Minerals

1. Chapter 2 Minerals

2. Matter Every object in the universe is made of particles of some kind of substance. Scientists use the word matter to describe the substance of which an object is made. Matter is anything that takes up space and has a mass. The amount of matter in an object determines the mass of that object.

3. Matter There are several ways to classify matter. One way is to classify it into three physical forms – solid, liquid, and gas. The particles that make up a solid are packed tightly together in fixed positions and are not free to move very much. Therefore, a solid has a definite shape and a definite volume.

4. Matter In a liquid, the particles are also tightly packed together, but they are free to move. So a liquid has a definite volume, but it does not have a definite shape. Gas particles are farther apart and move faster and more freely than those of a liquid. So a gas has no definite volume or shape.

5. Matter Scientists are able to identify the kind of matter that makes up a substance by observing the properties of that substance. All matter has two types of distinguishing properties. Physical properties are those characteristics that can be observed without changing the composition of the substance. Ex: Density, color, hardness, freezing point, boiling point, ability to conduct electricity, etc.

6. Matter Chemical properties are those characteristics that describe how a substance interacts with other substances to produce different kinds of matter. Ex: A chemical property of iron is that it interacts with oxygen to form iron oxide (rust). A chemical property of helium is that it usually does not interact with other substances. Understanding the chemical properties of a substance requires some basic information about the particles that make up all substances.

7. Matter All matter is made up of elements. An element is a substance that has a characteristic set of physical and chemical properties.

8. Matter Notice that there is a universally understood symbol of one or two letters that represents each element. Over 90 elements occur naturally in the earth. Another dozen or so have been created in the laboratory. Of the natural elements, only 8 make up over 98% of the earth’s crust. Silicon and Oxygen make up almost 75% of the earth’s crust.

9. Matter

10. Which of the following is not one of the eight most common elements in Earth’s continental crust? Carbon Silicon Oxygen Aluminum

11. The most abundant element in Earth’s continental crust (by weight) is Oxygen Silicon Calcium Iron

12. What are the building blocks of minerals? Rocks Elements Isotopes Electrons

13. Matter Elements consist of atoms. An atom is the smallest unit of an element and has all the properties of that element. The word atom comes from a Greek word (atomos) for “indivisible.” You can identify an element by its atoms. The atoms of any one element are significantly different from the atoms of any other element.

14. Matter Atoms cannot be broken down into smaller particles that have the same chemical and physical properties by ordinary physical or chemical processes. An atom is so small that the size of a single atom is difficult to imagine. Ex: To get an idea of how small an atom is, look at the thickness of a piece of paper. More than a million atoms lined up side by side would equal that thickness.

15. Matter As tiny as atoms are, they are made up of even smaller parts called subatomic particles. The three major kinds of subatomic particles are electrons, protons, and neutrons. Electrons carry a negative electrical charge, protons carry a positive electrical charge, and neutrons are neutral (no electrical charge).

16. Matter Subatomic particles are arranged in a similar way within all small atoms. The protons and neutrons of an atom are packed close to one another in the nucleus. A small region in the center of the atom. Because the neutrons carry no charge, the protons give a nucleus a positive charge. Compared to the size of the whole atom, the nucleus takes up about the same space as a gumball in a football stadium.

17. The central region of an atom is called the Proton. Electron. Nucleus. Neutron.

18. The smallest particle of an element that still retains the element’s properties is an Compound. Atom. Isotope. Mineral.

19. Matter The electrons of an atom move in a certain region of space around the nucleus known as an energy levels. Each energy level contains a certain number of electrons. Electrons are about 1/1836 the mass of a proton or neutron. Because unlike electrical charges attract, the negatively charged electrons are attracted to the positively charged nucleus. The electrons tend to remain relatively close to the nucleus of an atom, but the constant motion of the electrons keeps them from falling into the nucleus.

20. Matter

21. Matter An atom of a specific element is distinguished from the atoms of all other kinds of elements by the number of its protons. To help in the identification of elements, scientists have assigned an atomic number to each kind of atom. The atomic number is equal to the number of protons in the nucleus. All atoms of any one element have the same atomic number.

22. Matter An uncharged atom has equal numbers of protons and electrons. Thus, the atomic number also equals the number of electrons in an uncharged atom of that element. Atomic number is one of the components listed for each element in the periodic table. The periodic table is a system for classifying elements. Elements in the same column on the periodic table have similar arrangements of their electrons and have similar chemical behavior.

