FORCE, Bending, Twisting,Squeezing, Stretching, Pushing, pulling

Cohesion and Adhesion Water molecules stick to each other as a result of hydrogen bond- ing. An attractive force that holds molecules of a single substance together is known as cohesion. Cohesion due to hydrogen bonding between water molecules contributes to the upward movement of water from plant roots to their leaves. Related to cohesion is the surface tension of water. The cohe- sive forces in water resulting from hydrogen bonds cause the mol- ecules at the surface of water to be pulled downward into the liquid. As a result, water acts as if it has a thin “skin” on its sur- face. You can observe water’s surface tension by slightly overfill- ing a drinking glass with water. The water will appear to bulge above the rim of the glass. Surface tension also enables small crea- tures such as spiders and water-striders to run on water without breaking the surface. Adhesion is the attractive force between two particles of differ- ent substances, such as water molecules and glass molecules. A related property is capillarity (KAP-uh-LER-i-tee), which is the attrac- tion between molecules that results in the rise of the surface of a liquid when in contact with a solid. Together, the forces of adhe- sion, cohesion, and capillarity help water rise through narrow tubes against the force of gravity. Figure 2-11 shows cohesion and adhesion in the water-conducting tubes in the stem of a flower. Temperature Moderation Water has a high heat capacity, which means that water can absorb or release relatively large amounts of energy in the form of heat with only a slight change in temperature. This property of water is related to hydrogen bonding. Energy must be absorbed to break hydrogen bonds, and energy is released as heat when hydrogen bonds form. The energy that water initially absorbs breaks hydro- gen bonds between molecules. Only after these hydrogen bonds are broken does the energy begin to increase the motion of the water molecules, which raises the temperature of the water. When the temperature of water drops, hydrogen bonds reform, which releases a large amount of energy in the form of heat. Therefore, during a hot summer day, water can absorb a large quantity of energy from the sun and can cool the air without a large increase in the water’s temperature. At night, the gradually cooling water warms the air. In this way, the Earth’s oceans stabilize global temperatures enough to allow life to exist. Water’s high heat capac- ity also allows organisms to keep cells at an even temperature despite temperature changes in the environment. As a liquid evaporates, the surface of the liquid that remains behind cools down. A relatively large amount of energy is absorbed by water during evaporation, which significantly cools the surface of the remaining liquid. Evaporative cooling prevents organisms that live on land from overheating. For example, the evaporation of sweat from a person’s skin releases body heat and prevents over- heating on a hot day or during strenuous activity. Adhesion Cohesion Hydrogen bonds Cohesion, adhesion, and capillarity contribute to the upward movement of water from the roots of plants. FIGURE 2–11 www.scilinks.org Topic: Hydrogen Bonding Keyword: HM60777 mb06se_cols03.qxd 5/18/07 10:47 AM Page 41 42 CHAPTER 2 Density of Ice Unlike most solids, which are denser than their liquids, solid water is less dense than liquid water. This property is due to the shape of the water molecule and hydrogen bonding. The angle between the hydrogen atoms is quite wide. So, when water forms solid ice, the angles in the molecules cause ice crystals to have large amounts of open space, as shown in Figure 2-12. This open space lattice structure causes ice to have a low density. Because ice floats on water, bodies of water such as ponds and lakes freeze from the top down and not the bottom up. Ice insulates the water below from the cold air, which allows fish and other aquatic crea- tures to survive under the icy surface.

Religions Buddhism, Islam, and Christianity are all practiced within Southeast Asia. Buddhism, particularly the more orthodox Theravada form, dominates the religious pattern of most of the mainland; only in northern Vietnam is the more liberal Mahayana Buddhism more common. Islam is predominant in the southern half of the Malay Peninsula, the Malay Archipelago, and the southern Philippines. As a result of the large Muslim population in Indonesia, Islam is the religion of some two-fifths of Southeast Asians. The diffusion of the religion began in the early 14th century through contact with Muslim traders in northern Sumatra. Perhaps more than any of the other religions, Islam has been a strong force in binding together its adherents. It has profoundly affected cultural, social, political, and economic matters in areas where it is practiced. The spread of Christianity came with European contact. Roman Catholicism was introduced to insular Southeast Asia by the Spanish and the Portuguese in the 16th century and somewhat later to the Indochinese Peninsula by the French. Catholicism is most important in the Philippines and southern Vietnam. Protestantism also is locally important. The Batak and Minangkabau peoples in Sumatra and a growing number of Chinese in Singapore and elsewhere adhere to various Protestant denominations. Hinduism, once much more widespread, now is practiced by many people in the region’s Indian communities. In addition, this religion, modified by animism and other influences, is the primary faith on the island of Bali in Indonesia. Various forms of animism also are practiced in the region’s more remote areas, particularly in central Borneo, northern Laos, and northern Myanmar.

