Chapter 10. Group 2

Question 1

Why is Beryllium untypical?

Answer 1

Its ions arevery small with only one shell filled with electrons

Question 2

Note

Answer 2

Reactivity increases down the group.
-Mettallic radius increases down the group
-First + second ionisation energies incraesae up the group
-Density increases down the group
-Reactivity with water to form hydroxides increases down the group
-Sr and Ba also peroxides containing O₂^2- eg Sr + O₂ –> SrO_{2</sub
-Reactions with dilute acids go more vigorous down the group forming a chloride salt and water
-With sulfuric acid, sulfates are formed but descending from Ca the reaction soon stops as the sulfates become increasingly insoluble and coat the metal protecting it from the acid}

Question 3

Note

Answer 3

Group 2 oxides will react with water to form alkaline solutions, the solubility of the hydroxides increases down the group thus Mg hydroxide forms a relatively weak alkaline solution solution
-The oxides and hydroxides will form salts with dilute acids, oxides(water) hydroxides(hydrogen)

Question 4

Note

Answer 4

The carbonates of group 2 metals are insoluble in water
-The carbonates react with dilute sulfuric acid to form a chloride salt and water and carbon dioxide
-The carbonates react with sulfuric acid to form a soluble sulfate for magnesium, insoluble sulfates for the rest of the elemnts and water and carbon dioxide
-The carbonates will decompose to the oxide and carbon dioxide, as we descend the group the carbonates are more stable hence higher temps to decompose
-The nitrates(NO₃) will decompose to form brown nitrogen dioxide gas, the oxide and oxygen gas, the rest is the same as the line above

Question 5

Note

Answer 5

The hydroxides become more soluble down the group and are all white solids
-Group 2 sulfates become less soluble down the group

Question 6

Note

Answer 6

Testing for sulfate ions in a solution
-Acidify the solution with nitric acid or hydrochloric acid(to remove any carbonate ions as barium carbonate is indestinguishable from arium sulfate)
-Add barium chloride
-If sulfate ions are present a white ppt of barium sulfate will form