Group 2 and writing balanced equations - Chemical Ideas 1.2, 3.1 and 11.2
Writing the formulae you will need
These are two lists of useful formulas the one on the left contains some basic compounds and the ion formulae on the right show charged ions
These are two lists of useful formulas the one on the left contains some basic compounds and the ion formulae on the right show charged ions
Example 1
What is the formula of Magnesium chloride?
1 x Mg 2+ is balanced by 2 x Cl -
Formula = MgCl2
Example 2
What is the formula of Calium Hydroxide?
1 x Mg 2+ is balanced by 2 x OH -
Formula = Mg(OH)2
Balancing equations
There are four steps in order to be able to balance an equation
Step 1 - Write the word equation
Step 2 - Put in the formulae
Step 3 - Balance the equation
Step 4 - Add state symbols (this is not a required step unless you are asked to give state symbols)
Reactions of the elements in group 2
The metals react with water to give metal hydroxide and hydroge. As you go down the group reactants react more vigorously.
The oxides react with acid in order to act as bases. This then spends up other reactions.
The oxides react with water to give an alkaline solution of the hydroxide.
Hydroxides react with acid to produce salt and water. Solublity of element increases as you go down a group.
When carbonates are heated they undergo thermal decomposition and give off the metal oxide and carbon dioxide. Solublity of element decreases as you go down a group and thermal stability increases. This means group 2 elements in periods 1 and 2 will more likely break down on heating thsn in period 3 and 4
What is the formula of Magnesium chloride?
1 x Mg 2+ is balanced by 2 x Cl -
Formula = MgCl2
Example 2
What is the formula of Calium Hydroxide?
1 x Mg 2+ is balanced by 2 x OH -
Formula = Mg(OH)2
Balancing equations
There are four steps in order to be able to balance an equation
Step 1 - Write the word equation
Step 2 - Put in the formulae
Step 3 - Balance the equation
Step 4 - Add state symbols (this is not a required step unless you are asked to give state symbols)
Reactions of the elements in group 2
The metals react with water to give metal hydroxide and hydroge. As you go down the group reactants react more vigorously.
The oxides react with acid in order to act as bases. This then spends up other reactions.
The oxides react with water to give an alkaline solution of the hydroxide.
Hydroxides react with acid to produce salt and water. Solublity of element increases as you go down a group.
When carbonates are heated they undergo thermal decomposition and give off the metal oxide and carbon dioxide. Solublity of element decreases as you go down a group and thermal stability increases. This means group 2 elements in periods 1 and 2 will more likely break down on heating thsn in period 3 and 4