Lecture 4.3b

Which group in the periodic table does silicon belong to?

• Group IV

• Group III

• Group V

• Group VI

What is the oxidation number of silicon?

• +2

• +3

• +4

• +5

Where are complex silicates found?

• In the atmosphere

• In the oceans

• In rocks, clays, and soils

• In living organisms

How is the silicate tetrahedra structure made stable?

• By sharing electrons to form covalent bonds between Si and O

• By accepting electrons to form ionic bonds from other atoms

• By a combination of sharing and accepting electrons

• All of the above

Which type of bonds are formed between Si and O in silicate tetrahedra?

• Ionic bonds

• Covalent bonds

• Metallic bonds

• Hydrogen bonds

Silicates can consist of individual SiO₄ tetrahedra or these linked in which of the following forms?

• Chains, rings, sheets, or as a 3D covalent network

• Only chains

• Only rings

• Only sheets

What is the purpose of positive ions in silicates?

• To balance the negative charge

• To increase the weight

• To decrease the melting point

• To enhance the color

When transition elements are present in silicates, what is the usual effect on the mineral?

• The mineral is usually colored

• The mineral becomes transparent

• The mineral becomes brittle

• The mineral loses its luster

What element is substituted for some of the silicon atoms in the silicate structure in aluminosilicates?

• Magnesium

• Aluminium

• Iron

• Calcium

What is the ratio of (Al+Si):O in aluminosilicates compared to the parent silicate?

• It is higher

• It is lower

• It is the same

• It varies