23. Matter Each atom also has a mass number. The mass number of any atom represents the sum of the number of protons and neutrons in that atom. The actual mass of a subatomic particle is so small that, rather than grams, a special unit called atomic mass unit (amu) is used. Protons and neutrons each have an atomic mass close to 1 amu. Electrons are much less massive, in fact, it takes the combined mass of about 1,836 electrons to equal the mass of 1 proton.

24. Matter Although all atoms of a given element contain the same number of protons, they do not always contain the same number of neutrons. Because the mass number is equal to the sum of the protons and neutrons in the nucleus, each additional neutron increases the mass number. Atoms of the same element that differ from each other in mass number are called isotopes. Ex: Hydrogen has 3 isotopes.

25. If the atomic number of an element is 6 and its mass number is 14, how many neutrons are contained in the nucleus? 6 20 14 8

26. Atoms containing the same numbers of protons and different numbers of neutrons are Isotopes. Ions. Neutrons. Compounds.

27. Isotopes of the same element differ in the number of Protons. Electrons. Neutrons. Nuclei.

28. The mass number of an atom is obtained by totaling the number of Electrons and Protons. Electrons and Neutrons. Protons and Neutrons. Neutrons and Isotopes.

29. Matter Elements rarely occur in pure form in the earth’s crust. Instead they are generally found in combination with other elements. When the atoms of two or more elements are chemically united, the resulting substance is called a compound. A compound is a new substance with properties different from those of the elements that compose it.

30. When two or more elements bond together in definite proportions, they form a Ion. Atom. Nucleus. Compound.

31. Matter The smallest complete unit of a compound is called a molecule. Ex: Water (H2O) Some elements exist naturally as diatomic molecules, molecules made up of two atoms. Ex: Hydrogen (H2) and Oxygen (O2).

32. Matter Different kinds of atoms join together and form compounds based upon the way their electrons are arranged. Within the electron cloud of an atom, electrons are arranged in energy levels. The electrons in each energy level have a specific amount of energy, and each energy level can hold only a certain maximum number of electrons. Ex: The first energy level can only hold 2 electrons. The second energy level can hold up to 8 electrons.

33. Which subatomic particles are most involved in chemical bonding? Protons Electrons. Neutrons. Isotopes.

34. What is the smallest particle of a covalent compound that shows the properties of that compound? An ion. An atom. An element. A molecule.

35. Matter

36. Matter An electron occupies only one energy level at a time, although it may go to higher or lower levels. Also, an atom can contain several different levels of electrons. Electrons fill the lower, or inner, level first, then the upper, or outer, levels. Think of energy levels as the rungs on a ladder. In order to get to the top of the ladder, you must start on the lowest rung and work your way up.

37. Matter No matter how many energy levels are occupied in an atom, the outermost level can never hold more than eight electrons. Not all atoms have the maximum number of electrons in their outermost energy level. The most stable atoms are those in which the outermost energy level is filled. Atoms with filled outer energy levels do not easily lose or gain electrons, so they do not easily form compounds with other elements (Noble Gases).

38. Matter Atoms of certain elements give up electrons more easily than atom of certain other elements. Atoms with one, two, or three electrons in the outermost level give up electrons easily. The elements that have these limited number of electrons in the outermost level are the same elements that have metallic properties and are classified as metals.

39. Matter Metals have a number of useful characteristics. Most metals are good conductors of heat and electricity. Many are malleable, which means they can be hammered into thin sheets. These metals are also ductile, which means they can be drawn out into wire.

40. Matter Atoms with four or more electrons in the outermost level are less likely to lose electrons easily. These are elements with less-metallic properties and are generally classified as nonmetals. Ex: Carbon (C), Nitrogen (N), Oxygen (O), etc.

41. Matter The atoms that combine to make up a compound are held together by forces called chemical bonds. A chemical bond is produced by the interaction of electrons from the outermost energy levels of two or more atoms. Atoms can form chemical bonds by sharing electrons or by transferring electrons from one atom to another. In both cases, the attraction that joins the atoms is the pull of an electrical charge.

42. Matter When electrons are transferred from one atom to another, the bond is an ionic bond. A compound formed through the transfer of electrons is called an ionic compound. Most ionic compounds are formed by the transfer of electrons from a metal to a nonmetal. Ex: Sodium Chloride (NaCl) = Table Salt.

43. Matter

44. Matter When an electron is transferred from one atom to another, both atoms become electrically charged. An ion is an atom or group of atoms that carries an electrical charge.

