of warming is really disastrous 0:28 The scary thing is, the world is well on its way there 0:32 Since the industrial revolution, the Earth has warmed between 1.1°C and 1.3°C 0:40 This is a problem that babies you pass in the street will have to live with 0:46 Children born today... 0:47 ...are up to seven times more likely to face extreme weather than their grandparents 0:52 If global temperatures do rise by 3°C... 0:55 ...what would their world look like? Climate change is already having devastating effects 1:03 Rising sea levels 1:05 Desertification 1:07 Hollywood has always enjoyed imagining the end of the world 1:11 While blockbusters like this are clearly fiction... 1:14 ...this film will show the scenario we all face... 1:17 ...unless more drastic measures are taken to stop burning fossil fuels 1:30 In some parts of the world the effects of inaction are already clear 1:35 The slums of Bangladeshâs capital are filling up with climate migrants 1:41 Minara comes from Bhola District, an area in southern Bangladesh 1:46 There, like many other parts of the country... 1:49 ...rivers swollen by heavier rain and melting Himalayan glaciers... 1:53 ...are washing away peopleâs homes 1:56 Many, like her, have lost everything 2:00 Our home in Bhola had endless amounts of land 2:03 There was lots of space for farming, we had a spacious house 2:08 There were different types of fruits, vegetation and trees growing at home 2:12 We used to eat the fruit from our own trees 2:18 I canât eat them now because they don't exist anymore 2:21 Since the river flooded for the third time, I had to flee to Dhaka 2:26 Life was much better back home 2:29 It was unbearable to live through, truly intolerable 2:33 We didnât have the time to save anything at all 2:38 1.1°C to 1.3°C of global warming has already transformed Minaraâs life 2:45 Itâs one of the reasons why so many migrants like her... 2:47 ...are moving to the city each year... 2:50 ...nearly 400,000 according to the last estimate 2:53 And climate models show there could be much worse to come How climate modelling works 3:02 Climate scientist Joeri Rogelj... 3:04 ...has spent the last ten years modelling future climate scenarios... 3:08 ...for the United Nations 3:10 The models we use to carry out this exercise... 3:13 ...really represent the state of the art... 3:15 ...of our current knowledge of climate change and where we are heading 3:19 Joeriâs projections use data collected by hundreds of scientists around the world 3:26 Here this is the 3°C level... 3:28 ...and so there is at least a one-in-four chance that under current policies... 3:32 ...we would hit 3°C by the end of the century 3:36 This is just one of the scenarios Joeri looks at 3:40 Another one imagines that all policy promises are kept 3:44 The most optimistic assumes that all promises have been kept... 3:47 ...and net-zero targets are met 3:50 Where our best estimate ends up around 2°C at the end of the century... 3:54 ...there is still a one-in-20 chance that we end up with 3°C instead 3:59 One would not be entering a plane if there is a one-in-20 chance... 4:03 ...that the plane will crash Nowhere is safe from global warming 4:07 A rise of 3°C would affect everyone 4:10 Even wealthy cities in rich countries wouldnât be immune to the consequences 4:15 European capitals like Paris and Berlin... 4:18 ...would bake under more extreme heatwaves 4:22 Frequent storm-surges in New York could turn parts of the city desolate 4:27 In many ways, cities magnify, intensify climate events 4:33 Cities are hotter than the places around them... 4:36 ...they tend to be more vulnerable to flooding 4:39 And you can get a really bad event in a city in a way that you canât in the countryside 4:46 And because of their denser populations... 4:49 ...disasters in a city affect far more people 4:52 Some cities might be badly prepared for the changes coming 4:56 But they have the means to adapt 4:59 Cities tend to be wealthier than surrounding places 5:03 They have a lot of amenities 5:05 A city that has taken seriously the risks of a 3°C world... 5:08 âŚwouldnât necessarily be a worse place to be in a 3°C world 5:12 But a city that hasnât prepared for these sort of eventualities... 5:16 ...that might be a really nasty place The impact of prolonged droughts 5:20 So far, many developed cities have got off lightly... 5:24 ...but some rural parts of the world are suffering disproportionately 5:29 Smallholdersâsmall-scale farmersâare particularly vulnerable to climate change 5:35 And there are over 600 million around the world 5:38 Smallholders with farms under two hectares... 5:40 ...produce around a third of the global food supply 5:46 Central Americaâs âDry Corridorâ... 5:48 ...supports a mix of smallholdings and medium-sized farms 5:53 Sandwiched between the Pacific Ocean and the Caribbean Sea... 5:56 ...the area is prone to droughts 6:08 Israel RamĂrez Rivera is a smallholder in Guatemala 6:12 Here, climate change is making the dry seasons longer, and more severe 6:18 This is the biggest ear of maize that this plot could deliver 6:23 He depends on his crops of corn and beans 6:26 But theyâre getting harder to grow 6:30 The surrounding mountains... 6:32 ...used to provide us with native food... 6:38 ...and now that isnât an option anymore... 6:41 ...due to climate change and its effects 6:46 Nearly two-thirds of the smallholders in the Dry Corridor now live in poverty 6:52 The impact of all of this for us... 6:59 ...malnutrition among children 7:03 Weâve lost a few 7:07 For my crops especially, the midsummer heat is harder than before 7:16 The plant dries up and canât provide us... 7:19 ...with the necessary food provision 7:24 Severe droughts in Central America... 7:26 ...are now four times more likely than they were last century 7:30 Many families from here have gone to the States 7:37 The economic despair and debts... 7:44 ...have pushed many people from this community to do this journey 7:53 Migration from Guatemala to the United States has quadrupled since 1990 7:59 Not all of this has been due to climate change 8:02 But longer droughts would force even more to move 8:05 In a 3°C world, annual rainfall in this region... 