Atoms to Minerals

1. Atoms to Minerals Matter and Atoms Chapter 5.1

2. Matter What is matter? Matter is anything that has mass and volume. Mass is the amount of material in an object or a substance. Volume is the amount of space taken up by an object or a substance. A sample of earth material � has mass and volume therefore is matter. All matter is made of particles so small that they cannot be seen even with a powerful microscope. There are only about 100 kinds of these tiny particles, which make up the thousands of substances that occur in Earth�s crust.

3. Matter All matter is composed of elements. An element is a substance that cannot be broken into simpler substances by ordinary chemical means. Oxygen & Nitrogen are elements in the atmosphere. Gold, Silver, & iron are metallic elements. Symbol � abbreviation of the elements name. Usually the 1st letter of the elements name. What makes up elements? More than 150 years ago the English chemist John Dalton stated his concept of the particle model � that each element is made up of tiny particles. Dalton defined the atom as the smallest part of an element that has all the properties of that element.

4. Structure of an Atom Electrons � moving charged particles There motion creates a cloud of charge surrounding the nucleus. The nucleus of an atom contains protons and neutrons. Each proton has an electric charge, but it is unlike that of the electron. Electron�s charge is negative and the proton�s charge is positive. The amount of the protons charge is exactly equal to the electrons negative charge. The neutron carries no charge.

5. Structure of an Atom The atom is electrically neutral, since protons and electrons have equal but opposite charges. The atom is tiny. Most of the volume is empty space. The tiny space contains the more massive atomic particles.

6. The Nucleus atomic number � the number of protons in an atom. The proton is 1836 times heavier than the electron, and the neutron is slightly heavier than the proton. More than 99.9 % of the mass of an atom is in its nucleus.

7. Classifying Atoms mass number � of the element gives the average number of protons and neutrons in an atom. number of neutrons = mass number � atomic number Isotopes � atoms of the same chemical element with different mass numbers. Hydrogen � has three isotopes Uranium � has a number of isotopes

8. Bonding of Atoms Compound � is a substance that contains two or more elements chemically combined. The kind of attachment where electrons are shared by atoms is called a covalent bond. Ion � an atom in a charged condition, either negative(nonmetals) or positive(metals). Ionic Bond � force of attraction, between the oppositely charged ions hold them together. Metallic Bonds � the free movement of electrons around metal ions.

9. Compounds and Mixtures Molecule � the smallest part of a compound that still has all the properties of that compound. Compounds should not be confused with mixtures. Mixture � the individual elements or compounds keep their own properties and can be present in any proportions. Most mixtures can be separated easily by physical means.

10. Atoms to Minerals Composition and Structure of Minerals Chapter 5 Section 2

11. What is a mineral? A Mineral: 1. occurs naturally 2.��is a solid 3.��has a definite chemical composition(elements are combined in definite proportions) 4.��has its atoms arranged in an orderly pattern 5.��is inorganic (it was not formed by any process involving plants, animals, or other organisms)

12. What is a mineral? �Over 4,000 known minerals. Quartz, halite(rock salt), gold, and diamond Water not a mineral not a solid. Glass not a mineral because it doesn�t occur naturally. Coal is not a mineral because it was made from plant remains.

13. What is a mineral? Of all the elements in the Earth�s crust, a mere eight make up 98.5% of the crust�s total mass. 2 most abundant elements oxygen and silicon, are found in more than 90% of the minerals in the crust. Most minerals are compounds. Ex. Quartz (Si & O) Native Elements � consist of single elements. Ex. Silver, Copper, Sulfur, & Diamond Rocks consist of a mixture of minerals.

14. How Minerals Form Minerals form in several ways. Some form out of molten earth material, or magma. The rate of which magma cools determines the size of the mineral grains that form. Some minerals form when water evaporates that contained dissolved ions. (Halite forms when salt water evaporates). Minerals can also be changed into different minerals by heat, pressure, or the chemical action of water.

15. Structure of Minerals All minerals have crystalline structure, a regular, orderly arrangements of atoms. Minerals are often found in the form of beautiful crystals. Crystal � a regular geometric solid with smooth surfaces called crystal faces. the orderly arrangement of ions determines the shape of the crystal. There are six basic crystal systems.

16. Silicates More than 90% of the minerals in Earth�s crust are members of a mineral family called silicates. These are compounds of elements silicon and oxygen, plus one or more metallic element, such as aluminum or iron. The unit is held together by covalent bonds between the silicon atom and oxygen atoms. If the imaginary lines are drawn to connect the centers of the four oxygen atoms, they make a geometric figure called a tetrahedron. Because the silicon atom is in the center, it�s known as the silica tetrahedron.

17. Crystal Structure and Physical Properties Increased temperatures can weaken the bond between particles. The melting point of a mineral is sometimes used to determine minerals similar in appearance. Cleavage � a minerals tendency to split in particular directions. Weak bonds allow a mineral to split easily (mica) A strong network of bonds such as quartz, prevent splitting.

18. Crystal Structure and Physical Properties The hardness of a mineral depends on the arrangement of its ions or atoms and the strength of the electric forces among them. (Ex. Carbon; one arrangement carbon forms diamonds, the hardest natural mineral, diamonds have a tetrahedral network of carbon atoms.; in another carbon forms graphite, a very soft mineral that flakes easily, graphite has carbon atoms arranged in sheets.) Because of the atoms arrangement, the Diamond has a greater density than Graphite.