45. An atom that loses or gains electrons is called a Isotope. Proton. Neutron. Ion.

46. Matter A bond based on the attraction between atoms that share electrons is a covalent bond. Water is an example of a covalent compound – that is, a compound formed by the sharing of electrons. Each covalent compound consists of only one kind of molecule, just as each element consists of only one kind of atom.

47. Matter When atoms share electrons, the positive nucleus of each atom is attracted to the negative electrons being shared. The pull between the positive and negative charges is the force that keeps the atoms joined. In diatomic gases such as Nitrogen (N2) and Oxygen (O2), there are covalent bonds between the two atoms of each diatomic molecule.

48. Matter In a covalent compound, the electrons are shared, but the nucleus of one atom pulls more strongly than the other. The electrons are shared but remain closer to the nucleus that pulls more strongly.

49. Matter Each molecule that makes up a covalent compound is usually held to other molecules by weak forces of attraction. These forces are far weaker than the powerful attraction between ions in an ionic compound. For this reason, a covalent compound melts at a much lower temperature than does an ionic compound.

50. Matter Metallic bonds form when electrons are shared by metal ions. The sharing of an electron gives metals their characteristic properties.

51. Which of the following statements about the chemical combination of atoms to form compounds is not true? Compounds form when atoms are more stable in a combined form. When atoms combine, they gain, lose, or share electrons. When atoms combine, they are at a lower energy state. Compounds form when atoms are less stable in a combined form.

52. The main types of chemical bonds are Ionic, covalent, and metallic. Ionic, compound, and metallic. Isotopic, covalent, and metallic. Ionic, covalent, and nonmetallic.

53. What type of chemical bond forms between positive and negative ions? Covalent. Metallic. Ionic. Isotopic.

54. Compounds with high melting points have Covalent bonds. Metallic bonds. Ionic bonds. No chemical bonds.

55. Minerals A mineral is a naturally occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition. An inorganic substance is one that is not made up of living things or the remains of living things (no carbon). Most rocks that make up the earth’s crust are mixtures of various minerals.

56. Minerals For an Earth material to be considered a mineral, it must have the following characteristics: It must be naturally occurring. It must be a solid substance. It must have an orderly crystalline structure. It must have a definite chemical composition. It must generally be considered inorganic.

57. Which of the following is not a characteristic of minerals? Crystalline structure Formed by inorganic processes Definite chemical composition Either liquid or solid

58. What is a naturally occurring, inorganic solid with an orderly crystalline structure and a definite chemical composition? A mineral An element An isotope A compound

59. Why is ice in a glacier considered to be a mineral, but water from a glacier is not? Water is not naturally occurring. Water does not have a chemical composition. Ice is not naturally occurring. Ice is a solid, but water is not.

60. Minerals There are four major processes by which minerals form: Crystallization from magma. Magma = molten rock. Ex: Feldspar, Quartz, Muscovite, and Hornblende. 2. Precipitation. Minerals from water on Earth. Ex: Halite and Calcite. 3. Changes in pressure and temperature. Increase in pressure = recrystallization of mineral. Change in temperature = new minerals formed. Ex: Talc and Muscovite. 4. Formation from hydrothermal solutions. Hydrothermal solution = very hot mixture of water and dissolved substances (100° - 300°C). When solution comes in contact with existing minerals, chemical reactions take place to form new minerals. Ex: Quartz and Pyrite.

61. Minerals form from bodies of water due to the process of Condensation. Precipitation. Melting. Cooling.

62. The process of mineral formation from magma is called Evaporation. Precipitation. Crystallization. Melting.

63. Mineral formation caused by high pressures and high temperatures would most likely occur in which of the following environments? A lava flow The ocean A cave Deep within the Earth

64. Minerals Earth scientists have identified more than 3,000 different minerals, but fewer than 20 of them are common. The common minerals are called rock-forming minerals because they form the rocks of the earth’s crust. Of the 20 rock-forming minerals, 10 are so common that they make up 90% of the mass of the earth’s crust. These minerals are: quartz, orthoclase, plagioclase, muscovite, biotite, calcite, dolomite, halite, gypsum, and ferromagnesian minerals, which includes olivines, pyroxenes, and amphiboles. Common minerals, together with thousands of others that form on Earth, can be classified into groups based upon their composition.

65. Minerals All minerals can be classified into two main groups based on their chemical composition. Silicate Minerals. Contain silicon. Make up 96% of the earth’s crust 2. Nonsilicate Minerals Do not contain silicon. Make up 4% of the earth’s crust.