8:09 ...could drop by up to 14% 8:12 At 3°C, over a quarter of the worldâs population... 8:16 ...could endure extreme droughts for at least a month of the year 8:19 Northern Africa could see droughts that last for years at a time Rising sea levels, storm surges and flooding 8:24 But for some, too much water will be the problem 8:29 10% of the worldâs population lives on a coastline... 8:32 ...thatâs less than 10 metres above sea level 8:35 For these coastal inhabitants, a 3°C world would spell disaster 8:40 By 2100, global sea levels could have climbed by half a metre from 2005 levels 8:46 Low-lying cities like Lagos would be especially vulnerable... 8:49 ...with up to up to a third of the population displaced 8:54 And in Fiji, rising waters are already upending lives 9:04 You can see the graveyard there, itâs all under water now... 9:08 ...due to this rising sea level and climate change 9:15 The village of Togoru in Fiji is being swallowed by the sea 9:19 Barney Dunn, the village headman, has seen over half the village disappear 9:24 Relativesâ houses have been abandoned, and family graves are now under water 9:29 We have been asked by the government to relocate... 9:32 ...but no one wants to relocate... 9:34 ...because we have our great-great-grandparents down there in the sea 9:39 This is the place weâve been brought up in 9:41 ...itâs not easy to leave 9:44 Past attempts to build a seawall havenât worked 9:48 But Barney sees building a new one as the villageâs only hope 9:52 If they do that, maybe we can save whatever is left 9:56 But if we donât have the seawall, then it will be keep eroding and time will come... 10:01 ...maybe in ten,15 years, Togoru will be all eroded 10:05 Rising seas also mean storms cause more floods 10:11 And many more countries could suffer 10:14 The Philippines and Myanmar are just two countries... 10:17 ...that will also see an increase in storm surges in a 3°C world 10:21 To escape, many will move⌠10:24 âŚoften, to urban areas Extreme heat and wet-bulb temperatures 10:27 Half the worldâs population already lives in cities... 10:31 ...almost a third in slums 10:36 For them, a 3°C world could be deadly 10:40 Minara has moved to Dhaka to escape the impact of climate change 10:44 But life could get even worse for her 10:47 Iâm struggling a lot nowadays 10:49 The heat during the day is unbearable 10:52 Even late at night it doesnât cool down 10:57 The heat is getting more intense every day 10:59 I mean, itâs going to get much worse 11:03 I can barely survive it now, how will I live through it in the future? 11:08 Dhaka is getting hotter 11:11 In the last 20 years the average daytime temperature... 11:13 ...has crept up by nearly half a degree 11:17 Days that approach 40°C are now being reported 11:20 And high so-called wet-bulb temperatures are on the rise 11:26 A wet-bulb temperature is a measure of heat and humidity 11:30 Humans cool themselves by sweating⌠11:32 But in these conditions, when relative humidity is near 100%... 11:36 ...sweat doesnât evaporate well 11:38 So people canât cool down⌠11:41 ...even if given unlimited shade and water 11:45 At a high wet-bulb temperature, the body canât lose heat... 11:49 ...and so it gets hotter and hotter... 11:51 ...and the body is designed to work at a given temperature 11:53 And if it gets too hot inside, you will die 11:58 The human limit for wet-bulb temperatures is 35°C... 12:02 ...around skin temperature 12:04 Dhaka will have a much higher chance... 12:05 ...of reaching dangerous wet-bulb temperatures... 12:07 ...if global warming reaches 3°C 12:12 You canât really adapt to that 12:14 You have to get out. If the temperature is so high that you canât work... 12:20 ...canât do hard manual labour outside for significant parts of the year... 12:25 ...then many places will become functionally no longer part of the economy 12:33 Jacobabad in Pakistan, and Ras al Khaimah, in the United Arab Emirates... 12:37 ...have already recorded deadly wet-bulb temperatures 12:40 More of the tropics and the Persian Gulf... 12:43 ...as well as parts of Mexico and the south-eastern United States... 12:47 ...could all get to this threshold by the end of the century 12:50 Climate modelling might show us the weather Increased migration and conflict 12:52 But it doesnât show us its other effects on society 12:56 Established migration patterns could change 12:59 Climate disasters may exacerbate reasons people cross borders 13:03 Within countries, more people will move to cities 13:07 In a 3°C world, tens of millions of people a year... 13:10 ...could be displaced by disasters made worse by climate change 13:15 When people are displaced by climate... 13:18 âŚthey may well go to cities... 13:19 ...because cities are the places that attract people from the countryside already 13:25 A lot of people who can get to the developed world... 13:28 ...not least because the developed world tends to be less hot, will give that a go 13:35 As migration around the world increases... 13:38 ...there could be more competition for fewer resources 13:42 Waterâalready a highly contested resourceâwill be a focal point 13:47 Turkeyâs new Ilisu dam has reduced the flow of water into Iraq 13:53 China lays claim to rivers vital to India and Pakistan 13:57 The prospect of a water-conflict makes people very uneasy 14:03 How national tensions would exacerbate those sorts of reactions... 14:08 ...in a 3°C world... 14:09 ...is the sort of thing that no one should really want to find out 14:14 I think youâd have to be incredibly sanguine... 14:16 ...not to think that the sort of climate extremes that we talk about... 14:19 ...in a 3°C world wouldnât lead some places... 14:22 ...to the brink of societal collapse 14:25 Those lucky enough to escape unrest... Adaptation and mitigation are crucial 14:28 ...would still have to adapt to a radically different world 14:32 People can adapt to climate change in all sorts of ways, one of the most obvious ones... 14:37 ...is air conditioning 14:39 But other ways to adapt at a local or regional level... 