U1.C Bonding and Structure

Question 1

Monatomic
Gases

Answer 1

These are the noble gases,
helium, neon and argon.

They are unreactive and exist as single atoms held together only by weak Van der Waals forces.

Low density, melting point and no conductivity.

Question 2

Covalent
Molecular
Gases

Answer 2

H, N, O, F, Cl all exist as diatomic elements (H2, N2 etc) and are gas as room temperature.

Atoms are
held to each other by strong
covalent bonds, but molecules held
together by weak intermolecular forces.

Low density, melting point and no conductivity.

Question 3

Covalent
Molecular
Solids

Answer 3

Phosphorus, sulfur and
carbon (fullerene) exist as
molecules but larger than
diatomic: P4, S8, C60.

All are solid at room
temperature, but will still
have relatively points.

Question 4

Covalent
networks

Answer 4

Large, rigid 3D lattice held
together by strong covalent
bonds.

Boron silicon and carbon form covalent networks.

High melting because only
contain strong bonds.
e.g. diamonds and graphite

Question 5

Metallics

Answer 5

Li, Be, Na, Mg, Al, K, Ca

Outer electrons are delocalised (free to
move). This produces an electrostatic force of attraction between positive metal ions and negative delocalised electrons.

Delocalised sea of electrons is
responsible for the conductivity of electricity.

High melting and boiling points.