periodicity

Question 1

explain how the properties of a metal link to structure & bonding

Answer 1

• giant metallic lattice
• metallic bonding
• lots of energy required to break bonds = high mp/bp
• delocalised electrons free to move = conducts electricity in solution & solid

Question 2

explain how the properties of a non metal link to structure & bonding

Answer 2

• simple molecular
• covalent bonding
• weak induced dipole dipole forces
• require little energy to overcome so low mp/bp
• no mobile charge carriers so do not conduct electricity

Question 3

explain how the properties of an ionic compound link to structure & bonding

Answer 3

• giant ionic lattice
• ionic bonding
• stronger than london forces, require more energy to break so higher mp/bp
• ions in fixed position in solid so cannot conduct electricity
• ions mobile in solution so conduct electricity

Question 4

explain why reactivity increases down group 2

Answer 4

• increasing atomic radius
• with more shielding
• so nuclear attraction is weaker
• ionisation energy decreases
• outer e- lost more easily

Question 5

explain why magnesium has a greater melting point than sodium

Answer 5

• Mg has more outer electrons
• Mg has a larger charge density
• so nuclear attraction is greater

Question 6

explain why phosphorus has a greater melting point than chlorine

Answer 6

• P has more electrons
• so there are greater induced dipole dipole forces
• which require more energy to overcome

Question 7

describe the trend in ionisation energy across a period

Answer 7

• increases
• nuclear charge increases
• similar shielding
• atomic radius slightly decreases due to greater attraction
• more energy required to remove outer e-

Question 8

state and explain the trend in atomic radius across period 2

Answer 8

• decreases
• same shielding
• increased charge
• increased nuclear attraction

Question 9

why do successive ionisation energies increase with ionisation number?

Answer 9

• radius decreases
• so nuclear attraction increases

Question 10

explain why Mg has a greater first ionisation energy than Al

Answer 10

• Mg outer electrons in 3s subshell
• Al outer electrons in 3p subshell
• p subshells has higher energy

Question 11

explain why there is a slight decrease in IE at aluminium & boron

Answer 11

• evidence of subshells
• outer electron sits in higher energy subshell
• which is further from the nucleus

Question 12

explain why there is a slight decrease in IE at sulfur & oxygen

Answer 12

• evidence of electron repulsion
• P&S / N&O have outer electron in 3p orbital
• removing electrons takes it from a 2 electron orbital
• electrons repel so less energy is required to remove the electron with 2 in an orbital than 1 in an orbital