From Atoms To Minerals Flashcards
Protons
Have positive charge and their number in the nucleus defines an element
What is an atom
A basic unit of matter that consists of a central nucleus surrounded by a cloud of electrons
- nucleus
- protons
- neutrons
- electron orbital shells
Neutrons
Are electrically neutral but a large number of them can make nucleus unstable so it decays radioactively
Electrons
Have negative charge, they can be shared with neighboring atoms to produce bonds
What is an element
An atom of a given element has specific properties that can differentiate its behavior in nature from atoms of other elements
-an element is defined by the number of protons in the nucleus of its atoms
Bohr’s model of an atom
- electrons orbit nucleus in discreet energy shells and sub-shells
- addition of electrons into a new shell defines a new row in periodic table
- atom favors an even amount of electrons, Na gives away an electron to become + charged cation, Cl gains an electron to become - charged anion
Ions and valence
- ion is charged atom
- valence is the charge that an atom has when bonded
- for example: silicon is always +4 in minerals
- for example: oxygen is always -2 in minerals
- some elements can have variable valance, for example: Fe^3+ and Fe^2+
Ionic bonding
Electron almost completely “moves” from an atom to its neighboring atom as in NaCl
Covalent bonding
Electrons are shared by two atoms as in O^2
Metallic bonding
Electrons hop from one atom to the next as in Cu metal
Anionic groups
Sometimes in nature, different elements tend to be strongly bonded together to form an Anionic group
- SiO4^4-
- SO4^2-
- CO3^2-
Minerals
A mineral is a naturally occurring inorganic solid, with a regular internal crystal structure, formed by inorganic or organic processes
Polymorphs
Different minerals, that have different structure, that have the same chemical composition
-polymorphs reflect different temperature and/or pressure conditions of crystallization
Major environmentally important mineral groups
- mineral groups are defined on the basis of the principal anion or Anionic group, except for the native element group
- each mineral group tends to have a distinct genesis, behavior, and use
Native elements
Diamond C, Graphite C, Copper Cu, Gold Au, Silver Ag
-some uses: jewelry, electrical conductors, insulators, abrasives
Halides
- anions are halogens, including F-, Cl-
- examples: halite NaCl, sylvite KCl, fluorite CaF2
- some uses: salts, electronics, chemical industry, precipitate in salty water
Oxides
- anion is oxygen (O^2-)
- examples: hematite Fe3O4, rutile TiO2
- some uses: metallurgy, electronics, pigments, ceramics
Hydroxides
- Anionic group is hydroxyl (OH-)
- examples: geothite FeOOH, gibbsite Al(OH)3
- clays are hydroxides
- some uses: gibbsite is a major source for aluminum, ceramics
Sulfides (S2-)
- anion is sulfur S2-
- examples: pyrite FeS2, Galena PbS
- commonly make ores of important metals, including copper lead and zinc
Sulfates
Anionic group is sulfate SO4^2
- examples: gypsum CaSO4H2O, barite BaSO4
- include mostly alkali earth elements bonded with sulfate
- usually form evaporates by evaporation of salty water
Carbonates
Anionic group is carbonate CO3^2-
- examples: calcite CaCO3, dolomite MgCa(CO3)2
- precipitate in warm ocean water
- important in the carbon cycle
- most caves occur in carbonates
- some uses: building industry chemical industry
Phosphates
Anionic group is phosphate PO4^3-
Example: apatite Ca5(PO4)3(OH,F)
-bones are biogenetic phosphates
-some uses: fertilizers
Silicates
Anionic group is silicate (SiO4^4-)
- examples: Quartz SiO2
- some uses: glass, ceramics, electronics, abrasives, food
Silica tetrahedron
The basic building block of silicates
-can be stacked in several different arrangements with other cations in between
