Group 1 And 2 Compounds

Question 1

Thermal stability of carbonates and nitrates increases down the group

Answer 1

Carbonate and nitrate ions are large negative ions which can be made unstable by positively charged ions.

This happens by the positively charged ion polarising the negatively charged and creating distortion. Greater distortion, less stable the compound is

Question 2

Thermal stability of group 1 and group 2 compounds

Answer 2

Group 2 are less thermally stable that group 1 compounds

Group 2 positively charged ions have a 2+ charge compared to a 1+ charge

Question 3

Testing for thermal stability of nitrates

Answer 3

How long it takes for certain amount of O2 to be produced —

Question 4

Testing for thermal stability of carbonates

Answer 4

How long it takes for an amount of CO2 to be produced—

Question 5

Flame colours of group 1 elements

Answer 5

Lithium: red 
Sodium : orange 
Potassium: lilac 
Rubidium: red 
Caesium: blue

Question 6

Flame colours of group 2 metals

Answer 6

Calcium: brick red
Strontium: crimson
Barium : green

Question 7

How to carry out flame test

Answer 7

Mix a small amount of compound your testing with with a few drops of hydrochloric acid

Heat a piece of Platnum nichrome wire in a hot Bunsen flame to clean

Dip the wire into compound/acid mixture hold it in a very hot flame and note the colour produced

Question 8

Explanation for flame colours

Answer 8

The energy absorbed from the flame causes electrons to move to a higher energy level

Colours are seen as elections fall back down to low energy levels, releasing energy in the form of light

Difference in energy between higher and lower levels determines the wavelength of the light released. Therefore it determines the colour of the light