2.1 Periodicity

Question 1

What is the trend in atomic radius as you move across a period?

Answer 1

It decreases

Question 2

Explain the trend in atomic radius as you move across a period.

Answer 2

As you move across, the charge of the nucleus and number of electrons increase, causing there to be a stronger force of attraction and smaller radius.

Question 3

What is the trend in melting point across a period?

Answer 3

There is an increase as you move along until a sharp peak at group 4, then a decrease as you move along.

Question 4

Why do group 4 elements have such a high melting point?

Answer 4

due to their giant covalent structure (4 covalent bonds)

Question 5

Why does melting point increase as you move along the metals in a period

Answer 5

As the number of valence electrons increase, there are more delocalised electrons in the metallic structure, causing a higher electrostatic attraction, and requiring more energy to break these bonds.

Question 6

define first ionisation energy

Answer 6

The amount of energy to remove one mole of electrons from one mole of a gaseous element.

Question 7

What happens in terms of reactivity as you move down group 2?

Answer 7

They become more reactive as you move down the group as it is easier to remove the outer valence electrons

Question 8

What happens in terms of atomic radii as you move down group 2?

Answer 8

It increases as you move down the group due to increased number of full energy levels as

Question 9

What happens in terms of First ionisation energy as you move down group 2?

Answer 9

it decreases as you move down, as the atomic radius increases (increasing distance from nucleus so requiring less energy) and shielding increases (more complete energy levels between outermost electrons and nucleus)

Question 10

What happens in terms of melting points as you move down group 2?

Answer 10

It decreases as you move down the group as radius of ions increase, charge density decreases, and the force of attraction between metal ions and electrons decreases, reducing strength of metallic bonding.

Question 11

What happens in terms of solubility as you move down group 2 hydroxides?

Answer 11

It increases as you move down the group

Question 12

what happens in terms of solubility as you move down group 2 sulfates?

Answer 12

It decreases as you move down the group

Question 13

What is the general equation for the reaction of group 2 metals with water?

Answer 13

M(s)+2H2O(l)->M(OH)2(aq)+H2(g)

Question 14

What is the reaction of Beryllium and Water like ?

Answer 14

There is no reaction with water or steam, even when heated