Giant covalent structures

Allotropes

different forms of the same element with different structures

Giant covalent structure

many atoms joined by covalent bonds forming lattice structures

Diamond

• Each carbon atoms makes 4 single bonds

• regular tetrahedral network= very hard

• no intermolecular forces= high mpt/bpt

• no free electrons= do not conduct electricity

Uses of diamond

Jewelry- hard

coating blades in cutting tools- hard

Graphite

• each carbon atoms forms a single covalent bond with 3 other carbon atoms

• grey-black solid

• arranged in hexagonal layers

• strong covalent bonds- high mpt/bpt

• one free electron can carry charge through structure- conducts electricity

• weak intermolecualr forces between layers so can slide past each other easily- soft and slippery

Uses of graphite

pencils- soft and slippery

industrial lubricant- soft and slippery

Graphene

• one atom thick single layer of graphite

• transparent and flexible

• each carbon atoms forms a single covalent bond with 3 other carbon atoms

• strong covalent bonds- high mpt/bpt

• one free electron can carry charge through structure- conducts electricity

• strong covalent bond- very strong

• one atom thick- light

Uses of graphite

electronic applications; screens and computer chips strength, conductivity, transparency and flexibility

strengthening sports equipment, aircraft wings and cars flexible, strong and light

Buckminster fullerene

• hollow sphere made up of pentagons and hexagons

• each carbon atoms forms a single covalent bond with 3 other carbon atoms

• strong covalent bonds- high mpt/bpt

• one free electron can carry charge through structure- conducts electricity

• strong covalent bond- very strong

• hollow- light

Uses of buckminster fullerene

Target drug delivery hollow structure allows it to form around target molecules and trap it

Catalyst very large SA

Silicon dioxide

• transparent crystals found in sand

• Silicon and oxygen atoms bonded by strong covalent bonds- hard

• no intermolecular forces= high mpt/bpt

• no free electrons= do not conduct electricity

• regular arrangement

Uses of silicon dioxide

Sandpaper

Lining outside furnaces high mpt