Many of water’s biological functions stem from its chemical struc- ture. Recall that in the water molecule, H2O, the hydrogen and oxygen atoms share electrons to form covalent bonds. However, these atoms do not share the electrons equally. The oxygen atom has a greater ability to attract electrons to it because it pulls hydrogen’s electrons towards its nucleus. As a result, as shown in Figure 2-8, the region of the molecule where the oxygen atom is located has a partial negative charge, denoted with a , while the regions of the molecule where each of the two hydrogen atoms are located have partial positive charges, each of which are denoted with a . Thus, even though the total charge on a water molecule is neutral, the charge is unevenly distributed across the water molecule. Because of this uneven distribution of charge, water is called a polar compound. Notice also in Figure 2-8 that the three atoms in a water mole- cule are not arranged in a straight line as you might expect. Rather, the two hydrogen atoms bond with the single oxygen atom at an angle. SECTION 3 OBJECTIVES ● Describe the structure of a water molecule. ● Explain how water’s polar nature affects its ability to dissolve substances. ● Outline the relationship between hydrogen bonding and the different properties of water. ● Identify the roles of solutes and solvents in solutions. ● Differentiate between acids and bases. VOCABULARY polar hydrogen bond cohesion adhesion capillarity solution solute solvent concentration saturated solution aqueous solution hydroxide ion hydronium ion acid base pH scale buffer Copyright © by Holt, Rinehart and Winston. All rights reserved. (a) Electron cloud model (b) Space-filling model H H O The oxygen region of the water molecule is weakly negative, and the hydrogen regions are weakly positive. Notice the different ways to represent water, H2O. You are familiar with the electron cloud model (a). The space- filling model (b) shows the three- dimensional structure of a molecule. FIGURE 2-8 40 CHAPTER 2 Hydrogen bond H H H H H H H H H O O O O O O H H H H H – – – – – – – + + + + + + + + + + + + + + The dotted lines in this figure represent hydrogen bonds. A hydrogen bond is a force of attraction between a hydrogen atom in one molecule and a negatively charged region or atom in a second molecule. FIGURE 2-10 The positive region of a water molecule attracts the negative region of an ionic compound, such as the Cl portion of NaCl. Similarly, the negative region of the water molecule attracts the positive region of the compound—the Na portion of NaCl. As a result, NaCl breaks apart, or dissolves, in water. FIGURE 2-9 CI– Na+ H2O + + – – Solubility of Water The polar nature of water allows it to dissolve polar substances, such as sugars, ionic compounds, and some proteins. Water does not dissolve nonpolar substances, such as oil because a weaker attraction exists between polar and nonpolar molecules than between two polar molecules. Figure 2-9 shows how water dissolves the ionic compound sodium chloride, NaCl. In your body, ions, such as sodium and chloride, are essential to bodily func- tions, such as muscle contraction and transmission of impulses in the nervous system. In fact, dissolved, or dissociated ions, are pre- sent in all of the aqueous solutions found in living things and are important in maintaining normal body functions. HYDROGEN BONDING The polar nature of water also causes water molecules to be attracted to one another. As is shown in Figure 2-10, the positively charged region of one water molecule is attracted to the negatively charged region of another water molecule. This attraction is called a hydrogen bond. A hydrogen bond is the force of attraction between a hydrogen molecule with a partial positive charge and another atom or molecule with a partial or full negative charge. Hydrogen bonds in water exert an attractive force strong enough so that water “clings” to itself and some other substances. Hydrogen bonds form, break, and reform with great frequency. However, at any one time, a great number of water molecules are bonded together. The number of hydrogen bonds that exist depends on the state that water is in. If water is in its solid state all its water molecules are hydrogen bonded and do not break. As water liquifies, more hydrogen bonds are broken than are formed, until an equal number of bonds are formed and broken. Hydrogen bonding accounts for the unique properties of water, some of which we will examine further. These properties include cohesion and adhesion, the ability of water to absorb a relatively large amount of energy as heat, the ability of water to cool surfaces through evaporation, the density of ice, and the ability of water to dissolve many substances.

