Writing Acid Formulas

Covalent 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 (“two atoms”) molecules H2, N2, O2, F2, Cl2, Br2, and I2 (part (a) in Figure 3.1.1). Similarly, a few pure elements exist as polyatomic (“many atoms”) 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 13–15, 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 “laughing gas,” 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 “unpressurized” 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 O2−. 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 NO3− ions combine in a 1:1 ratio to form KNO3 (potassium nitrate or saltpeter), a major ingredient in black gunpowder. Similarly, Ca2+ and SO42− form CaSO4 (calcium sulfate), which combines with varying amounts of water to form gypsum and plaster of Paris. The polyatomic ions NH4+ and NO3− 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 PO43− 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(−3) = −6], 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 PO43− 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.

Unit 9 Acid Naming and Formula Writing

Name: Marco Ramirez - “I Am Not Batman” TW: language It’s the middle of the night. And the sky is glowing like mad radioactive red. And if you squint, you could maybe see the moon through a thick layer of cigarette smoke and airplane exhaust that covers the entire city like mosquito net that won’t let the angels in. And if you look up high enough you could see me-standing on the edge of a eighty seven story building. And up there-a place for gargoyles and broken clock towers that have stayed still and dead for maybe like a hundred years-up there is me. And I’m freakin Batman. And I gots Bat-mobiles and Bat-a-rangs and freakin Bat-caves like for real, and all it takes is a broom closet or a back room or a fire escape and Danny’s hand-me-down jeans are gone. And my navy blue polo shirt? – The one that looks kinda good on me but has a hole on it near the butt from when it got snagged on the chain linked fence behind Arturo’s but it isn’t even a big deal cause I tuck that part in and its like all good? –that blue polo shirt? – It’s gone too. And I get like, like transformational. And nobody pulls out a belt and whips Batman for talking back –-Or for not talking back –And nobody calls Batman simple –- Or stupid –- Or skinny –- And nobody fires Batman’s brother from the Eastern Taxi Company ‘cause they was making cutbacks, neither, ‘cause they got nothing but respect, and not like afraid-respect. Just like respect-respect. ‘Cause nobody’s afraid of you. Cause Batman doesn’t mean nobody harm. Ever. Cause all Batman really wants to do is save people and maybe pay Abuela’s bills one day and die happy and maybe get like mad famous. For real.…And kill the Joker. Tonight, like most nights, I’m all alone. And I’m watching…And I’m waiting… Like a eagle. Or like a –no, yea, like a eagle. And my cape is flappin’ in the wind (‘cause it’s freakin’ long), and my pointy ears are on, and that mask that covers like half my face is on too, and I got like bulletproof stuff all in my chest so no one could hurt me and nobody – nobody – is gonna come between Batman, And Justice. From where I am I could hear everything. Somewhere in the city there’s a old lady picking Styrofoam leftovers up outta a trash can and she’s putting a piece of sesame chicken someone spit out into her own mouth. And somewhere there’s a doctor with a whack haircut in a black lab coat trying to find a cure for the diseases that are gonna make us all extinct for real one day. And somewhere there’s a man, a man in a janitor’s uniform, stumbling home drunk and dizzy after spending half his paycheck on forty-ounce bottles of twist-off beer and the other half on a four hour visit to some lady’s house on a street where the lights have all been shot out by people who’d rather do what they do, in this city, in the dark. And half a block away from JanitorMan there’s a group of good-for-nothings who don’t know no better waiting to beat JanitorMan with rusted bicycle chains and imitation Lousiville Sluggers, and if they don’t find a cent on him – which they won’t – they’ll just pound at him till the muscles in their arms start burning, till there’s no more teeth to crack out. But they don’t count on me. They don’t count on no dark night (with a stomach full of grocery store brand macaroni-and-cheese and cut up Vienna sausages), Cause they’d rather believe I don’t exist, And from eighty-seven stories up I could hear one of the good-for-nothings say “Gimmethecash” real fast (like that) just “Gimmethefuckingcash” and I see JAnitorMan mumble something in drunk language and turn pale and from eighty-seven stories up I could hear his stomach trying to hurl its way out of his Dickies. So I swoop down like and fast and I’m like darkness. I’m like SWOOSH –- And I throw a Bat-a-rang at the one naked lightbulb –- And they’re all like “whoa-motherfucker-who-just-turned-out-the-lights?” –“What’s that over there?” –-“What?” –- “Gimme whatchou got old man” –- “Did anybody hear that?!” –- “No, really” –- “There ain’t. No. Bat.” – But then –- One out of three good-for-nothings gets it to the head! And number Two swings blindly into the dark cape before him but before his fist hits anything I grab a trash can lid and –-- Right into the gut, and number One comes back with a jump-kick but I know judo-karate too so I’m like –-- Twice –-- but before I can do any more damage suddenly we all hear a CLIC – CLIC –And suddenly everything gets quiet And the one good-for-nothing left standing grips a handgun and aims straight up, like he’s holding Jesus hostage, like he’s threatening maybe to blow a hole in the moon. And the good-for-nothing who got it to the head who tried to jump-kick me and the other good-for-nothing who got it in the gut is both scrambling back away from the dark figure before him. And the drunk man the JanitorMan is huddled in a corner, praying to Saint Anthony ‘cause that’s the only one he could remember. And there’s me, Eyes glowing white, cape blowing softly in the wind. Bulletporoof chest heaving. My heart beating right through it in a Morse code for “fuck with me, just once, come on, just try.” And the one good-for-nothing left standing, the one with the handgun, he laughs he lowers his arm, and he points it at me and gives the moon a break, and he aims it right between my pointy ears, like goalposts and he’s special teams. And JanitorMan is still calling Saint Anthony but he ain’t pickin’ up, And for a second it seems like…maybe I’m gonna lose. Naw. SHOO – SHOO! FUACATA! --“Don’t kill me man!” –“SNAP! – Wrist CRACK – Neck – SLASH! – Skin – meets – acid – “AHH!!” –And he’s on the floor. And I’m standing over him. And I got the gun in MY hands now. And I hate guns, I hate holding ‘em cause I’m Batman, and –Batman don’t like guns ‘cause his parents got iced by guns a long time ago – but for just a second, my eyes glow white, and I hold this thing, for I could speak to the good-for-nothing in a language he maybe understands…CLIC – CLIC…And the good-for-nothings become good-for-disappearing into whatever toxic-waste-chemical-sludge-shit-hole they crawled out of. And it’s just me and JanitorMan. And I pick him up. And I wipe sweat and cheap perfume off his forehead. And he begs me not to hurt him and I grab him tight by his JanitorMan shirt collar and I pull him to my face, and he’s taller than me, but the cape helps so he listens when I look him straight in the eyes and I say two words to him: “Go home.” And he does, checking behind his shoulder every ten feet. And I SWOOSH from building to building on his way there, ‘cause I know where he lives. And I watch his hands where he lives. And I watch his hands tremble as he pulls out his keychain and opens the door to his building. And I’m back in bed before he even walks in through the front door. And I hear him turn on the faucet and pour himself a glass of warm tap water And he puts the glass back in the sink. And I hear his footsteps, And they get slower as they get to my room. And he creaks my door open like mad slow. And he takes a step in, which he never does. And he’s staring off into nowhere, his face the color of sidewalks in summer, and I act like I’m just waking up, and I say, “What’s up, Pop?” And JanitorMan says nothing to me. But I see, in the dark, I see his arms go limp and his head turns back, like towards me, and he lifts it for I could see his face, For I could see his eyes, And his cheeks is dripping but not with sweat. And he just stands there, breathing, like he remembers my eyes glowing white. Like he remembers my bulletproof chest. Like he remembers he’s my pop. And for a long time I don’t say nothing. And he turns around, hand on the doorknob, and he ain’t looking up my way but I hear him mumble two words to me. “I’m sorry.” And I lean over and open my window just a crack.… If you look up high enough you could see me. And from where I am? I could hear everything.

Writing

110.31.b.17.C

Topic: Reading/Vocabulary Development

STAAR English II High School 2014 - Past Paper

110.31.b.1.B

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