14:42 ...I mean, one of the most obvious is diversifying agriculture 14:47 There are physical things you can do, like seawalls 14:52 The fact that people can adapt and that adaptation will reduce suffering... 14:57 ...doesnât mean that it will eliminate suffering 15:00 Suffering is built into this whole process of heating up the planet 15:06 Adaptation will only get the world so far 15:09 The best way to deal with a 3°C world... 15:12 ...is not to go to a 3°C world 15:14 And thatâs why increasing efforts on mitigation are important 15:17 Itâs why working towards negative emissions... 15:20 ...that could bring down the temperature after it peaks are important 15:25 Once you get to a 3°C world, you are in real bad global trouble 15:33 The scale of change needed... 15:35 ...and the slow progress of governments so far... 15:38 ...means 3°C of warming is uncomfortably likely unless more is done 15:44 Despite existing pledges, greenhouse-gas emissions... 15:48 ...are still set to rise by 16% from 2010 levels by 2030 15:54 The need to act has never been clearer 15:57 Thereâs still time to reduce emissions, so that a 3°C world remains fiction... 16:02 ...rather than becoming factCovalent Molecules and Compounds Just as an atom is the simplest unit that has the fundamental chemical properties of an element, a molecule is the simplest unit that has the fundamental chemical properties of a covalent compound. Some pure elements exist as covalent molecules. Hydrogen, nitrogen, oxygen, and the halogens occur naturally as the diatomic (âtwo atomsâ) molecules H2, N2, O2, F2, Cl2, Br2, and I2 (part (a) in Figure 3.1.1). Similarly, a few pure elements exist as polyatomic (âmany atomsâ) molecules, such as elemental phosphorus and sulfur, which occur as P4 and S8 (part (b) in Figure 3.1.1). Each covalent compound is represented by a molecular formula, which gives the atomic symbol for each component element, in a prescribed order, accompanied by a subscript indicating the number of atoms of that element in the molecule. The subscript is written only if the number of atoms is greater than 1. For example, water, with two hydrogen atoms and one oxygen atom per molecule, is written as H2O. Similarly, carbon dioxide, which contains one carbon atom and two oxygen atoms in each molecule, is written as CO2. Covalent compounds that predominantly contain carbon and hydrogen are called organic compounds. The convention for representing the formulas of organic compounds is to write carbon first, followed by hydrogen and then any other elements in alphabetical order (e.g., CH4O is methyl alcohol, a fuel). Compounds that consist primarily of elements other than carbon and hydrogen are called inorganic compounds; they include both covalent and ionic compounds. In inorganic compounds, the component elements are listed beginning with the one farthest to the left in the periodic table, as in CO2 or SF6. Those in the same group are listed beginning with the lower element and working up, as in ClF. By convention, however, when an inorganic compound contains both hydrogen and an element from groups 13â15, hydrogen is usually listed last in the formula. Examples are ammonia (NH3) and silane (SiH4). Compounds such as water, whose compositions were established long before this convention was adopted, are always written with hydrogen first: Water is always written as H2O, not OH2. The conventions for inorganic acids, such as hydrochloric acid (HCl) and sulfuric acid (H2SO4), are described elswhere. Note! For organic compounds: write C first, then H, and then the other elements in alphabetical order. For molecular inorganic compounds: start with the element at far left in the periodic table; list elements in same group beginning with the lower element and working up. Write the molecular formula of each compound. a. The phosphorus-sulfur compound that is responsible for the ignition of so-called strike anywhere matches has 4 phosphorus atoms and 3 sulfur atoms per molecule. b. Ethyl alcohol, the alcohol of alcoholic beverages, has 1 oxygen atom, 2 carbon atoms, and 6 hydrogen atoms per molecule. c. Freon-11, once widely used in automobile air conditioners and implicated in damage to the ozone layer, has 1 carbon atom, 3 chlorine atoms, and 1 fluorine atom per molecule. Solution: a. ⢠A The molecule has 4 phosphorus atoms and 3 sulfur atoms. Because the compound does not contain mostly carbon and hydrogen, it is inorganic. ⢠B Phosphorus is in group 15, and sulfur is in group 16. Because phosphorus is to the left of sulfur, it is written first. ⢠C Writing the number of each kind of atom as a right-hand subscript gives P4S3 as the molecular formula. b. ⢠A Ethyl alcohol contains predominantly carbon and hydrogen, so it is an organic compound. ⢠B The formula for an organic compound is written with the number of carbon atoms first, the number of hydrogen atoms next, and the other atoms in alphabetical order: CHO. ⢠C Adding subscripts gives the molecular formula C2H6O. c. ⢠A Freon-11 contains carbon, chlorine, and fluorine. It can be viewed as either an inorganic compound or an organic compound (in which fluorine has replaced hydrogen). The formula for Freon-11 can therefore be written using either of the two conventions. ⢠B According to the convention for inorganic compounds, carbon is written first because it is farther left in the periodic table. Fluorine and chlorine are in the same group, so they are listed beginning with the lower element and working up: CClF. Adding subscripts gives the molecular formula CCl3F. ⢠C We obtain the same formula for Freon-11 using the convention for organic compounds. The number of carbon atoms is written first, followed by the number of hydrogen atoms (zero) and then the other elements in alphabetical order, also giving CCl3F. Write the molecular formula for each compound. a. Nitrous oxide, also called âlaughing gas,â has 2 nitrogen atoms and 1 oxygen atom per molecule. Nitrous oxide is used as a mild anesthetic for minor surgery and as the propellant in cans of whipped cream. b. Sucrose, also