Unit 5 B Bonding Molecular Forces Practice Test

When it was his turn to speak, Adam Malik, Presidium Minister for Political Affairs and Minister for Foreign Affairs of Indonesia, recalled that about a year before, in Bangkok, at the conclusion of the peace talks between Indonesia and Malaysia, he had explored the idea of an organization such as ASEAN with his Malaysian and Thai counterparts. One of the “angry young men” in his country’s struggle for independence two decades earlier, Adam Malik was then 50 years old and one of a Presidium of five led by then General Soeharto that was steering Indonesia from the verge of economic and political chaos. He was the Presidium’s point man in Indonesia’s efforts to mend fences with its neighbors in the wake of an unfortunate policy of confrontation. During the past year, he said, the Ministers had all worked together toward the realization of the ASEAN idea, “making haste slowly, in order to build a new association for regional cooperation.” Adam Malik went on to describe Indonesia’s vision of a Southeast Asia developing into “a region which can stand on its own feet, strong enough to defend itself against any negative influence from outside the region.” Such a vision, he stressed, was not wishful thinking, if the countries of the region effectively cooperated with each other, considering their combined natural resources and manpower. He referred to differences of outlook among the member countries, but those differences, he said, would be overcome through a maximum of goodwill and understanding, faith and realism. Hard work, patience and perseverance, he added, would also be necessary. The countries of Southeast Asia should also be willing to take responsibility for whatever happens to them, according to Tun Abdul Razak, the Deputy Prime Minister of Malaysia, who spoke next. In his speech, he conjured a vision of an ASEAN that would include all the countries of Southeast Asia. Tun Abdul Razak was then concurrently his country’s Minister of Defence and Minister of National Development. It was a time when national survival was the overriding thrust of Malaysia’s relations with other nations and so as Minister of Defence, he was in charge of his country’s foreign affairs. He stressed that the countries of the region should recognize that unless they assumed their common responsibility to shape their own destiny and to prevent external intervention and interference, Southeast Asia would remain fraught with danger and tension. And unless they took decisive and collective action to prevent the eruption of intra-regional conflicts, the nations of Southeast Asia would remain susceptible to manipulation, one against another. “We the nations and peoples of Southeast Asia,” Tun Abdul Razak said, “must get together and form by ourselves a new perspective and a new framework for our region. It is important that individually and jointly we should create a deep awareness that we cannot survive for long as independent but isolated peoples unless we also think and act together and unless we prove by deeds that we belong to a family of Southeast Asian nations bound together by ties of friendship and goodwill and imbued with our own ideals and aspirations and determined to shape our own destiny”. He added that, “with the establishment of ASEAN, we have taken a firm and a bold step on that road”. For his part, S. Rajaratnam, a former Minister of Culture of multi-cultural Singapore who, at that time, served as its first Foreign Minister, noted that two decades of nationalist fervor had not fulfilled the expectations of the people of Southeast Asia for better living standards. If ASEAN would succeed, he said, then its members would have to marry national thinking with regional thinking. “We must now think at two levels,” Rajaratnam said. “We must think not only of our national interests but posit them against regional interests: that is a new way of thinking about our problems. And these are two different things and sometimes they can conflict. Secondly, we must also accept the fact, if we are really serious about it, that regional existence means painful adjustments to those practices and thinking in our respective countries. We must make these painful and difficult adjustments. If we are not going to do that, then regionalism remains a utopia.” S. Rajaratnam expressed the fear, however, that ASEAN would be misunderstood. “We are not against anything”, he said, “not against anybody”. And here he used a term that would have an ominous ring even today: balkanization. In Southeast Asia, as in Europe and any part of the world, he said, outside powers had a vested interest in the balkanization of the region. “We want to ensure,” he said, “a stable Southeast Asia, not a balkanized Southeast Asia. And those countries who are interested, genuinely interested, in the stability of Southeast Asia, the prosperity of Southeast Asia, and better economic and social conditions, will welcome small countries getting together to pool their collective resources and their collective wisdom to contribute to the peace of the world.” The goal of ASEAN, then, is to create, not to destroy. This, the Foreign Minister of Thailand, Thanat Khoman, stressed when it was his turn to speak. At a time when the Vietnam conflict was raging and American forces seemed forever entrenched in Indochina, he had foreseen their eventual withdrawal from the area