66. Minerals are classified by Color. Composition. Size. Density.

67. Minerals Silicate Minerals: Silicon and oxygen combine to form a structure called the silicon-oxygen tetrahedron. Consists of one silicon atom and four oxygen atoms. The silicon-oxygen bonds are very strong. It provides the framework of every silicate mineral. Silicate minerals provide scientists with clues about conditions in which the minerals were formed. It can join in a variety of ways.

68. Minerals

69. Minerals Based on their chemical composition, nonsilicate minerals are classfied into five major groups: Carbonates, halides, native elements, oxides, sulfates and sulfides.

70. Minerals Carbonates are compounds that contain a carbonate group (CO3). Second most common mineral group. Ex: Dolomite, Calcite, Limestone, and Marble.

71. Minerals Oxides are compounds that contain oxygen and an element other than silicon (usually metals). Ex: Corundum, Hematite, and Rutile.

72. Minerals Sulfates are compounds that contain a sulfate group (SO4). Ex: Gypsum and Anhydrite. Sulfides are compounds that consist of one or more elements combined with sulfur. Ex: Galena and Pyrite.

73. Minerals Halides are compounds that consist of chlorine or fluorine combined with sodium, potassium, or calcium. Ex: Halite and Fluorite.

74. Minerals Native Elements are elements uncombined with other elements. Ex: Silver, Copper, Gold, Carbon, and Sulfur.

75. A mineral that contains carbon, oxygen, and the metallic element magnesium would be classified as a (an) Silicate. Oxide. Carbonate. Sulfate.

76. The building block of the silicate minerals is called the Silicon-oxygen tetrahedron. Aluminum-oxygen tetrahedron. Silicon-oxygen triangle. Silicon-aluminum triangle.

77. All minerals in the sulfate and sulfide groups contain what element? Silicon Sulfur Oxygen Carbon

78. The most common mineral group in Earth’s crust is the Oxides. Carbonates. Sulfides. Silicates.

79. To which mineral group does orthoclase feldspar (KAlSi3O8) belong? The oxides. The carbonates. The silicates. The halides.

80. Properties of Minerals Earth scientists called mineralogists conduct tests with special equipment to properly identify minerals. Mineralogists work in laboratories and in the field to identify minerals – from the most common to the most rare and precious. Each mineral has specific properties that are a result of its chemical composition and crystal structure. These properties provide useful clues for identifying minerals. You can identify some of these properties by simply looking at a sample of the mineral. You can determine other properties through simple tests.

81. Properties of Minerals Color A property you can easily observe is the color of a mineral. Some minerals have very distinct colors. Color alone is not a reliable clue in identifying a mineral sample. Many minerals are similar in color, and very small amounts of certain elements may greatly affect the color. Color is also an unreliable identification clue because weathered surfaces may hide the color of minerals. When you examine a mineral for color, be sure to inspect a freshly exposed surface.

82. Which of the following properties is generally the least useful in identifying minerals? Hardness Streak Cleavage Color

83. The color of a mineral, such as fluorite, changes due to Small amounts of different elements. Differences in the hardness. Differences in the crystal structure. Differences in the density.

84. Properties of Minerals Streak A more reliable clue to the identity of a mineral is the color of that mineral in powdered form, which is called its streak. The easiest way to observe the streak of a mineral is to rub some of the mineral against a piece of unglazed ceramic tile called a streak plate. Because the streak is the powdered form of the mineral, it may not be the same color as the larger piece of the mineral. Metallic minerals generally have a dark streak. For most nonmetallic minerals, the streak is either colorless or a very light shade of the normal color of the mineral.

85. The color of the powdered form of a mineral is called Cleavage. Streak. Luster. Fracture.

86. Properties of Minerals Luster Light reflected from the surface of a mineral is called luster. Minerals that reflect light like polished metal are said to have a metallic luster. Al other minerals have a nonmetallic luster. Mineralogists distinguish several types of nonmetallic luster. Transparent quartz and other minerals that look like glass have a glassy luster. Minerals with an appearance like the surface of candle wax have a waxy luster. Some minerals, such as the micas, have a pearly luster. Diamond is an example of a mineral with a brilliant luster. A mineral that lacks luster of any kind of shine has a dull (earthy) luster.

87. The appearance or quality of light reflected from the surface of a mineral is called Streak Color Cleavage Luster

88. Properties of Minerals Crystal Form The visible expression of a mineral’s internal arrangement of atoms. Every mineral has a distinct crystal form. Mineral crystals will form in one of six basic shapes.

