Section 3 • States of Matter 73

States of Matter

MAIN Idea All matter on Earth and in the universe occurs in the form of a solid, a liquid, a gas, or plasma.

Real-World Reading Link When your skin is wet, even on a hot day, it usu-ally feels cool — especially if it is windy. How can warm air feel cold? When the water evaporates, it absorbs heat from your skin. The harder the wind blows, the more water evaporates and the colder your skin becomes.

SolidsSolids are substances with densely packed particles, which can be ions, atoms, or molecules. Most solids are crystalline structures because the particles of a solid are arranged in regular geometric patterns. Examples of crystals are shown in Figure 3.16. Because of their crys-talline structures, solids have both a definite shape and volume.

Perfectly formed crystals are rare. When many crystals form in the same space at the same time, crowding prevents the formation of perfect crystals with smooth boundaries. The result is a mass of intergrown crystals called a polycrystalline solid. Most solid sub-stances on Earth, including rocks, are polycrystalline solids. Figure 3.16 shows the polycrystalline nature of the rock granite.

Some solid materials have no regular internal patterns. Glass is a solid that consists of densely packed atoms arranged randomly. Glasses form when molten material is chilled so rapidly that atoms do not have enough time to arrange themselves in a regular pattern. These solids do not form crystals, or their crystals are so small that they cannot be seen. Window glass consists mostly of disordered silicon and oxygen ( SiO2).

Objectives

◗ Describe the states of matter on Earth.

◗ Explain the reasons that matter exists in these states.

◗ Relate the role of thermal energy to changes in state of matter.

Review Vocabularychemical reaction: the change of one or more substances into another substance

New Vocabularycrystalline structureglassevaporationplasmacondensationsublimation

■ Figure 3.16 This granite is composed of mineral crystals that fit together like inter-locking puzzle pieces. The minerals that make up the rock are composed of individual atoms and molecules that are aligned in a crystalline structure.

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■ Figure 3.18 The Sun’s temperature is often expressed in kelvins; –273 K is equal to 0°C. The Sun’s corona, which is a plasma, has a temperature of about 15,000,000 K. Compare the temperature of the corona to lightning, which is 30,000 K.

LiquidsAt any temperature above absolute zero (−273°C), the atoms in a solid vibrate. Because these vibrations increase with increasing temperature, they are called thermal vibrations. At the melting point of the material, these vibrations become vigorous enough to break the forces holding the solid together. The particles can then slide past each other, and the substance becomes liquid. Liquids take the shape of the container they are placed in, as you can see in Figure 3.17. However, liquids do have definite volume.

Reading Check Explain the effect that increasing temperature has on the atoms in solids.

GasesThe particles in liquids vibrate vigorously. As a result, some particles can gain sufficient energy to escape the liquid. This process of change from a liquid to a gas at temperatures below the boiling point is called evaporation. When any liquid reaches its boiling point, it vaporizes quickly as a gas.

In gases, the particles are separated by relatively large distances and they travel at high speeds in one direction until they bump into another gas particle or the walls of a container. Gases, like liquids, have no definite shape. Gases also have no definite volume unless they are restrain ed by a container or a force such as gravity. For example, Earth’s gravity keeps gases in the atmosphere from escaping into space.

PlasmaWhen matter is heated to a temperature greater than 5000°C, the collisions between particles are so violent that electrons are knocked away from atoms. Such extremely high temperatures exist in stars and, as a result, the gases of stars consist entirely of positive ions and free electrons. These hot, highly ionized, electrically con-ducting gases are called plasmas. Figure 3.18 shows the plasma that forms the Sun’s corona. You have seen matter in the plasma state if you have ever seen lightning or a neon sign. Both lightning and the matter inside a neon tube are in the plasma state.

74 Chapter 3 • Matter and Change

FOLDABLES

Incorporate information from this section into

your Foldable.

■ Figure 3.17 Each of these contain-ers has the same volume of liquid in it.Explain why the liquids are not all at the same level in the containers.

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Self-Check Quiz glencoe.com Section 3 • States of Matter 75

Section 3.33.3 AssessmentSection Summary◗◗ Changes of state involve thermal

energy.

◗◗ The law of conservation of matter states that matter cannot be created or destroyed.

◗◗ The law of conservation of energy states that energy is neither created nor destroyed.

Understand Main Ideas1. MAIN Idea Explain how thermal energy is involved in changes of state.