known as cane sugar, has 12 carbon atoms, 11 oxygen atoms, and 22 hydrogen atoms. c. Sulfur hexafluoride, a gas used to pressurize âunpressurizedâ tennis balls and as a coolant in nuclear reactors, has 6 fluorine atoms and 1 sulfur atom per molecule. Answer: a. N2O b. C12H22O11 c. SF6. Ionic Compounds The substances described in the preceding discussion are composed of molecules that are electrically neutral; that is, the number of positively-charged protons in the nucleus is equal to the number of negatively-charged electrons. In contrast, ions are atoms or assemblies of atoms that have a net electrical charge. Ions that contain fewer electrons than protons have a net positive charge and are called cations. Conversely, ions that contain more electrons than protons have a net negative charge and are called anions. Ionic compounds contain both cations and anions in a ratio that results in no net electrical charge. Note! Ionic compounds contain both cations and anions in a ratio that results in zero electrical charge.An ionic compound that contains only two elements, one present as a cation and one as an anion, is called a binary ionic compound. One example is MgCl2, a coagulant used in the preparation of tofu from soybeans. For binary ionic compounds, the subscripts in the empirical formula can also be obtained by crossing charges: use the absolute value of the charge on one ion as the subscript for the other ion. This method is shown schematically as follows: Crossing charges. One method for obtaining subscripts in the empirical formula is by crossing charges. When crossing charges, it is sometimes necessary to reduce the subscripts to their simplest ratio to write the empirical formula. Consider, for example, the compound formed by Mg2+ and O2â. Using the absolute values of the charges on the ions as subscripts gives the formula Mg2O2:Polyatomic Ions Polyatomic ions are groups of atoms that bear net electrical charges, although the atoms in a polyatomic ion are held together by the same covalent bonds that hold atoms together in molecules. Just as there are many more kinds of molecules than simple elements, there are many more kinds of polyatomic ions than monatomic ions. Two examples of polyatomic cations are the ammonium (NH4+) and the methylammonium (CH3NH3+) ions. P. The method used to predict the empirical formulas for ionic compounds that contain monatomic ions can also be used for compounds that contain polyatomic ions. The overall charge on the cations must balance the overall charge on the anions in the formula unit. Thus, K+ and NO3â ions combine in a 1:1 ratio to form KNO3 (potassium nitrate or saltpeter), a major ingredient in black gunpowder. Similarly, Ca2+ and SO42â form CaSO4 (calcium sulfate), which combines with varying amounts of water to form gypsum and plaster of Paris. The polyatomic ions NH4+ and NO3â form NH4NO3 (ammonium nitrate), a widely used fertilizer and, in the wrong hands, an explosive. One example of a compound in which the ions have charges of different magnitudes is calcium phosphate, which is composed of Ca2+ and PO43â ions; it is a major component of bones. The compound is electrically neutral because the ions combine in a ratio of three Ca2+ ions [3(+2) = +6] for every two ions [2(â3) = â6], giving an empirical formula of Ca3(PO4)2; the parentheses around PO4 in the empirical formula indicate that it is a polyatomic ion. Writing the formula for calcium phosphate as Ca3P2O8 gives the correct number of each atom in the formula unit, but it obscures the fact that the compound contains readily identifiable PO43â ions.Summary ⢠There are two fundamentally different kinds of chemical bonds (covalent and ionic) that cause substances to have very different properties. ⢠The composition of a compound is represented by an empirical or molecular formula, each consisting of at least one formula unit.Contributors The atoms in chemical compounds are held together by attractive electrostatic interactions known as chemical bonds. Ionic compounds contain positively and negatively charged ions in a ratio that results in an overall charge of zero. The ions are held together in a regular spatial arrangement by electrostatic forces. Most covalent compounds consist of molecules, groups of atoms in which one or more pairs of electrons are shared by at least two atoms to form a covalent bond. The atoms in molecules are held together by the electrostatic attraction between the positively charged nuclei of the bonded atoms and the negatively charged electrons shared by the nuclei. The molecular formula of a covalent compound gives the types and numbers of atoms present. Compounds that contain predominantly carbon and hydrogen are called organic compounds, whereas compounds that consist primarily of elements other than carbon and hydrogen are inorganic compounds. Diatomic molecules contain two atoms, and polyatomic molecules contain more than two. A structural formula indicates the composition and approximate structure and shape of a molecule. Single bonds, double bonds, and triple bonds are covalent bonds in which one, two, and three pairs of electrons, respectively, are shared between two bonded atoms. Atoms or groups of atoms that possess a net electrical charge are called ions; they can have either a positive charge (cations) or a negative charge (anions). Ions can consist of one atom (monatomic ions) or several (polyatomic ions). The charges on monatomic ions of most main group elements can be predicted from the location of the element in the periodic table. Ionic compounds usually form hard crystalline solids with high melting points. Covalent molecular compounds, in contrast, consist of discrete molecules held together by weak intermolecular forces and can be gases, liquids, or solids at room temperature and pressure. An empirical formula gives the relative numbers of atoms of the elements in a compound, reduced to the lowest whole numbers. The formula unit is the absolute grouping represented by the empirical formula of a compound, either ionic or covalent. Empirical formulas are particularly