Part II. How to build a planet (continued) Atoms, Compounds, and minerals:

C. Earth is made of minerals.

1. What is a mineral?

• Physical properties of minerals.
  (Crystal structure and composition are the 2 parameters that determine what mineral forms and control physical properties.)
  • Luster.
  • Cleavage.
  • Crystal faces
  • Hardness.
  • Color
  • Specific gravity (density).
  • Special properties (magnetism, taste, reaction with acid)

D. How to build a crystal.

1. Composition.

a. Atom: the smallest unit of an element. It is hard to imagine, but an individual atom of an element would exhibit the properties of the element.

i. Examples: hydrogen, carbon, iron, aluminum, sulfur, uranium.

ii. More than 106 elements known.

iii. 92 occur naturally on Earth.

iv. Structure:

• Nucleus (protons and neutrons)
  • most of the atom's mass.
  • The number of PROTONS identify/define the element.
  • The number of neutrons determines the isotope of the element.
• Electrons:
  • Found in a cloud around the nucleus.
  • Have almost no mass.
  • The number and their orbital energy determine the chemical characteristics of the atom / element.

Check out this article in National Geographic that shows a recently discovered cave in Mexico that has gypsum crystals up to 36 feet long! Here are some more photos from this cave.

Week 3: Study Questions

Atoms, Compounds, and minerals:

Practice questions:

1. Which of the following determines (or identifies) an element?

• The number of electrons.
• The number of protons and neutrons.
• The number of neutrons.
• The chemical bonds.
• The number of protons.

2. The following are examples of minerals EXCEPT:

• Halite.
• Iron.
• Diamond.
• Gold.
• Coal.

3. Sulfur is a major component of which mineral listed below?

• Quartz.
• Amphibole.
• Micas.
• Diamond.
• Galena.

Answers:

Part II. Atoms, Compounds, and Minerals

1. = The number of protons.
2. = coal.
3. = galena.

In addition to your lecture notes and textbook check out: this web page that has everything you ever wanted to know about your favorite mineral.