GROUP 2 - ALKALINE EARTH METALS

Question 1

State and explain the trend in atomic radius going down group 2

Answer 1

-atomic radius increases
-atoms become larger
-number of filled e- shells increases going down the group

Question 2

State and explain the trend in 1st ionisation energy going down group 2

Answer 2

-1st IE decreases going down the group
-atoms get larger
-e- shielding and radius increases
-weaker electrostatic attraction between nucleus and outer e- shell
-easier to remove outer e-

Question 3

State and explain the trend in melting point in group 2

Answer 3

-mp decreases down the group (exception of Mg which is lower than expected
-size of ion increases the distance between nucleus and delocalised e- field increases
-weaker electrostatic attraction
-less energy needed to overcome

Question 4

Describe the bonding in Mg

Answer 4

metallic bonding between Mg2+ ions in a sea of delocalised e-
2de- per Mg

Question 5

Explain why Mg has a high mp

Answer 5

-Metallic bonding between Mg 2+ ions in a giant lattice and a sea of delocalised e-
-strong electrostatic attraction between de- and Mg2+ ions
-a lot of energy required to break bonds

Question 6

State the trend in reactivity of group 2

Question 7

General equation for reaction with water

Answer 7

Metal (s) +2H2O > M(OH)2 + H2

Question 8

How is the reaction of Mg with water different that of Ca, Sr, Br with water

Answer 8

Mg only reacts with steam not liquid water

Question 9

Describe reaction of Mg with steam and write equation

Answer 9

-Bring white flame observed
-producing white solid MgO
Mg(s)+H2O(g)>MgO(s)+H2

Question 10

Explain why very clean Mg will have a slow reaction with water