1. Earth Materials: Minerals

2. Chapter 5. Patterns in Nature: Minerals Today’s Lecture:
1. Minerals: Why care?
2. Atoms, ions & isotopes of the elements
3. Atomic bonding and the formation of chemical compounds
4. Minerals: the building blocks of rocks
Internal structure in relationship to physical properties
5. Introduction to rocks.
Today’s Lecture:

3. Minerals: Why care?
Raw materials for nearly all of the manufactured products we use are obtained from minerals.
Examples:
Aluminum: Soft drink cans
Graphite (Carbon): Pencil lead and lubricant
Copper: Electrical components and wire
Talc: Baby powder
Silver, gold, gemstones: Jewelry
Silicon: Computer chips

4. Malachite: Ore of copper and a gemstone.

5. Quartz: Source of silicon used in making computer chips

6. Galena: Ore of lead

7. Gemstones!

8. Minerals: Why Care? Other reasons:
Rocks inform us about geologic hazards, such as volcanic eruptions, earthquakes etc., enabling us to make better decisions about how we interact with the Earth and use its resources (e.g. siting and designing buildings).
Rocks hold important clues for understanding processes of weathering and erosion. This information can help us use the Earth’s resources more effectively (e.g. extraction of mineral and petroleum resources, soil conservation, degradation of concrete structures, etc.).
Rocks enable us to understand our past & place our lives in proper evolutionary context.
Other reasons:

9. Understanding Matter…
To understand minerals we need to understand matter and how it is organized.
The three states of matter:
Solid
Liquid
Gas

10. States of Matter
Solids-Atoms and molecules organized into fixed structures with a defined shape (crystals, glass, plastics). Atoms move (vibrate) even in a solid! Just limited in a solid.
Liquids-Fluid mixtures of atoms and molecules existing as charged atoms or molecules (e.g. “ions”). Atoms in solutions can form loose associations with each through transient electronic “bonds”. However, the liquid lacks a fixed structure, like that seen in most solids.
Gases-Fluids in which atoms and molecules are in rapid motion, freely moving about with no fixed structure. Gases expand to fill the available space.

11. Atoms, elements and compounds: Building blocks of minerals
Bulding blocks of minerals
(See Science Toolbox 5.1, page 112 of text)
Elements: Different types of atoms that, in their pure form, cannot be divided into other smaller units without changing their properties.
Atom: Smallest division of an element, that still possesses the chemical properties unique to the element.
Compounds: Two or more atoms bonded together. May be composed of atoms of the same element, or combinations of several different elements.

12. Understanding Matter…
What is an atom?
An atom is made up of:
A nucleus: Central region of atom where most of
the mass resides. Comprised of protons and neutrons.
Orbiting electrons: High-speed nearly “massless”
particles of negative charge which orbit the nucleus.
electrons
nucleus

13. Understanding Matter…
Nucleus contains:
Protons = Particles with a mass of 1.0 and a
positive electrical charge.
Neutrons = “ “ a mass of 1.0 and a
neutral electrical charge. Neutrons may
be thought of as a proton bound to an
electron.
Orbiting the nucleus are electrons having essentially no mass ands a negative charge.
neutrons
electrons
A single
atom
protons

14. A simple “ Bohr” model for a single atom:
Understanding Matter…
A simple “ Bohr” model for a single atom:
T&L: Figure 2.4 A

15. ...in reality Structure of an Atom T&L: Figure 2.4 B
Nucleus of protons
and neutrons
T&L: Figure 2.4 B

16. Types of Atoms and Elements
Number of protons in the
nucleus of an element is called
Its atomic number.
Elements are distinguished from each other by their atomic number.
Model of
one atom
nucleus
Examples: All Helium atoms have 2 protons
“ Carbon “ “ “
“ Uranium “ “ “

17. Mass Variations in Elements:
Isotopes: Same element, different mass
Mass Variations in Elements:
The number of protons plus the number of neutrons in the nucleus defines the atomic mass of the element.
However, most elements come in different “species”- versions that differ slightly in mass because of having different numbers of neutrons in the nucleus.
These “species”of elements are called isotopes.

