III Atoms, Elements and Minerals A Changing scales to looking at the elements of the earth and its crust (8 most common)  B Introduction to minerals that comprise rocks (11 most common)  C The silicate minerals (7)  D Other important rock-forming minerals (4)  E Mineral properties  A Changing Scale: Zooming in from global view to atomic scale Quartz Biotite Feldspar The crust is made of rocks > Rocks are made of minerals > … A Changing Scale: Zooming in from global view to atomic scale Rocks are made of minerals > Minerals are made of atoms Atoms and Elements  Nucleus  Protons    Neutrons     + Charge Has Mass, Atomic # Charge Mass same as One Proton Atomic Mass # Electrons    In shells (2, 8, 8…) - charge (balances each proton +) Very little Mass Electron Shells Ions   Incomplete electron shells tend to be filled E.g Chlorine (Cl-)     17 protons (at.# 17) 17 electrons would make it neutral (no charge) with the last shell one electron short {2, 8, 7} Soooo… Tends to grab an electron to fill the third shell Making it a negatively charged Ion (anion) Ions  Other Common Examples Sodium  Sodium, at.# 11 {2, 8, 1}  Na+ (Cation)  Oxygen, at.# {2,6},  O-2  Silicon, at.# 14 {2,8,4}  Si+4 Oxygen Most Common Elements of Earth’s Crust Oxygen: Silicon: Aluminum: Iron: O-2 Si+4 Al+3 Fe+2 or +3 Calcium: Ca+2 Sodium: Na+1 Potassium: K+1 Magnesium: Mg+2 B Introduction to Minerals  Halite (Rock Salt)     Mineral mined for rock salt and table salt Na gives electron to Cl Opposites attract, elements bond NaCl (Sodium Chloride) * Intro to Minerals    Repeating 3-D pattern forms a Crystalline Solid (or Crystal) Naturally occurring Crystal Form crystals are Minerals Crystalline structure and bonding leads to physical properties: hardness, crystal form, cleavage specific gravity (density) (pg 38-43) planes of cleavage * Silicate Minerals: Examples  E.g., Olivine      * Isolated silicate structure bonded with iron and magnesium Makes up much of the mantle Fe/Mg rich >50% Silica poor