TOPIC 4: INORGANIC CHEMISTRY & THE PERIODIC TABLE Flashcards
Describe the Trend in ionisation energy of Group 2
As you go down group 2, number of shells increase means increased shielding.There is a lower attraction between the outer electron and nucleus so ionisation energy decreases
Describe the Trend in reactivity down Group 2
The reactivity increases as you go down the group as outer electrons are more easily lost
Equation of GROUP 2 element reacting with water
Metal (solid)+ 2Water (liquid)- Metal Hydroxide (aqueous)+ Hydrogen (gas)
Equation of GROUP 2 element reacting with oxygen
Metal (solid)+ Oxygen (gas) -2Metal Oxide (solid)
Equation of GROUP 2 element reacting with chlorine
Metal (solid)+ Chlorine (gas)- Metal Chloride( solid)
Exceptions on solubility
- Beryllium oxide- does not react with water and beryllium hydroxide isn’t very soluble.
- Magnesium oxide-reacts slowly and magnesium hydroxide is not very soluble.
- Barium sulfate is insoluble
Trends in solubility down Group 2 hydroxides + sulfates
- Singly charged metal hydroxides increase in solubility down the group.
- Doubly charged metal sulfates decrease in solubility down the group.
Equation for metal oxide + water
metal oxide (solid)+ Water (liquid)-Metal hydroxide (aqueous)
Equation for metal hydroxide with water
Metal hydroxide (solid)+Water (liquid)- Metal hydroxide (aqueous)
Equation for metal oxide with dilute hydrochloric acid
Metal oxide (solid)+2 HCL (aqueous)-Metal chloride (aqueous)+ Water (liquid)
Equation for metal hydroxide with dilute hydrochloric acid
Metal hydroxide (aqueous)+ 2HCl (aqueous) - Metal chloride (aqueous)+ 2Water (liquid)
Thermal decomposition
When a substance breaks down when heated
Which ion polarises which ion?
The cation polarises the anion distorting it
Difference in thermal stability between group 1 and group 2 carbonates/nitrates
Group 2 compounds are less stable than group 1 as they have a higher charge density
Relationship between charge density of a cation and thermal stability
The greater the charge density the more the anion is polarised (distorted) the less thermally stable the compound
Thermal decomposition of Group 1 carbonates
Group 1 carbonates do not thermally decompose under a bunsen flame
an exception is lithium carbonate(solid)- Lithium oxide (solid)+ carbon dioxide (gas)
Thermal decomposition of Group 1 nitrates
Group 1 nitrates thermally decompose to form a nitrite and oxygen
General formula: Metal nitrate (solid) - 2Metal nitrite (solid)+ Oxygen (gas)
What is the exception for the thermal decomposition of the Group 1 nitrates
Lithium nitrate(solid)- Lithium oxide (solid)+ Nitrogen oxide (gas)+ Oxygen (gas)
Thermal decomposition of Group 2 carbonates
Group 2 carbonates thermally decompose to form the oxide and carbon dioxide
General formula: Metal carbonate (solid)- Metal oxide (solid)+ Carbon dioxide (gas)
Thermal decomposition of Group 2 nitrates
Group 2 nitrates thermally decompose to form the metal oxide, nitrogen dioxide and oxygen
General formula: 2Metal nitrate (solid)- 2Metal oxide (solid)+ 4Nitrogen dioxide (gas)+ Oxygen (gas)
How to test for carbonates
- See if carbon dioxide is produced
2. Lime water(calcium hydroxide) turns cloudy if carbon dioxide present
How to test for nitrates
- See if oxygen is produced
- If glowing splint is relit oxygen is present
- Nitrogen oxide is a brown gas and is toxic so has to be done in a fume cupboard
Lithium flame colour
red
Sodium flame colour
Orange/yellow
Pottasium flame colour
Lilac
Rubidium flame colour
red
Caesium flame colour
blue
Calcium flame colour
Brick red
Strontium flame colour
Crimson red
Barium flame colour
green
How to do a flame test
- Mix a small amount of the compound with a few drops of hydrochloric acid.
- Heat a nichrome wire in a bunsen flame to sterilise it.
- Dip the wire in the compound and hold it in the hot flame and observe colour produced.