and had accordingly applied himself to adjusting Thailand’s foreign policy to a reality that would only become apparent more than half a decade later. He must have had that in mind when, on that occasion, he said that the countries of Southeast Asia had no choice but to adjust to the exigencies of the time, to move toward closer cooperation and even integration. Elaborating on ASEAN objectives, he spoke of “building a new society that will be responsive to the needs of our time and efficiently equipped to bring about, for the enjoyment and the material as well as spiritual advancement of our peoples, conditions of stability and progress. Particularly what millions of men and women in our part of the world want is to erase the old and obsolete concept of domination and subjection of the past and replace it with the new spirit of give and take, of equality and partnership. More than anything else, they want to be master of their own house and to enjoy the inherent right to decide their own destiny …” While the nations of Southeast Asia prevent attempts to deprive them of their freedom and sovereignty, he said, they must first free themselves from the material impediments of ignorance, disease and hunger. Each of these nations cannot accomplish that alone, but by joining together and cooperating with those who have the same aspirations, these objectives become easier to attain. Then Thanat Khoman concluded: “What we have decided today is only a small beginning of what we hope will be a long and continuous sequence of accomplishments of which we ourselves, those who will join us later and the generations to come, can be proud. Let it be for Southeast Asia, a potentially rich region, rich in history, in spiritual as well as material resources and indeed for the whole ancient continent of Asia, the light of happiness and well-being that will shine over the uncounted millions of our struggling peoples.” The Foreign Minister of Thailand closed the inaugural session of the Association of Southeast Asian Nations by presenting each of his colleagues with a memento. Inscribed on the memento presented to the Foreign Minister of Indonesia, was the citation, “In recognition of services rendered by His Excellency Adam Malik to the ASEAN organization, the name of which was suggested by him.” And that was how ASEAN was conceived, given a name, and born. It had been barely 14 months since Thanat Khoman brought up the ASEAN idea in his conversations with his Malaysian and Indonesian colleagues. In about three more weeks, Indonesia would fully restore diplomatic relations with Malaysia, and soon after that with Singapore. That was by no means the end to intra-ASEAN disputes, for soon the Philippines and Malaysia would have a falling out on the issue of sovereignty over Sabah. Many disputes between ASEAN countries persist to this day. But all Member Countries are deeply committed to resolving their differences through peaceful means and in the spirit of mutual accommodation. Every dispute would have its proper season but it would not be allowed to get in the way of the task at hand. And at that time, the essential task was to lay the framework of regional dialogue and cooperation. The two-page Bangkok Declaration not only contains the rationale for the establishment of ASEAN and its specific objectives. It represents the organization’s modus operandi of building on small steps, voluntary, and informal arrangements towards more binding and institutionalized agreements. All the founding member states and the newer members have stood fast to the spirit of the Bangkok Declaration. Over the years, ASEAN has progressively entered into several formal and legally-binding instruments, such as the 1976 Treaty of Amity and Cooperation in Southeast Asia and the 1995 Treaty on the Southeast Asia Nuclear Weapon-Free Zone. Against the backdrop of conflict in the then Indochina, the Founding Fathers had the foresight of building a community of and for all Southeast Asian states. Thus the Bangkok Declaration promulgated that “the Association is open for participation to all States in the Southeast Asian region subscribing to the aforementioned aims, principles and purposes.” ASEAN’s inclusive outlook has paved the way for community-building not only in Southeast Asia, but also in the broader Asia Pacific region where several other inter-governmental organizations now co-exist. The original ASEAN logo presented five brown sheaves of rice stalks, one for each founding member. Beneath the sheaves is the legend “ASEAN” in blue. These are set on a field of yellow encircled by a blue border. Brown stands for strength and stability, yellow for prosperity and blue for the spirit of cordiality in which ASEAN affairs are conducted. When ASEAN celebrated its 30th Anniversary in 1997, the sheaves on the logo had increased to ten – representing all ten countries of Southeast Asia and reflecting the colors of the flags of all of them. In a very real sense, ASEAN and Southeast Asia would then be one and the same, just as the Founding Fathers had envisioned. This article is based on the first chapter of ASEAN at 30, a publication of the Association of Southeast Asian Nations in commemoration of its 30th Anniversary on 8 August 1997, written by Jamil Maidan Flores and Jun Abad.

force

110.31.b.17.C

Topic: Reading/Vocabulary Development

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