Chapter 2: Matter and Minerals

What is Matter? Matter – the substance of which any physical object is composed States of Matter: Solid Liquid Gas Controlling factors: Temperature Pressure Examples: Gold Mercury Oxygen solid liquid gas

The stuff that makes up all matter The make-up of solid matter on Earth: Atoms     (smallest) (largest) Elements Compounds Minerals Rocks Atoms: the stuff that builds elements the smallest particle that uniquely defines an element

Atomic Structure Particles that make up an atom: Protons: positive (+) charge Neutrons: no charge Electrons: negative (-) charge Protons + neutrons define the nucleus of an atom. Layers of electrons that orbit around the nucleus are called orbitals or energy-level shells.

Atomic Structure

The stuff that makes up all matter The make-up of solid matter on Earth: Atoms  Elements  Compounds  Minerals  Rocks (smallest) (largest) Elements: fundamental building blocks smallest matter that can’t be broken down

Periodic Table of Elements

Periodic Table of Elements Atomic Number: (# of protons) Atomic Weight = # protons + # neutrons Atomic number = # protons These are called isotopes. Example: (Carbon) 12C 13C 14C Can atoms of the same element have different mass numbers? Yes

Periodic Table of Elements Isotopes: are atoms of the same element with different mass numbers, the number of neutrons changes. Atomic Weight = # protons + # neutrons Atomic number = # protons These are called isotopes. Example: (Carbon) 12C 13C 14C Can atoms of the same element have different mass numbers? Yes

Modeling Atoms Electrons and Their Energy Levels Some Rules to Remember about atoms and their e- A: The inner or first energy shell fills with e- first. B: The 1st energy shell can hole 2e- but no more than 2e-. C: The 2nd energy shell can hold up to 8e- but no more than 8e-. D: the 3rd energy shell can hole up to 18e- but no more than 18e-.

E: The 4th energy shell can hold 32e-. F: the 5th energy shell can hole 50e-. If there are more e- that the energy shell can hole, they “spill” into the next level or shell.

Modeling Atoms The octet rule: says that atoms tend to gain, lose or share electrons so as to have eight electrons in their outer electron shell. The bonding in carbon dioxide (CO2)- all atoms are surrounded by 8 electrons, according to the octet rule. CO2 is thus a stable molecule.

Valence Electrons Electrons in the outermost shell of an atom are called valence electrons; they dictate the nature of the chemical reactions of the atom and largely determine the electrical nature of solid matter. Valence Electrons participate in the formation of a chemical bond;

Modeling Atoms

Atomic Structure Atoms of the same element: have the same number of protons (i.e., same atomic number) can have different numbers of neutrons (referred to as isotopes) can have different numbers of electrons Ion – an atom that has gained or lost an electron

Atomic Structure Types of IONS: CATIONS – a loss of electrons, resulting in a positive (+) charge ANIONS – a gain of electrons, resulting in a negative (-) charge Examples: Na+ (cation) Cl – (anion) NaCl (table salt) chemical compound

Atomic Structure Sodium atom Chlorine atom loses an electron (becomes positively charged) Chlorine atom gains an electron (becomes negatively charged)

Compounds Examples: NaCl H2O Atoms  Elements  Compounds  Minerals  Rocks (smallest) (largest) Definition: A chemical compound consists of elements that combine in a specific ratio. Examples: NaCl H2O The smallest quantity of a compound is called a molecule. Molecules are held together by chemical bonding.

Bonding – chemical matrimony Chemical bonding: formation of a compound by combining two or more elements manner in which electrons are distributed among atoms (valence electrons) In bonded atoms, electrons may be lost, gained, or shared. 4 types of bonding: ionic covalent metallic van der Waals

Bonding – chemical matrimony Ionic bonding: electrons are transferred between atoms forming attracting ions (e.g., NaCl) Na+ Cl–

Bonding – chemical matrimony 1. Ionic bonding: orderly arrangement of oppositely charged ions bonds are moderately strong (salt dissolves in water)

Periodic Table of Elements

Bonding – chemical matrimony 2. Covalent bonding: electrons are shared between atoms generally strong bonds (e.g., diamond, pure C) Chlorine gas molecule, Cl2

Bonding – chemical matrimony 3. Metallic bonding: electrons drift around from atom to atom (e.g., copper, gold, silver) good conductors of electrical current generally weaker, less common than other bonds This is the world's largest Gold Nugget ever found. Discovered in 1872 and is called the Holtermann Nugget. It was 630lbs in weight. Gold, Au

Bonding – chemical matrimony 4. Van der Waals bonding: sheets of covalently bonded atoms held together by weak electrostatic forces very weak bonds examples: graphite, mica

What kind of bonding do you prefer? In a covalent world… In an ionic world…

Compounds (Minerals, Organic Compounds) Atomic Particles Atoms (Elements) Compounds (Minerals, Organic Compounds) Rocks Living Things Earth Biosphere

The stuff that makes up all matter The make-up of solid matter on Earth: Atoms  Elements  Compounds  Minerals  Rocks (smallest) (largest)

Minerals: the building blocks of rocks Definition of a Mineral: naturally occurring inorganic solid characteristic crystalline structure definite chemical composition Definition of a Rock: A solid aggregate (mixture) of minerals

Mineral characteristics Definition of a Mineral: naturally occurring inorganic solid characteristic crystalline structure definite chemical composition steel plastic sugar table salt mercury ice coal no, #1 no, #1 no, #1,2 YES! no, #3 YES! no, #2 basalt obsidian mica gold paper chalk coral no, #5 no, #4 YES! YES! no, #1,2 no, #2 no, #2

Mineral characteristics Naturally formed No substance created artificially is a mineral. examples: plastic, steel, sugar, paper Inorganic Anything formed by a living organism and containing organic materials is not a mineral. examples: wood, plants, shells, coal Solid Liquids and gases are not minerals. examples: water, petroleum, lava, oxygen

Mineral characteristics Characteristic crystalline structure must have an ordered arrangement of atoms displays repetitive geometric patterns in 3-D glass not a mineral (no internal crystalline structure) Definite chemical composition must have consistent chemical formula examples: gold (Au), quartz (SiO2), orthoclase (KAlSi3O8) basalt (like many other rocks) contains variable ratios of different minerals; thus, has no consistent formula

How many minerals are there? Nearly 4,000 types of minerals Only ~30 occur commonly (whew!) Why not more? Some combinations are chemically impossible Relative abundances of elements don’t allow more

Element abundances in the crust All others: 1.5%