useful for describing the composition of ionic compounds, which do not contain readily identifiable molecules. Some ionic compounds occur as hydrates, which contain specific ratios of loosely bound water molecules called waters of hydration.A solution is a mixture in which one or more substances are uniformly distributed in another substance. Solutions can be mixtures of liquids, solids, or gases. For example, plasma, the liquid part of blood, is a very complex solution. It is composed of many types of ions and large molecules, as well as gases, that are dissolved in water. A solute (SAHL-YOOT) is a substance dissolved in the solvent. The particles that compose a solute may be ions, atoms, or molecules. The solvent is the substance in which the solute is dissolved. For example, when sugar, a solute, and water, a solvent, are mixed, a solution of sugar water results. Though the sugar dissolves in the water, neither the sugar molecules nor the water molecules are altered chemically. If the water is boiled away, the sugar molecules remain and are unchanged. Solutions can be composed of various proportions of a given solute in a given solvent. Thus, solutions can vary in concentra- tion. The concentration of a solution is the amount of solute dis- solved in a fixed amount of the solution. For example, a 2 percent saltwater solution contains 2 g of salt dissolved in enough water to make 100 mL of solution. The more solute dissolved, the greater is the concentration of the solution. A saturated solution is one in which no more solute can dissolve. Aqueous (AY-kwee-uhs) solutionsâsolutions in which water is the solventâare universally important to living things. Marine microorganisms spend their lives immersed in the sea, an aqueous solution. Most nutrients that plants need are in aqueous solutions in moist soil. Body cells exist in an aqueous solution of intercellu- lar fluid and are themselves filled with fluid; in fact, most chemical reactions that occur in the body occur in aqueous solutions. Copyright Š by Holt, Rinehart and Winston. All rights reserved. Liquid water Solid water Ice (solid water) is less dense than liquid water because of the structure of ice crystals. The water molecules in ice are bonded to each other in a way that creates large amounts of open space between the molecules, relative to liquid water. FIGURE 2-12 solvent from the Latin solvere, meaning âto loosenâ Word Roots and Origins CHEMISTRY OF LIFE 43 ACIDS AND BASES One of the most important aspects of a living system is the degree of its acidity or alkalinity. What do we mean when we use the terms acid and base? Ionization of Water As water molecules move about, they bump into one another. Some of these collisions are strong enough to result in a chemical change: one water molecule loses a proton (a hydrogen nucleus), and the other gains this proton. This reaction really occurs in two steps. First, one molecule of water pulls apart another water molecule, or dissociates, into two ions of opposite charge: H2O â H OH The OH ion is known as the hydroxide ion. The free H ion can react with another water molecule, as shown in the equation below. H H2O â H3O The H3O ion is known as the hydronium ion. Acidity or alkalin- ity is a measure of the relative amounts of hydronium ions and hydroxide ions dissolved in a solution. If the number of hydronium ions in a solution equals the number of hydroxide ions, the solution is said to be neutral. Pure water contains equal numbers of hydro- nium ions and hydroxide ions and is therefore a neutral solution. Acids If the number of hydronium ions in a solution is greater than the number of hydroxide ions, the solution is an acid. For example, when hydrogen chloride gas, HCl, is dissolved in water, its mol- ecules dissociate to form hydrogen ions, H, and chloride ions, Cl, as is shown in the equation below. HCl â H Cl These free hydrogen ions combine with water molecules to form hydronium ions, H3O. This aqueous solution contains many more hydronium ions than it does hydroxide ions, making it an acidic solution. Acids tend to have a sour taste; how- ever, never taste a substance to test it for acidity. In concentrated forms, they are highly corrosive to some materials, as you can see in Figure 2-13. Bases If sodium hydroxide, NaOH, a solid, is dissolved in water, it dissociates to form sodium ions, Na, and hydroxide ions, OH, as shown in the equation below. NaOH â Na OH Copyright Š by Holt, Rinehart and Winston. All rights reserved. Eco Connection onnection Acid Precipitation Acid precipitation, more commonly called acid rain, describes rain, snow, sleet, or fog that contains high levels of sulfuric and nitric acids. These acids form when sulfur dioxide gas, SO2, and nitrogen oxide gas, NO, react with water in the atmosphere to produce sulfuric acid, H2SO4, and nitric acid, HNO3. Acid precipitation makes soil and bodies of water, such as lakes, more acidic than normal. These high acid levels can harm plant and animal life directly. A high level of acid in a lake may kill mollusks, fish, and amphibians. Even in a lake that does not have a very elevated level of acid, acid precipitation may leach aluminum and magnesium from soils, poisoning water- dwelling species. Reducing fossil-fuel consump- tion, such as occurs in gasoline engines and coal-burning power plants, should reduce high acid levels in precipitation. Sulfur dioxide, SO2, which is produced when fossil fuels are burned, reacts with water in the atmosphere to produce acid precipitation. Acid precipitation, or acid rain, can make lakes and rivers too acidic to support life and can even corrode stone, such as the face of this statue. FIGURE 2-13 44 CHAPTER 2 This solution then contains more hydroxide ions than hydronium ions and is therefore defined as a base. The adjective alkaline refers to bases. Bases have a bitter taste; however, never taste a substance to test for alkalinity. They tend to feel slippery because the OH ions react with the oil on our skin to form a soap. In fact, commercial soap is the product of a reaction between a base and a fat. pH