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

region around the nucleus that can hold up to 2 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

Answer 6

electrostatic attraction between + and - 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 MP = strong electrostatic forces of attraction between oppositely charged ions
• soluble in H2O = both ionic molecules and H2O are polar
• can conduct electricity in (aq) = ions free to move and carry charge, whereas in fixed position in solids

Question 9

Define covalent bond

Answer 9

pair of electrons shared between non-metal atoms

Question 10

Define average bond enthalpy

Answer 10

measurement of covalent bond strength

Question 11

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

Answer 11

CH4: 109.5
NH3: 107
H2O: 104.5

Question 12

Define electronegativity

Answer 12

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

Question 13

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

Answer 13

symmetrical molecule so polar bonds cancel out

Question 14

What do polar molecules have?

Answer 14

permanent dipole

Question 15

Name the strongest type of IMF

Answer 15

hydrogen bonding: needs N, O or F, and H

Question 16

Name the 3 types of intermolecular forces

Answer 16

• London forces
• permanent dipole-dipole interactions
• hydrogen bonds

Question 17

State and explain the anomalous properties of ice caused by H bonding

Answer 17

• ice is less dense than water = its molecules are held apart by hydrogen bonds
• relatively high MP/BP = relatively strong H bonds between molecules

Question 18

Why are simple molecular lattices solid?

Answer 18

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

Question 19

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

Answer 19

• high MP = strong covalent bonds
• insoluble = no polar bonds
• cannot conduct electricity = no ions

Question 20

Describe ‘ionic lattice’

Answer 20

• repeating pattern
• of oppositely charged ions

Question 21

Why would one molecule’s LFs be stronger than another’s, leading to a higher BP (if no other types of IMF)?

Answer 21

more electrons = stronger LFs
(NB: when comparing IMFs, always say they are between molecules)

Question 22

Which repel more - lone or bonding pairs?

Answer 22

lone pairs
(include in shape of molecule answer if both types are present)