18. Isotopes: Atoms that vary in the number of neutrons in the nucleus
Again… mass variations of the same element are
called “isotopes”.
Many isotopes are unstable, and disintegrate
through a process called radioactive decay
where particles and/or energy are emitted
from the nucleus C 14
Example: Carbon-14
is unstable
The rate of radioactive disintegration is constant, so
they can be used as a kind of clock for dating rocks!

19. Classifying the Elements
Let’s review using Carbon as an example:
Number of protons determines the type of atom
6 protons = carbon
Number of neutrons in an atom can vary.
Number of neutrons plus the number of protons equals the atomic “mass”.
Here are the three isotopes of Carbon:
6 protons & 6 neutrons: mass number = 12
6 protons & 7 neutrons: mass number = 13
6 protons & 8 neutrons: mass number = 14
How we write it
12C
13C
14C

20. Elements are classified by the number of protons
in the nucleus (I.e., their atomic number)
Periodic table of the elements
equals # of protons
6 => 6 protons

21. Classifying the Elelemnts
112 known elements
Only 92 occur naturally

22. Classifying the Elements
You’ve heard of many of these elements, for example:
Helium
Hydrogen
Oxygen
Aluminum
Iron
Titanium
Calcium
Gold

23. Atoms that lose or gain electrons develop a charge.
Ions: Charged Atoms
Atoms that lose or gain electrons develop a charge.
When atoms give away or gain electrons, they
are no longer electrically neutral. In other words,
They take on an electrical charge.
Any atom possessing a charge is called an “ion”.
Atoms with a positive charge are called “cations”.
Those with a negative charge are called “anions”.

24. Internal (“atomic”) structure
Making Minerals
~ 4000 minerals on Earth!
Different elements combine to make chemical compounds…
Example 1: water (2 hydrogen atoms + 1 oxygen atom = H2O)
Example 2: salt (1 sodium atom + 1 chlorine atom = NaCl)
Minerals are naturally-occurring compounds that are classified by their:
Chemical composition
Internal (“atomic”) structure

25. Chemical formula for quartz is: SiO2
Example: Quartz
Quartz contains:
silicon (Si) and
oxygen (O)
element
name
symbol
Chemical formula for quartz is: SiO2

26. 4. Possess an orderly internal structure
What are minerals?
Definition of a mineral:
-> To be considered a mineral, it must:
1. Occur naturally
2. Be inorganic
3. Be a solid
4. Possess an orderly internal structure
5. Have a defined chemical composition

27. Making Compounds Atomic Bonding
How do different elements combine to form compounds?
=> By bonding between atoms!
3 main ways:
“Ionic bonding” - loaning electrons
“Covalent bonding” - sharing electrons
“Metallic bonding” - electrons are free to move about from atom to atom

28. The atoms bond based on these charge differences.
Atomic Bonding
Ionic Bonding
Example: Table Salt: Sodium (Na) and Chlorine (Cl)
Sodium gives up an electron becoming
a positively-charged charged cation.
Chlorine picks up the electron
from Sodium taking becoming
a negatively charged anion.
The atoms bond based on these charge differences.

29. Example: Sodium (Na) and Chlorine (Cl)
Ionic Bonding
Example: Sodium (Na) and Chlorine (Cl)
Atoms arrange in orderly fashion: w/ alternating sodium and chlorine
atoms, so each negative ion is surrounded by positive ions, and visa versa.

30. Crystal Form Reflects Internal Structure
Example: Sodium (Na) and Chlorine (Cl)
Such orderly arrangement at the atomic level produces specific shapes
in crystals at the macroscopic level that reflect the atomic structure

31. The structure of minerals depends on:
Size of the ions involved
Electrical charge of the ions involved

32. Crystal Form Reflects the Internal Arrangement of Atoms