Scientists have developed a scale for comparing the relative con- centrations of hydronium ions and hydroxide ions in a solution. This scale is called the pH scale, and it ranges from 0 to 14, as shown in Figure 2-14. A solution with a pH of 0 is very acidic, a solution with a pH of 7 is neutral, and a solution with a pH of 14 is very basic. A solutionâs pH is measured on a logarithmic scale. That is, the change of one pH unit reflects a 10-fold change in the acidity or alkalinity. For example, urine has 10 times the H3O ions at a pH of 6 than water does at a pH of 7. Vinegar, has 1,000 times more H3O ions at a pH of 3 than urine at a pH of 6, and 10,000 times more H3O ions than water at a pH of 7. The pH of a solution can be measured with litmus paper or with some other chemical indicator that changes color at various pH levels. Buffers The control of pH is important for living systems. Enzymes can function only within a very narrow pH range. The control of pH in organisms is often accomplished with buffers. Buffers are chemi- cal substances that neutralize small amounts of either an acid or a base added to a solution. As Figure 2-14 shows, the composition of your internal environmentâin terms of acidity and alkalinityâ varies greatly. Some of your body fluids, such as stomach acid and urine, are acidic. Others, such as intestinal fluid and blood, areThe Pleiades, also known as the Seven Sisters, is a famous star cluster located in the constellation of Taurus. It is made up of a group of seven bright stars that are visible to the naked eye in the night sky. The stars in the Pleiades cluster are relatively young, being only about 100 million years old, which is young in astronomical terms. The Pleiades cluster has been observed and admired by cultures all around the world for thousands of years. In Greek mythology, the Pleiades were seven sisters who were pursued by the hunter Orion. To protect them, Zeus transformed them into stars, forming the star cluster we see today. Different cultures have their own stories and legends associated with the Pleiades, making it a fascinating object of study for astronomers and a source of inspiration for artists and storytellers. The Pleiades cluster is often used as a test of eyesight, as people are challenged to count how many stars they can see with the naked eye. Most people can see six or seven stars, but those with particularly sharp vision may be able to see more. The Pleiades is also a popular target for amateur astronomers with telescopes, as the cluster reveals even more stars and details when viewed through a telescope. In addition to being a beautiful sight in the night sky, the Pleiades cluster also serves a practical purpose for astronomers. By studying the stars in the Pleiades, scientists can learn more about how stars form and evolve, as well as gain insights into the structure and composition of the Milky Way galaxy. The Pleiades cluster continues to be an important object of study for astronomers, both amateur and professional, and its beauty and significance will continue to capture the imaginations of people for generations to come. Matariki is the Maori name for the Pleiades star cluster. The Pleiades is a group of stars that can be seen in the night sky, and Matariki is a special time of year when the star cluster is visible in the sky. In Maori culture, Matariki is seen as the beginning of the Maori New Year, and it is a time to celebrate and give thanks for the past year and look forward to the year ahead. So basically, Matariki is related to the Pleiades because it is a special time of year when those stars are visible in the sky and it has cultural significance for the Maori people. The Pleiades star cluster is known by different names in various cultures around the world. Here are some of the names by which the Pleiades are referred to in different countries: 1. Maori culture in New Zealand and Polynesia: Matariki 2. Greek mythology: The Seven Sisters 3. Japan: Subaru 4. Native American tribes: The Dancers or The Little Eyes 5. Inca civilization: Collca 6. Ancient Persia: Parvin 7. India: Krittika 8. Aboriginal Australians: The Seven Sisters or Djulpan These different names reflect the diverse cultural significance and interpretations of the Pleiades cluster in various societies throughout history.What Is Rhythm in Music? Rhythm is the pattern of sound, silence, and emphasis in a song. In music theory, rhythm refers to the recurrence of notes and rests (silences) in time. When a series of notes and rests repeats, it forms a rhythmic pattern. In addition to indicating when notes are played, musical rhythm also stipulates how long they are played and with what intensity. This creates different note durations and different types of accents.Why Is Rhythm Important in Music? Rhythm functions as the propulsive engine of a piece of music, and it gives a composition structure. Most musical ensembles contain a rhythm section responsible for providing the rhythmic backbone for the entire group. Drums, percussion, bass, guitar, piano, and synthesizer may all be considered rhythm instruments, depending on the context. However, all members of a music group bear responsibility for their own rhythmic performances and play the musical beats and rhythmic patterns indicated by the piece's composer.7 Elements of Rhythm in Music Several core elements comprise the fundamentals of musical rhythm. 1. Time signature: A musical time signature indicates the number of beats per measure. It also indicates how long these beats last. In a time signature with a 4 on the bottom (such as 2/4, 3/4, 4/4, 5/4, etc.), a beat corresponds with a quarter note. So in a 4/4 time (also known as "common time"), each beat is the length of a quarter note, and every four beats form a full measure. In 5/4 time, every five beats form a full measure. In a time signature with an 8 on the bottom (such as 3/8, 6/8, or 9/8), a beat corresponds with an eighth note. 2. Meter: Standard Western music theory divides time signatures into three types of musical meter: duple meter (where beats appear in groups of two), triple meter (where beats appear in groups of three), and quadruple meter (where beats appear in groups of four). Meter is not tied to note values; for instance, a triple meter could involve three half notes, three quarter notes, three eighth notes, three sixteenth notes, or three notes of any duration. Musicians and composers regularly mix duple and triple meter in their work; Igor Stravinsky's "The Rite of Spring" is a textbook example of such a technique. 