89. Properties of Minerals

90. Properties of Minerals Hardness The measure of the ability of a mineral to resist scratching is called hardness. Geologists use a standard hardness scale called the Mohs Scale (Figure 19, Page 52). Any mineral of unknown hardness can be rubbed against these to determine its hardness. Other objects (fingernail, penny, glass, etc.) can also be used to determine hardness.

91. Properties of Minerals

92. The resistance of a mineral to being scratched is called Streak Fracture Hardness Cleavage

93. Mohs scale is used to determine what property of minerals? Cleavage Density Hardness Luster

94. What is the hardness of an unknown mineral that scratches glass, but will not scratch quartz? 5.0 7.5 6.0 8.0

95. Properties of Minerals Cleavage The tendency of a mineral to cleave, or break, along flat, uneven surfaces. Some minerals tend to split easily along certain flat surfaces. The surface along which cleavage occurs runs parallel to a plane in the crystal where bonding is relatively weak. Mineralogists use cleavage to identify and describe some minerals.

96. The tendency of minerals to break along smooth flat surfaces is called Fracture. Cleavage. Streak. Crystal form.

97. Properties of Minerals Fracture Many minerals do not break along cleavage planes. Instead, they fracture, or break, unevenly into curved or irregular pieces. Mineralogists describe a fracture according to the appearance of the broken surfaces. For example, a rough surface is called uneven or irregular. A broken surface that looks like a piece of broken wood is called splintery or fibrous. Curved surfaces on a fractured mineral are called conchoidal.

98. What is the uneven breakage of a mineral called? Fracture. Cleavage. Crystal form. Hardness.

99. What determines whether a mineral will show cleavage or break in irregular fractures? Hardness. External shape. Internal atomic structure. Density.

100. Properties of Minerals Density When handling equal-sized specimens of various minerals, you may notice that some feel heavier than others. One way to compare these minerals is to lift, or heft, mineral samples of the same size. A more precise comparison can be made by measuring the density of a sample. Density is the ratio of the mass of a substance to its volume. Density = Mass/Volume The units of density are grams per cubic centimeter (g/cm3).

101. Properties of Minerals The density of a mineral depends on the kinds of atoms it contains and how closely they are packed. Most of the common minerals in the earth’s crust have densities in the narrow range between 2 and 3-g/cm3. The densities of minerals containing such heavy metals as lead, uranium, gold, and silver range from 7 to 20-g/cm3. Therefore, density helps identify the heavier minerals more readily than it does the lighter ones.

102. What is density of a mineral? The ratio of a mineral’s mass to its volume. The ratio of a mineral’s height to its weight. A mineral’s mass. A mineral’s volume.

103. What is the density of a mineral with a mass of 41.2 grams and a volume of 8.2 cm3? 337.8 g/cm3 49.4 g/cm3 5.02 g/cm3 0.19 g/cm3

104. How could you determine if a sample of gold is pure? Compare the sample’s density with that of pure gold. Compare the sample’s color with that of pure gold. Determine whether the sample is magnetic. Determine whether the sample will fizz in contact with hydrochloric acid.

105. Properties of Minerals Special Properties of Minerals All minerals exhibit the properties already described, in addition, a few minerals have some special properties that can aid in their definition. Magnetism. Mineral is attract to a magnet. Fluorescence or Phosphorescence. Ability to glow under ultraviolet light = Fluorescence. Minerals that continue to glow = Phosphorescence. Double Refraction. Bend light in such a way that they produce a double image of any object viewed through them. Radioactivity. Results are unstable nuclei decay over time into stable nuclei by releasing particles and energy. 5. Distinctive Feel. Some minerals feel soapy, other greasy. 6. Distinctive Smell. Some minerals smell when in powdered form.

106. Properties of Minerals A mineral’s properties depend on the elements that compose the mineral (composition) and its structure (Arrangement of atoms). Table 2 on page 54 + 55 in your text list some of the more common minerals and their properties.

107. Which of the following minerals will fizz in contact with hydrochloric acid? Quartz Calcite Fluorite Gold

108. What property can be used to distinguish talc and gypsum? Talc has a soapy feel. Gypsum has a soapy feel. Talc fizzes with hydrochloric acid. Gypsum can scratch glass.

109. What determines the properties of a mineral? Size and shape. Composition and age. Composition and structure. Structure and size.