Mineral Notes: Basics of Composition and Chemistry
What is a mineral (p 34)
1. Occurs ___naturally___________
2. Is a ____solid_____________
3. Definite chemical ___composition______________
4. Atoms arranged in an orderly _______pattern______________
5. Is ____inorganic_____ – not formed by a process involving plants, animals or other organisms
Minerals are made of atoms (p. 30-32), and (p 35)
1. Atom Basics
a. Proton – located in Nucleus, positively charged subatomic particle
b. Neutron – located in Nucleus, no charge
c. Electron – located outside of nucleus negatively charged
2. Atomic Number – number of protons in the nucleus of an atom
3. Atomic Mass – sum of protons and neutrons in the nucleus
4. Isotopes
Elements in the crust (based on mass)
FACTOIDS:
46 .0% __Oxygen____________
The Crust is made mostly of Silicate Minerals
27.0 % ___Silicon__
Silicates are based on – Silicon dioxide - SiO2
8.0 % ___Aluminum_____
SiO2 (Quartz) is the main mineral in beach sand
5.0 % ___Iron__
3.6 % ___Calcium____
2.8%
____Sodium___
2.6%
___Potassium__
O SiAl FeCal NaK Mg
2.1 % __Magnesium___
What atoms do scientists think are in the Earth’s core?
(They’re not the same as the atoms in the crust)
Iron and Nickel
Inner Core = Solid
Outer Core = liquid – generates magnetic shield
Atoms can combine to form minerals in different ways
Atoms combine by “bonding” with one another. All bonding between atoms involves the sharing or transfer of
the outermost __electrons_______.
Bonding (p 35 – 36)
1. Atoms bond in order to maximize the spread of energy. The most “comfortable” arrangement for an atom
is when it has eight electrons in its outermost shell. Atoms will often transfer or share electrons so that they
can obtain exactly eight electrons in the valence shell. An atom with eight electrons in the shell is said to
have an _octet___.

Interesting fact – atoms that already have an octet are relatively unreactive, and are
called “noble gases” because they don’t associate with other atoms
(light bulb demo)
2. Atoms can obtain an octet by “BONDING” with other atoms in two general ways:
a. by transferring electrons.
b. by ___sharing___ electrons.
3. Four general types of bonds are listed below:
a. M_etallic
b. C_ovalent__
c. I__onic___
d. P_olyatomic__ Ions
METALLIC BONDS:
A. Valence electrons wander freely
through metal. Metal consist of a
clump of positive atom nuclei
held together by negativelycharged electron "glue" between
them.
B. Electrons can move rapidly in
response to electric fields, hence
metals are good conductors of
electricity.
C. Electrons can transmit kinetic energy rapidly; hence metals are good conductors of thermal energy.
D. The layers of atoms in metal are hard to pull apart because of the electrons holding them together, so metals are
tough. But individual atoms are not held to any other specific atom, and can slip easily past one another, so metals
are ductile.
COVALENT BONDS: When two Nonmetal atoms share electrons they create __covalent_ Bonds. Atoms
bonded by sharing electrons are called molecules. The most common mineral with covalent bonds is silicon
dioxide (quartz).
Diamond is one of the hardest minerals. Diamond is composed of carbon atoms held together by covalent bonds
Graphite is one of the softest minerals. Graphite is composed of carbon atoms held together by covalent bonds.
What do you see that is different between the structure of graphite and diamond that might
account for their different hardness?
In diamond all the bonds between carbon atoms are strong (covalent), but in graphite the bonds
between atoms of different layers are weak (not covalent)
IONIC BONDS: When a Metal and a Nonmetal atoms get together the atoms will gain or lose electrons to
achieve an octet, creating __ionic_ Bonds.
Sodium and Chlorine; valence electron transfer: NaCl. The Positive and Negative ions attract one another: Na+
and Cl-
Count the electrons and examine the charge in the valence shells for the sodium and chlorine before and after forming the
ionic bond:
Electrons in Valence Shell
Charge on the atom
BEFORE BONDING
Sodium
Chloride
AFTER BONDING
Sodium
Chloride
After the bonds have formed, the sum of all positive and negative charges must be __zero___ in an ionic compound
Most minerals have a combination of many types of bonds. The properties of minerals are totally related to the type and
number of bonds between the atoms:
1.
What is the Mohs hardness number for the softest minerals?
2.
What are three very soft minerals?
3.
What bonding characteristics do the softest minerals have in common?
4.
What is the Mohs hardness number for the hardest minerals?
5.
What are three very hard minerals?
6.
What bonding characteristics do the hardest minerals have in common?
7.
What is unique about the bonds in pure metals that make their hardness between 2 and 5 on Mohs scale?
8.
What type of bonds do the hardest minerals have?