Periodicity

Question 1

how are elements arranged in the periodic table?

Answer 1

by increasing atomic (proton) number

Question 2

explain the trend in first ionisation energy down a group

Answer 2

• atomic radius increases
• more inner shells so shielding increases
• nuclear attraction on outer electrons decrease
• first ionisation energy decreases

Question 3

explain the general trend in first ionisation energy across Period 2

Answer 3

• nuclear charge increases
• same shell: similar shielding
• nuclear attraction increases
• atomic radius decreases
• first ionisation energy increases

Question 4

comparing the first ionisation energies of Beryllium and Boron

Answer 4

• 2p sub-shell in boron has a more energy than 2s sub-shell in Beryllium
• in boron 2p electron is easier to remove than one of the 2s electrons in beryllium
• 1st I.E. of boron lower than 1st I.E of Beryllium

Question 5

comparing the first ionisation energies of Nitrogen and Oxygen

Answer 5

• highest energy electrons are in a 2p sub-shell
• on O, paired electrons in one of the 2p orbitals repel one another, making it easier to remove an electron from an O atom than N
• 1st I.E of oxygen is less than 1st I.E of N

Question 6

describe the electrical conductivity of metals

Answer 6

• conduct electricity in solids and liquid states

- delocalised electrons can move through the structure

Question 7

describe the melting point and boiling points of metals

Answer 7

• high melting and boiling points

- large amount of energy needed to overcome the strong electrostatic attraction between the cations and electrons

Question 8

describe the solubility of metals

Answer 8

• insoluble

- electrostatic attraction is too strong

Question 9

describe the melting point and boiling points of giant covalent structures

Answer 9

• high melting points and boiling points

- large amounts of energy needed to overcome the strong covalent bond

Question 10

describe the solubility of giant covalent structures

Answer 10

• insoluble

- far too strong to be broken by interaction with solvents

Question 11

describe the electrical conductivity of giant covalent structures

Answer 11

• insulators except graphene and graphite
• in diamond and silicon, no free electrons
• in graphene and graphite, there are free electrons available for conductivity

Question 12

periodicity definition

Answer 12

repeating trends in physical and chemical properties

Question 13

first ionisation energy definition

Answer 13

removal of 1 mol of electrons from 1 mol of gaseous atoms to form 1 mol of gaseous 1+ ions

Question 14

metallic bonding definition

Answer 14

electrostatic attraction between cations and delocalised electrons