Group 2 Flashcards
Why don’t some atoms give results in the flame test?
They give out light outside the visible spectrum
The Bunsen burner might not provide enough energy
What is a flame photometer?
This can be used to measure quantitively the wavelengths given out by ions by analysing the flame produced
It’s much more accurate
Why do group 2 metals become harder to ignite as you go down the group?
They form an oxide layer which stops it igniting
What is observed when group 2 metals react with oxygen?
A bright white light
What is the general equation for when group 2 metals react with oxygen?
2M(s) + O2 (g) –> 2MO (s)
What is the general equation for the reaction between group 2 metals and chlorine?
M(s) + Cl2 (g) –> MCl2 (s)
What is the general equation for the reaction between group 2 metals and water?
M(s) +2H20 (l) –> M(OH)2 (aq) + H2
What is the general equation for the reaction between group 2 metal oxides and water?
MO(s) + H2O (l) –> Mg(OH)2 (aq)
What can be observed when group 2 metals react with water?
Turn pH paper alkali
Vigorous effervescence
Magnesium reacts very slowly
Beryllium doesn’t react due to the thick oxide layer
What is the equation for the reaction between magnesium and steam?
Mg(s) + H2O (g) –> H2 (g) + MgO (s)
White solid and bright white light
What can be observed when metal oxides react with water?
Solid remains, showing not completely soluble
Heat
Alkali solution
Solubility increased down the group
What is the general equation for the reaction between group 2 metal oxide and water?
MO(s) + H2O (l) –> Mg(OH)2 (aq)
What causes the colour in the flame test?
Excited electrons emit light when they fall to their ground state
Each element has its own characteristic energy levels
Check markscheme
How does solubility change down group 2 nitrates?
Decreases
What is the general equation for the reaction between group 2 metal oxides and HCl and nitric acid?
MO(s) + 2HCl –> MCl2 (aq) + H2O
MO(s) + 2HNO3 –> M(NO3)2 (aq) + H2O
V
Group 2 salts in which the anion has a charge are largely insoluble
What is the trend in solubility of group 2 sulphates and hydroxides?
Solubility of sulphates decreases down group
Solubility of hydroxides increases
How do you test the thermal decomposition of group 2 carbonates?
Heat carbonate in boiling tube win delivery tube feeding into test tube of limewater
Record time when limewater BEGINS to go cloudy
What is the general equation for the reaction between group 2 metal carbonates decomposing?
MCO3(s) –> MO(s) + CO2(g)
What is the trend in thermal decomposition of the group 2 nitrates?
Become harder to ignite as you go down the group
What is observed when the group two nitrates are heated?
Solid to liquid
Brown gas given off
White solid eventually produced
What is the general equation for the reaction between group 2 metal nitrate decomposing?
M(NO3)2 (s) –> MO(s) + 2NO2 (g) + 1/2 O2
What is the trend in thermal stability of the metal carbonates? Why?
As you go down the group the charge density is reduced
This reduces polarisation/distortion
Of the carbonate electron cloud
Thermal stability of metal carbonates increases down the group
What is the trend of solubility of the sulphates?
The solubility of the sulphate decreases down the group
What is the trend of the solubility of hydroxides in group 2?
As you go down the group the solubility of the hydroxides increases
What are the trends and thermostability of the cabinets and nitrates down group to
Cabinets increase
Nitrates Increase
What Is the trend in electronegativity down group 2?
Decreases
Define the term thermal decomposition
Heat causing the substance to break down into more than one product
What is the general equation for the thermal decomposition of group 1 nitrates?
MNO3 –> NaNO2 + 0.5O2
Why do potassium nitrate in calcium nitrate decomposed form different products?
Calcium ions have a greater positive charge
Therefore they cause greater distortion
Of the anion