19. Atoms to Minerals Identifying Minerals Section 5.3

20. Rock-Forming Minerals Mineralogy - The study of minerals and their properties. Rock-Forming Minerals � A specific group of minerals known to make up most rocks. Only about 30 minerals of the 4,000 are common. Most common: Quartz, Feldspar, Mica and Calcite.

21. Identifying Minerals by Inspection Color � the most easily observed mineral property, but it is the least useful property for mineral identification. Three reasons why color is unreliable: 1. Impurities 2. Too many minerals have the same color. 3. Minerals can change color.

22. Identifying Minerals by Inspection Luster � the way a mineral shines in light. Metallic or Nonmetallic Metallic Luster � Shine like polished metal Galena and pyrite Nonmetallic Luster Vitreous � shiny glass, Greasy, Oily, Dull, Earthy Crystal Shape � Regularly shaped crystals are difficult to find.

23. Testing Mineral Specimens Physical Tests � Streak, cleavage, hardness, and specific gravity. Streak � the color of the minerals powder. The streak is not always the same color as the mineral. The streak of nonmetallic minerals are usually colorless or white. Metallic minerals have streaks at least as dark as the specimen.

24. Testing Mineral Specimens Cleavage vs. Fracture Cleavage � A minerals tendency to split easily along flat surfaces. (Mica & Feldspar) Fracture � breaks in directions other than along cleavage surfaces. (Quartz & Copper) Conchoidal � shell-like, Splintery � jagged surface, Uneven or Irregular � rough surface

25. Testing Mineral Specimens Hardness � its resistance to being scratched. Mohs Scale � ten well-known minerals assigned numbers from 1 to 10. (Softest to Hardest) The scale is not uniform, each number is several times harder than the last. Fingernail, copper penny, glass plate, and steel nail. Hardness vs. Brittleness

26. Testing Mineral Specimens Specific Gravity � the ratio of its weight to the weight of an equal volume of water. How many times denser the mineral is than water. Nonmetallic minerals have densities less than metallic minerals.

27. Special Properties of Minerals Characteristics that can confirm a mineral by inspection. Double Refraction � Iceland Spar, Calcite Fluorescent � glow under UV light (Fluorite and calcite) Phosphorescent � glow after UV light is off (Willemite and sphalerite)

28. Special Properties of Minerals Halite (Rock Salt) by taste Magnetite is attracted to a magnet. Carnotite and Uraninite are radioactive. Acid Test � Hydrochloric acid fizzes on calcite. CO2 is released.

29. Atoms to Minerals Mineral Groups Section 5.4

30. Major Silicates More than 90% of minerals are of the Silicate Family in Earth�s crust. Silicate compound (Si, O & one or more metallic elements) Silicates are linked by silica tetrahedrons.

31. Quartz 2nd most abundant mineral in Earth�s crust. Hardness of 7, hardest common mineral. Fracture, glassy or greasy luster. Colors of clear or white, rose, amethyst, and smoky. Found in most sands, Granite, and quartzite. Uses: watches, prisms, heat lamps, lenses, glass, paints, and sometimes jewelry.

32. Feldspars Feldspar Family consists of 60% of the crust. 2 directions of cleavage, Hardness of 6, Pearly luster. Used for glass and ceramics. Orthoclase (Potassium) � Found in Granite Light-colored (pink/salmon) 2 Cleavage surfaces meet at right angles Plagioclase (Sodium-Calcium) Varied color (white to gray) 2 Cleavage surfaces meet at less than a right angle Fine parallel lines mark one cleavage surface - Striations

33. Other Silicates Pyroxene � Cleavage surfaces meet at nearly right angles Augite � 2 cleavage surfaces, Hardness 5 - 6 ferromagnesian silicate � (Fe & Mg) dark color Mica � Soft Silicates, Found in Granite Hardness 2.5, Perfect Cleavage Muscovite � light-colored, Biotite � dark-colored Uses: paints, plastics, rubber, and roofing

34. Other Silicates Amphibole � Found in igneous and metamorphic rocks. Long, needlelike crystals Hornblende � Hardness 5 � 6, 2 cleavage surfaces at oblique angles. Kaolinite � white, hardness 2, 1 perfect cleavage Ceramics, paints, fiberglass Olivine � olive-green, hardness 6.5, glassy, shell- like fracture Used to make jewelry

35. Carbonates Negatively charged carbonate ions bonded to positive metal ions. (1C to 3O) Dolomite � (Ca Mg Carbonate) Hardness of 3.5 � 4, not as much reaction to acid Calcite � (Calcium Carbonate) Most common carbonate, clear or white Hardness of 3, 3 perfect cleavage surfaces Acid Test

36. Oxides and Sulfides Oxide � a mineral consisting of a metal element combined with oxygen. Sulfide � a mineral consisting of a metal element combined with sulfur. Hematite � most common iron oxide, Red, NM, Fracture, Red-brown streak, Hardness 5 � 6 Magnetite � black iron oxide, attracted to magnets, Hardness 5.5 � 6.5 Pyrite � most common iron sulfide, brass to golden yellow, Hardness 6, �fool�s gold