2. Evaluate the nature of the thermal vibrations in each of the four states of matter.

3. Apply what you know about thermal energy to compare evaporation and condensation.

Think Critically4. Infer how the boiling point of water (100°C) would change if water molecules

were not polar molecules.

5. Consider glass and diamond—two clear, colorless solids. Why does glass shatter more easily than diamond?

Earth ScienceMATH in6. Refer to Figure 3.18. Calculate the corona’s temperature in degrees. Remember

that 273 K is equal to 0ºC.

■ Figure 3.19 As the hot, moist air from the shower encounters the cool glass of the mirror, the water vapor in the air condenses on the glass. Predict What would happen if the glass were the same temperature as the air?

Changes of StateSolids melt when they absorb enough thermal energy to cause their orderly internal crystalline arrangement to break down. This happens at the melting point. When liquids are cooled, they solid-ify at that same temperature and release thermal energy. The tem-perature at which liquids solidify is called the freezing point.

When a liquid is heated to the boiling point and absorbs enough thermal energy, vaporization occurs and it becomes a gas. When a gas is cooled to the boiling point it becomes a liquid in a process called condensation, shown in Figure 3.19. Energy that was absorbed during vaporization is released upon condensation.

Evaporation can occur below the boiling point when thermal vibrations enable individual atoms or molecules to escape from a solid. You might have noticed that even on winter days with tem-peratures below freezing, snow gradually disappears. This slow change of state from a solid (ice crystals) to a gas (water vapor) without an intermediate liquid state is called sublimation.

Conservation of EnergyThe identity of matter can be changed through chemical reac-tions and nuclear processes, and its state can be changed under different thermal conditions. You have learned that a chemical equation must be balanced because matter cannot be created or destroyed. This fundamental fact is called the law of conservation of matter. Like matter, energy cannot be created or destroyed, but it can be changed from one form to another. For example, electric energy might be converted into light energy. This law, called the conservation of energy, is also known as the first law of thermodynamics.

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Chapter Test glencoe.com Chapter 3 • Assessment 79

Vocabulary Review

Fill in the blank with the correct vocabulary term from the Study Guide.

1. The electrically neutral particles in the nucleus of an atom are called ________.

2. The ________ of an element is equal to the num-ber of ________ in the nucleus of its atoms.

3. Atoms of an element that differ by their mass numbers are called ________.

Explain how both terms in each set below are related.

4. ionic, covalent

5. homogeneous mixture, solution

6. acid, base

Arrange each set of vocabulary terms into a meaningful and true sentence.

7. solid, glass

8. molecules, ions, plasma, gas

9. evaporation, condensation

10. electrons, metallic bond

Understand Key Concepts

Use the figure below to answer Questions 11 to 13.

11. What is the atomic number of this atom?A. 3 C. 5B. 4 D. 6

12. How many valence electrons does this atom have?A. 1 C. 3B. 2 D. 4

13. Which element does this atom represent? (Refer to the periodic table of the elements in Figure 3.2.)A. heliumB. berylliumC. lithiumD. nitrogen

14. What ionic compound is formed by the ions Al3+ and O2‒?A. Al3O2 C. Al2O3B. Al2O D. AlO

Use the figure below to answer Question 15.

15. The figure shows the arrangement of atoms in a substance. What is this substance?A. gasB. glassC. liquidD. solid

16. Which is an example of a heterogeneous mixture?A. coffeeB. soilC. gelatinD. air

17. During the process of sublimation, into what is ice converted?A. hydrogen ions and hydroxide ionsB. hydrogenC. waterD. water vapor

18. Many musical instruments are made of brass, which is a mixture of copper and zinc atoms. What is brass an example of? A solid solutionB. ionic compoundC. chemical reactionD. base

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Chapter Test glencoe.com

19. What happens to the thermal energy of a gas when it condenses and forms a liquid?A. It is released.B. It is absorbed.C. It increases in temperature.D. It decreases in temperature.

20. What kind of ion characterizes an acid?A. oxygen ionB. negative ionC. hydroxide ionD. hydrogen ion

Constructed Response

21. Explain why table salt does not conduct electricity.

22. Explain why gases such as neon and argon do not react with other elements.

23. Illustrate a model atom of potassium (K), indicat-ing the positive charge of the nucleus and the idealized positions of the electrons in the various energy levels. Is potassium a metal or nonmetal? Refer to the periodic table of the elements in Figure 3.2.

