Chapter 2 Minerals Section 1 & 2 Matter and Minerals Notes 2-1

Elements and the PT An element is a substance that cannot be broken down into simpler substances by chemical or physical means. Most common elements in the crust Oxygen – 47% Oxygen – 47% Silicon – 28% Silicon – 28% Aluminum – 8% Aluminum – 8% Iron – 5% Iron – 5% Calcium – 4% Calcium – 4% Sodium – 3% Sodium – 3% Potassium – 3% Potassium – 3% Magnesium – 2% Magnesium – 2%

Atoms An atom is the smallest particle of matter that contains the characteristics of an element. Nucleus Made of protons (+) and neutrons (no charge) Made of protons (+) and neutrons (no charge) Atomic number = number of protons in nucleus Atomic number = number of protons in nucleus

Atoms Electrons Same number as protons Same number as protons Smallest subatomic particle Smallest subatomic particle Super fast Super fast Found in energy levels around the nucleus Found in energy levels around the nucleus

Why Atoms Bond A compound is a substance that consists of two or more elements that are chemically combined in specific proportions. Hook together using the electrons Hook together using the electrons When an atom’s outermost energy level does not contain the maximum number of electrons, it will form a chemical bond with one or more atoms.

Isotopes Atoms with the same number of protons but different numbers of neutrons are isotopes of an element. Mass number = protons + neutrons C-12 (6 p & 6 n) – 99% of all carbon on earth C-12 (6 p & 6 n) – 99% of all carbon on earth C-13 (6 p & 7 n) – remainder of natural carbon on earth C-13 (6 p & 7 n) – remainder of natural carbon on earth C-14 (6 p & 8 n) – very little; used to find age of once living things C-14 (6 p & 8 n) – very little; used to find age of once living things

Isotopes Radioactive Decay: Unstable nuclei Unstable nuclei Forces that hold nucleus together are not strong enough Forces that hold nucleus together are not strong enough Radiate energy and particles Radiate energy and particles Certain radioactive atoms can be used to determine ages of fossils, rocks and minerals Certain radioactive atoms can be used to determine ages of fossils, rocks and minerals

Types of Bonds Ionic Bond Form between positive and negative ions Form between positive and negative ions Ion: charged atom because of electron gain or loss Ion: charged atom because of electron gain or loss High melting and boiling points High melting and boiling points NaCl (sodium chloride) NaCl (sodium chloride) Salt or Halite

Types of Bonds Covalent Bond Form when atoms share electrons Form when atoms share electrons Low melting and boiling points Low melting and boiling points Water is covalent Water is covalent Boils at 100 degrees C Halite boils at 1413 degrees C Molecule = smallest particle of a covalent compound; neutral charge Molecule = smallest particle of a covalent compound; neutral charge Ex: gases that make up earth’s atmosphere Ex: gases that make up earth’s atmosphere

Types of Bonds Metallic Bonds Form when electrons are shared by metal ions Form when electrons are shared by metal ions These bonds give metals their properties These bonds give metals their properties Malleable, ductile

What is a Mineral? Mineral: a natural, inorganic, crystalline solid Inorganic: not made of a living thing or the remains of a living thing Inorganic: not made of a living thing or the remains of a living thing Crystalline (crystal): natural solid with a definite internal structure Crystalline (crystal): natural solid with a definite internal structure Every mineral has a specific chemical make up; can be a element or compound Every mineral has a specific chemical make up; can be a element or compound Rocks are not minerals; minerals are not rocks Rocks are not minerals; minerals are not rocks Rocks are made up of various minerals and organic matter

Quartz Orthoclase feldspar (K-spar) Plagioclase feldspar Muscovite mica

Biotite mica Calcite Dolomite Halite

Gypsum Olivine Pyroxene - Augite Amphibole - Hornblende

What makes a mineral, a mineral? Must answer yes to four important questions 1. Is this substance made of inorganic material? 2. Does this substance occur naturally? 3. Is this substance a solid in crystalline form? 4. Does this substance have definite chemical composition?

How Minerals Form Crystallization from Magma Magma is molten rock Magma is molten rock As magma cools, minerals crystallize As magma cools, minerals crystallize First = rich in Fe, Mg, Ca Last = Na, K, Al

How Minerals Form Precipitation As the water on Earth evaporates, minerals can precipitate out As the water on Earth evaporates, minerals can precipitate out Temperature changes can cause precipitation Temperature changes can cause precipitation Solid falls out of the water Creates the mineral formation Ex: halite and calcite Ex: halite and calcite

How Minerals Form Pressure and Temperature Increasing pressure can cause minerals to recrystallize while still solid Increasing pressure can cause minerals to recrystallize while still solid Atoms rearrange to form more compact minerals Temperature change can cause minerals to become unstable Temperature change can cause minerals to become unstable New minerals are formed that are more stable at that temperature Ex: muscovite and talc Ex: muscovite and talc

How Minerals Form Hydrothermal Solutions Very hot mixture (100 °C to 300 °C) of water and dissolved substances Very hot mixture (100 °C to 300 °C) of water and dissolved substances Chemical reactions cause new minerals to form Chemical reactions cause new minerals to form Ex: pyrite, quartz, chalcopyrite Ex: pyrite, quartz, chalcopyrite

Silicate Minerals All silicates contain silicon and oxygen Quartz is purely silicon and oxygen Quartz is purely silicon and oxygen Other minerals have one or more different elements attached to the silicon and oxygen Feldspars are the most common silicate minerals Feldspars are the most common silicate minerals Orthoclase feldspar has potassium (K) attached to Si and O Plagioclase feldspar has sodium (Na) or calcium (Ca)

Silicate Minerals Ferromagnesian minerals Rich in magnesium (Mg) and iron (Fe) Rich in magnesium (Mg) and iron (Fe) Include olivine, pyroxene, amphibole and biotite Include olivine, pyroxene, amphibole and biotite Silicate minerals make up 96% of earth’s crust Feldspar and quartz make up 50% of the crust

Crystalline Structure Crystal: natural solid with a definite internal pattern If unrestricted, a mineral will naturally form into a single, large crystal If unrestricted, a mineral will naturally form into a single, large crystal However, most often in natural crystal are not unrestricted However, most often in natural crystal are not unrestricted Most form in tiny crystal shapes that must be seen with a microscope Shapes can be helpful in the identification of a mineral Shapes can be helpful in the identification of a mineral

Crystalline Structure Structure of silicate minerals always begins with the silicon-oxygen tetrahedron One Si to Four O Combined in many different ways to produce different minerals

Nonsilicate Minerals 4% of the earth’s crust Minerals that do not contain silicon (Si) Minerals that do not contain silicon (Si) Six major groups of nonsilicates (p ) Carbonates (CO 3 ) - calcite Carbonates (CO 3 ) - calcite Halides (Cl or Fl combined with Na, K or Ca) - halite Halides (Cl or Fl combined with Na, K or Ca) - halite Native Elements (uncombined) – sulfur, gold Native Elements (uncombined) – sulfur, gold Oxides (O and some other element besides Si) - hematite Oxides (O and some other element besides Si) - hematite Sulfates (SO 4 ) - gypsum Sulfates (SO 4 ) - gypsum Sulfides (one or more elements with S) - galena Sulfides (one or more elements with S) - galena