Giant Covalent and Metallic structure

Question 1

Covalently bonded substances have giant structures

Answer 1

• huge network of covalently bonded atoms
• electrostatic attraction holding atoms together in these structure much stronger than simple covalent
• C + Si form giant networks 4 strong covalent bonds

Question 2

properties of covalent

Answer 2

• high melting points so break a lot of strong bonds before substances melts so takes lots of energy
• extremely hard so strong bonds through lattice arrangement
• good thermal conductors as vibrations travel easily through stiff lattice
• insoluble so covalent bonds means atoms more attracted to neighbours in lattice than to solvent molecules
• cannot conduct electricity since there are no charged ions or free electrons

Question 3

Graphite

Answer 3

• can conduct electricity
• carbon atoms form sheets with each carbon atom sharing 3 of its outer shell electrons with three other carbon atoms
• leaves 4th in each atom fairly free to move between sheets so a good conductor

Question 4

Graphene

Answer 4

• sheet of carbon atoms joined together in hexagons
• 1 atom thick so 2 dimensional compound
• conduct electricity as delocalised electrons free to move so incredibly strong transparent and really light

Question 5

Metals giant structures

Answer 5

• outermost shells electrons delocalised
• positive metal ion
• electrostatically attracted to delocalised negative electrons
• form a lattice closely packed positive ions in a sea of delocalised electrons
• made up of layers of positive metal ions separated by layers of electrons