2.2 - Electrons, bonding and structure

Question 1

Give the number of electrons that can fill the first four shells

Answer 1

2
8
18
32

Question 2

Define an atomic orbital

Answer 2

A region around the nucleus that can hold up to two electrons, with opposite spins

Question 3

Give the shapes of an s and p orbital

Answer 3

S = spherical
P = dumb-bell

Question 4

How many orbitals make up the s, p and d sub-shells?

Answer 4

S = 1
P = 3
D = 5

Question 5

How many electrons can fill s, p and d sub-shells?

Answer 5

S = 2
P = 6
D = 10

Question 6

Define ionic bonding and draw a diagram

Answer 6

Electrostatic attraction between positive and negative ions

Question 7

Why do ionic substances usually exist in the solid state?

Answer 7

Giant ionic lattices have oppositely charged ions strongly attracted in all directions

Question 8

Describe the melting point, solubility and electrical conductivity of ionic compounds

Answer 8

High melting point due to strong electrostatic forces of attraction between oppositely charged ions
Soluble in water as both ionic molecules and water are polar
Can conduct electricity in aqueous state as ions are free to move and carry charge, ions are in fixed position in solids

Question 9

Define covalent bond

Answer 9

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

Question 10

Define average bond enthalpy

Answer 10

A measurement of covalent bond strength

Question 11

Give all the shows of molecules and their bond angles

Question 12

Give the bond angles of common molecules: CH4, NH3, H2O

Answer 12

CH4: 109.5
NH3: 107
H2O: 104.5

Question 13

Define electronegativity

Answer 13

The ability of an atom to attract the bonding electrons in a covalent bond

Question 14

Explain why some molecules have polar bonds but not a permanent dipole

Answer 14

Molecule is symmetrical so polar bonds cancel out

Question 15

What do polar molecules have?

Answer 15

A permanent dipole

Question 16

Name the type of intermolecular bonding

Answer 16

Hydrogen bonding - needs N, O, F and H atom

Question 17

Name the two types of intermolecular forces

Answer 17

Permanent dipole-dipole interactions
Induced dipole-dipole interactions (London forces)

Question 18

Explain the anomalous properties of water resulting from hydrogen bonding

Answer 18

Hydrogen bonds in the open lattice hold the H2O molecules apart whereas in liquid hydrogen bonds break allowing the molecules of water to be closer together
Relatively high melting and boiling point: strong hydrogen bonding between molecules

Question 19

Why are simple molecular lattices solid?

Answer 19

Strong covalent bonds attracted by intermolecular forces between molecules e.g I2, ice

Question 20

Discuss the physical properties of covalent compounds (simple molecular lattices)

Answer 20

High melting point due to strong covalent bonds
Not soluble as no polar bonds
Cannot conduct electricity - no ions