Module 2 - Periodic Table and Crystal Chemistry

Question 1

Silicate Minerals

Answer 1

• dominant igneous rock-forming minerals
• make up most of crust and mantle of earth
• SiO4, strong bond, good for rocks

Question 2

Coordination number

Answer 2

Number of anions around cation

Question 3

Radius Ratio

Answer 3

• Cation radius / Anion radius

Question 4

Silicate Minerals

Answer 4

Dominant igneous rock-forming minerals, make up most of mantle and crust of earth

Question 5

Polymorphous

Answer 5

Crystals of different structure, same chemical composition (allotropes)

Question 6

Isomorphous

Answer 6

• Crystals of the same structure, with different chemical composition

Question 7

Goldschmidt’s Rules

Answer 7

• Two ions with same radius (<15%) will readily substitute for each other
• Two ions with similar radius (15-30%) will sometimes substitute for each other
• Ions whose charges differ by one unit will substitute if electrical neutrality is maintained
• If ions have same charge, Ion with smaller radius is favoured
• If ions have same radius, ion with higher charge is favoured

Question 8

Ringwood’s Rule

Answer 8

No substitution if electronegativity difference is bigger than 0.3