Use the figure below to answer Questions 24 and 25.

24. Detect What do these elements have in common?

25. Explain why the atomic masses of these elements are not whole numbers.

26. Distinguish which kind of chemical bond produces a solid that readily conducts heat and electricity.

27. Compare and contrast the physical properties of the elements helium and neon.

Use the figure below to answer Questions 28 and 29.

28. Identify the type of bond shown in the figure. Explain your reasoning.

29. Compare this bond to a metallic bond. Use an illustration to clarify your answer.

30. Deduce what the difference would be between water molecules containing deuterium and those contain-ing ordinary hydrogen atoms. (Hint: Deuterium is an isotope of hydrogen with mass number two. It forms the same chemical compounds as other hydrogen atoms, including water.)

31. Evaluate the statement: Plasma is usually hotter than gas.

Think Critically .

Use the figure below to answer Question 32.

32. Deduce The figure shows an atom of carbon-14. This radioactive isotope decays by converting one of its neutrons to a proton. What element and isotope is produced by the radioactive decay of carbon-14?

80 Chapter 3 • Assessment

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Additional Assessment33. Illustrate Use an illustration to show why water

is effective in dissolving ionic solids such as table salt.

34. Group and list some of the properties that all metals have in common.

35. Assess the correctness of the following statement: Snow that covers the ground can disappear on cold days even when the temperature remains below 0°C.

36. Arrange When hydrochloric acid (HCl) is added to the sedimentary rock limestone (CaCO3), car-bon dioxide (CO2), calcium chloride (CaCl2) and water (H2O) are given off. Arrange the chemical compounds listed above into a balanced equation that shows this chemical reaction.

37. Hypothesize Earth’s upper atmosphere—the ionosphere — conducts electricity. Hypothesize about the state of matter in the ionosphere.

38. Careers in Earth Science Assess the importance of understanding chemical reactions in order to interpret the conditions of rocks and minerals that are present on other planets.

39. Estimate Air at sea level has a density of 0.13 g/L. Estimate how much air, in kilograms, fills your classroom. (Hint: to start, multiply the length, width, and height of your classroom to calculate the room’s volume.)

Concept Mapping

40. Create a concept map using the following terms or phrases: ionic bond, covalent bond, metallic bond, shared electrons, gain or lose electrons, a sea of electrons, molecule, and compound.

Challenge Question

41. An atom is mostly empty space. A typical atom has a diameter of 10‒10 m with a nucleus of diam-eter 10‒14 m. To visualize this, enlarge this atom by a factor of 108 (100 million) so that its nucleus has the size of a marble (1 cm). What would be the diameter of this enlarged atom? Would this atom fit into a football field?

Chapter 3 • Assessment 81Chapter Test glencoe.com

42. Earth Science Prepare a news release reporting on the discovery of a new chemical element. The element has 121 protons in its nucleus. Be sure to include the characteristics of this element and its location in the periodic table.

Document–Based QuestionsData obtained from: Mineral resource of the month: magnesium. Geotimes: 50, no. 11 (November 2005): 57.

Magnesium is lightweight and has a high strength-to-weight ratio. It constitutes about 2 percent of the crust and its concentration in seawater is 0.13 per-cent. Magnesium is present in more than 60 minerals and is produced from magnesium-bearing ores, sea-water, and brines.

Magnesium is made into an alloy with aluminum to increase strength and corrosion resistance, especially in beverage cans. Its light weight makes it useful in aircrafts, cars, chain saws, lawn mowers, and other machine parts. Annual world magnesium production is 584,000 metric tons. China produces the most at 426,000 metric tons. Yearly production in the United States, is 43,000 metric tons and U.S. consumption is 140,000 metric tons per year. Canada, China, Israel, and Russia supply 92 percent of U.S. magnesium imports. Recycling covers about 15 percent of U.S. magnesium consumption.

43. Determine the amount of magnesium in 1 m3 of seawater. Express your answer in kilograms.

44. Analyze and explain the role of magnesium in the manufacture of cars and beverage cans.

45. Compare and contrast the production of magne-sium in the United States and other countries. How does U.S. dependence on imports affect these other countries?

Cumulative Review

46. Why is the concept of time and scale in the study of Earth science difficult to understand? (Chapter 1)

47. In the collection of data, measurements must follow what general guidelines? (Chapter 1)

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