3. Tempo: Tempo is the speed at which a piece of music is played. There are three primary ways that tempo is communicated to players: beats per minute, Italian terminology, and modern language. Beats per minute (or BPM) indicates the number of beats in one minute. Certain Italian words like largo, andante, allegro, and presto convey tempo change by describing the speed of the music. Finally, some composers indicate tempo with casual English words such as âfast,â âslow,â âlazy,â ârelaxed,â and âmoderate.â 4. Strong beats and weak beats: Rhythm combines strong beats and weak beats. Strong beats include the first beat of each measure (the downbeat), as well as other heavily accented beats. Both popular music and classical music combine strong beats and weak beats to create memorable rhythmic patterns. 5. Syncopation: Syncopated rhythms are those that do not align with the downbeats of individual measures. A syncopated beat will put its emphasis on traditional weak beats, such as the second eighth note in a measure of 4/4. Complex rhythms tend to include syncopation. While these rhythms may be more difficult for a beginning musician to pick up, they tend to sound more striking than non-syncopated rhythmic patterns. 6. Accents: Accents refer to special emphases on certain beats. To understand accents, think of a piece of poetry. A poetic meter, such as iambic pentameter, may dictate a specific mixture of stressed syllables and unstressed syllables. Musical accents are no different. Different rhythms may share a time signature and tempo, but they stand out from one another by accenting different notes and beats. 7. Polyrhythms: To achieve a particularly ambitious sense of rhythm, an ensemble may employ polyrhythm, which layers one type of rhythm on top of another. For instance, a salsa percussion ensemble may feature congas and bongos playing 4/4 time, while the timbales concurrently play a pattern in 3/8. This creates a dense rhythmic stew and, when properly executed, it can yield incredibly danceable rhythm patterns. Polyrhythms originated in African drumming, and theyâve spread to all sorts of genres worldwide, from Afro-Caribbean to Indian to progressive rock, jazz, and contemporary classical.A piece thatâs sung as opposed to played. Answer: Cantata A hymn tune of the Lutheran church. Answer: Chorale A part for keyboard (harpsichord or organ) and cello or bass. The keyboard player reads the cello line and provides an accompaniment based on the figured Bass. Answer: Basso continuo The numbers written under the cello part indicating chords and their positions to the keyboard player. Answer: Figured Bass A piece for choir. Answer: Chorus A style of singing that is more related in pitch and rhythm to speech than song. In the 18th Century it was used extensively in Opera as âDialogueâ between Characters. Answer: Recitative (Dry) Accompanied only by continuo. Answer: Recitativo secco More expressive and accompanied by the orchestra. Answer: Recitativo stromentato Contrapuntal device whereby a motif or phrase is presented successively by different voices. Answer: Imitation To turn a motif or phrase âup-side downâ. Answer: Inversion A song for 1 or more voices, popular in Opera and Cantata as a contrast with Recitative. Answer: Aria A type of piece that was written as a set of variations on an Ostinato. Answer: Chaconne A musical idea repeating many times. Answer: Ostinato A sustained or repeated note over which the harmonies change. Answer: Pedal Point Point of rest. Answer: Cadence Change of key. Answer: Modulation Where the composer gives prominence or illustrates words in musical terms. Answer: Word Painting A motif that has more than 1 note per syllable is said to be melismatic. Often used as word painting. Answer: Melisma Where 1 note per syllable is used. Answer: Syllabic A polyphonic composition in which a part is imitated by 1 or more parts so that successive statements of the melody overlap. Answer: Canon Any rhythmically independent movement between parts. Answer: Polyphony A combination of 2 or more independent melodies. Answer: Counterpoint A structure consisting of 3 sections-ABA. Answer: Ternary Form Back to the beginning as in the Da Capo Aria. Answer: Da Capo (D.C.) Back to the sign. Answer: Dal Segno (D.S.) A motif which is repeated at a different pitch in the same part. Answer: SequenceChapter One: Management Today The challenges of working in the new economy recognize: 1.1 Working Today Talent Talented people- What they know, what they learn and what they can achive The source of organisational performance Develop skills and improve What is intellectual capital The combined brain power and shared knowledge of an organization's employees TO orginzations: Intellectual capital resents a strategic asset as human creativity, insight and decision making can be converted into superior performance To individuals: Intellectual capital is a personal asset, one to be nurtured and continually updated Things evolve, make sure we keep updated Intellectual capital: The package on intellect skills and capabilities that set us apart making us valable to potential employers Maintaining your talent: There is no escaping the fact that your career success will require a lot of initiative, self awareness and continuous learning Technology Tech is in our everyday lives Latest developments Smart phone, smart apparel, smart cars, smart homes We struggle to keep up with social media ana staying connected with messaging, full of email and voicemail What happenings as younger workers advance into management Flexibility Work ethic It is critical to build and maintain