Periodicity

Question 0

What is the least electronegative element?

Answer 0

Francium (0.7)

Question 1

What is electronegativity?

Answer 1

A measure of the ability of an atom in a covalent bond to attract the electron bond pair

Question 2

Why does electronegativity increase across a period?

Answer 2

Nuclear charge increased while radius decreases

Question 3

Why does electronegativity decrease down any group?

Answer 3

As each element has an extra shell of electrons and a greater radius
Thus, less attraction for outer shell electrons

Question 4

What is ionisation energy?

Answer 4

The energy needed to remove one mole of electrons from one mole of atoms or molecules in gaseous phase

Question 5

How reactive is an element with the low IE?

Answer 5

Very reactive as it is easier to remove an electron

Question 6

Generally ionisation energy increases across a period- why?

Answer 6

Nuclear charge increases with each added proton, while with little extra shielding.
Atomic radius decreases so more energy is needed to remove each electron

Question 7

What are the anomalies of ionisation energy trends?

Answer 7

Group 2 to group 3 decreases as there is shielding by full s subshell
Be/B Mg/Al

N to O decrease as N has a half filled p subshell whereas O has slight e- pair repulsion = O’s electrons are lost more easily

Question 8

Why does Aluminium have a higher melting point than other metals?

Answer 8

It has 3 delocalised electrons, therefore stronger attractions and smaller atomic cores

Question 9

Describe the solubility of group 1 compounds

Answer 9

All are soluble

Question 10

Is Mg(OH)2 soluble or insoluble?

Answer 10

Insoluble

Question 11

How soluble is MgSO4?

Answer 11

Soluble

Question 12

Are group 2 carbonates soluble?

Answer 12

No, all insoluble.

Question 13

Is BaSO4 soluble?

Answer 13

No, insoluble

Question 14

Give 2 balanced equations to show the amphoteric nature of Al2O3

Answer 14

With an acid
Al2O3 + 3H2SO4 -> 2Al2(SO4)3 + 3H2O

With a base
Al2O3 + 3H2O + 2NaOH -> 2NaAl(OH)4

Question 15

Is Al2O3 soluble or insoluble?

Answer 15

Insoluble so doesn’t affect pH of water

Question 16

What is the formula for Berylliumhydroxide?

Answer 16

Be(OH)2

Question 17

What is the bonding in Be(OH)2 and why?

Answer 17

Ionic
High electronegativity
High charge density in Be2+ ion high polarises the anion- so has a covalent character in salts

Question 18

Give two equations to show the amphoteric nature of Be(OH)2

Answer 18

With acid-
Be(OH)2 + 2HCl -> BeCl2 +2H2O
With base-
Be(OH)2 + NaOH -> Na2Be(OH)4

Question 19

What elements show amphoteric behaviour?

Answer 19

Zn, Be, Al, Sn and Pb

Question 20

What type of chloride reacts with water?

Give an example (with balanced eqn)

Answer 20

Covalent chlorides

PCl5 + H2O -> HCl + H3PO4

Question 21

How do PCl3 and PCl5’s reaction with water differ?

Answer 21

PCl3 produces HCl and H3PO3

PCl5 produces HCl and H3PO4