Download Minerals: Physical Properties Lecture

Chapter 2: Matter and Minerals
What is Matter?
• Matter – the substance of which any physical
object is composed
States of Matter:
• Solid
• Liquid
• Gas
Examples:
Controlling factors:
• Temperature
• Pressure
Gold
Mercury
Oxygen
solid
liquid
gas
The stuff that makes up all matter
• The make-up of solid matter on Earth:
Atoms  Elements  Compounds  Minerals  Rocks
(smallest)
(largest)
• 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)
• Elements:
– fundamental building blocks
– smallest matter that can’t be broken down
(largest)
Periodic Table of Elements
Periodic Table of Elements
Atomic Number: (# of protons)
Atomic Weight = # protons + # neutrons
Atomic number = # protons
Can atoms of the same element have
different mass numbers?
Yes
These are called isotopes.
Example: (Carbon)
12C 13C 14C
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
Can atoms of the same element have
different mass numbers?
Yes
These are called isotopes.
Example: (Carbon)
12C 13C 14C
Modeling Atoms
Electrons and Their Energy Levels
Some Rules to Remember
about atoms and their eA: 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 8ebut no more than 8e-.
D: the 3rd energy shell can hole up to 18ebut 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
loses an electron
Chlorine atom
gains an electron
(becomes positively
charged)
(becomes negatively
charged)
Compounds
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
Chlorine gas molecule, Cl2
– generally strong
bonds
(e.g., diamond, pure C)
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…
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:
1.
2.
3.
4.
5.
naturally occurring
inorganic
solid
characteristic crystalline structure
definite chemical composition
steel
no, #1
plastic
no, #1
sugar table salt
no, #1,2
YES!
basalt
no, #5
obsidian
no, #4
mica
YES!
gold
YES!
mercury ice
no, #3 YES!
paper
chalk
no, #1,2 no, #2
coal
no, #2
coral
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%