a high Tech IQ! What is Tech IQ: The ability to use current technologies at work and in your personal life, combined with the commitment to keep yourself updated as technology continues to evolve Intellectual capi5la is a combination of: Commitment x Competency = Intellectual capital How to make the world a better place Globalisation The worldwide interdependence of resources flows, product markets and business competition Under the influence, government leaders worry and about the competitiveness of nations just as corporate leaders worry about business competitiveness Emerging markets will power global growth over the next 20 years. By 2025 overall global consumption is forecast to reach $62 trillion, twice its 2013 level and fully half of this increase will come from the emerging world Consequence: Going to fast in uses resources, inflation, corporate greed It's cheaper to have things made in different countries (wages are low and going down) Shamrock organization 1 leaf - full time employees- standard career paths 2 leaf - âfreelancersâ 3 leaf - Part times without benefits (first to lose their jobs when employers face economic difficulties) The rising of emerging markets Now account for 60% of all low and medium technology manufacturing worldwide Total value add in high tech manufacturing from a low 26% in the 1970s to 48% at present China strategy to upgrade its industries and move the manufacturing value ching by prioritising 10 sectors Information technology, robotic, aerospace, maritime equipment, modern railway equipment, alternative energy vehicles, power equipment, agriculture equipment, advanced materials, biopharma and medical products Ethics A code of moral principa;s that sets standards for conduct that is âgoodâ and ârightâ as well as âbadâ and âwrongâ Enron company huge corruption even in elections same thing happened with The Mechanism 1.2 - Organizations Organizational Purpose An orgnizations is a collection of people working together to achieve a common purpose Unique social phenomenon that enables its members to perform tasks far beyond the reach of individual accomplishment (synergy) The broad purpose of any orginzation is to provide goods or services of value to customers and clients A clear sense of purpose tied to: Quality of products and services Customer satisfaction Social responsibility Can be an important source of organisational strength and performance advantage All organisations are open systems (Systems that interact with its environment for renewal and growth) Organizations as systems All organizations are open systems that interact with their environment Continual process of obtaining resource inputs-people, information, resources and capital- and transforming them into outputs in the form of finished goods and services for customers One simple way to assess the impact of any organisation is to ask the question: How is the world different because it existed Value Creation: Organisations create value when they use resources well to produce good products and take care of their customers One simple way to assess the impact of any organization is to ask the questions: How is the world different because it existed? The 3 Ps of organizational performance Profit - is the decision economically sound? People - Does the decision treat people with respect and dignity? Planet - Is the decision good for the environment? Productivity: An overall measure of the quantity and quality of work performance with recourse utilisation taken into account Performance effectiveness: An output measure of task or goal accomplishment Performance efficiency: An input measure of the resource costs associated with goal accomplishment. Workplace changes that impact management Focus on valuing human capital Demise of âCommand and controlâ Emphasis on teamwork Pre-eminence of technology New workforce expectations Importance of networking Concern for sustainability 1.3 Managers Importance of human resources and manger People are not âcosts to be controlledâ High performing organizations treat people as valuable strategic assets Three takeaways 1. Give leaders broad authority 2. Encourage them to think like CEO 3. Challenge strong performers ealy with big opportunities Direct support, supervise and help activate the work efforts of others The people who managers help are the ones whose contributions represent the real work of the organisation Types of managers Line managers are responsible for work activities that directly affect organizationâs output Staff managers use technical expertise to advise and support the efforts of line workers Functional managers are responsible for a single area of activity Quality of work life (QWL) An indicator of the overall quality of human experiences in the workplace QWL Indicators Respect Fair pay Safe working conditions Opportunities to learn and use new skills Room to grow and progress in a career Protection of individuals rights The organization as an upside-down pyramid A managerâs job is to support workerâs efforts The best managers are known for helping and supporting Customers at the top served by worker who are supported by managers 1.4 The management Process Managers achieve high performance for their organizations by best utilizing its humans and material resources Management is the process of planning, organizing, leading and controlling the use of resources to accomplish performance goals All managers are responsible for the four functions The functions are carried on continually Characteristics of managerial work Long hours Intense pace Fragmented and varied tasks Many communication media Filled with interpersonal relationships Managerial agendas and networks Agenda setting Develops action priorities for accomplishing goals and plans Networking Process of building and maintaining positive relationships with people who can help advance agendas Social Capital Capacity to attract support and help from others Learning The change in a behaviour that results from experience Lifelong learning The process of continuously learning from daily experiences and opportunities