Covalent Bonding

Question 1

Definition?

Answer 1

The electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms

Question 2

Common covalent substances?

Answer 2

Non-metal elements
Non-metal compounds
Polyatomic ions

Question 3

Dative covalent bond?

Answer 3

Where only one of the bonded atoms donates both electrons being shared

Question 4

Double covalent bonds?

Answer 4

2 shared pairs of electrons

Question 5

Triple covalent bonds?

Answer 5

3 shared pairs of electrons

Question 6

Sigma bonds?

Answer 6

The direct overlap of orbitals in the middle of the 2 bonding atoms donates both

Question 7

Pi bonds?

Answer 7

The sideways overlap of 2 p orbitals resulting in electron density above and below the bond axis which restricts rotation around the bond

Question 8

Graphite?

Answer 8

Each carbon is covalently bonded to 3 other carbons in a hexagonal arrangement in layers
High melting point as covalent bonds need a large amount of energy to break
Each carbon atom has 4 electrons available for bonding but only uses 3 to form covalent bonds
A remaining electron is delocalised- graphite conducts electricity
Insoluble in water- no interactions with water molecules

Question 9

Diamond?

Answer 9

Each carbon atom is covalently bonded to 4 other carbons atoms in a tetrahedral arrangement
Strong covalent bonds therefore a very high melting point
No mobile charge carriers- can’t conduct electricity
Insoluble in water- no interactions

Question 10

What are the 2 types of covalent substance?

Answer 10

Simple covalent (molecular)
Giant covalent (macromolecular)

Question 11

What is the definition of a molecule?

Answer 11

A neutral group of atoms joined by covalent bonds

Question 12

Why do molecular solids often sublime?

Answer 12

When a molecular substance is solid, the molecules form a regular lattice of molecules
The lattice is held together by weak IMF so they sublime

Question 13

Properties of molecular substances?

Answer 13

Low melting and boiling points- all IMF are weak and require little energy to overcome
Do not contain mobile charge carriers and cant carry charge
Polar molecules dissolve in polar solvents like water because PD-PD form between solvent and solute molecules
Non-polar molecules can only dissolve in non-polar solvents like cyclohexane because London forces can form between the solvent and the solute molecules