Chapter 8 Reactivity Trends Flashcards
Why does reactivity increase down group 2?
Atomic radius and shielding effect increases which decreases ionisation energies
What are the products formed when a group 2 element reacts with water?
Group 2 elements react with water to produce hydroxides
What are the products formed when a group 2 element reacts with oxygen?
Group 2 elements burn in oxygen to form oxides
What are the products formed when a group 2 element reacts with a dilute acid?
Group 2 elements react with dilute acid to produce a salt and hydrogen
What is an example of a group 2 compound in agriculture?
Calcium hydroxide is used in agriculture to neutralise acidic soils
What is an example of group 2 compounds in medicene?
Magnesium hydroxide and calcium carbonate are used in some indigestion tablets as antacids
Why does the halogens boiling point increase down the group?
- More electrons
- Stronger london forces
- More energy required to break the intermolecular forces
- Boiling point increases
Why do the halogens become less reactive down the group
- Atomic radius increases
- More inner shells so shielding increases
- Less nuclear attraction to capture an electron from another species
- Reactivity decreases
Describe the displacement of halogens with halide ions from solution
Halogens displace less reactive halide ions from solution
When these reactions happen, there are colour changes
A halogen will displace a halide from solution if the halide is below it in the periodic table
What is a disproportionation reaction?
A reaction in which the same element is both oxidised and reduced
What are the main benefits of chlorine use?
Chlorine kills bacteria
What are the main risks of chlorine use?
Chlorine reacts with organic hydrocarbons to form chlorinated hydrocarbons which cause cancer
Describe the carbonate test and expected results
1) In a test tube add dilute nitric acid to the solid or solution
2) If you see bubbles the unknown compound could be a carbonate
3) test for CO2 by reacting tyhrough limewater,
4) If limewater turns cloudy then carbonate is present
Describe the sulphate test and expected results
Most sulfates are soluble in water, but barium sulfate is very insolbule, the formation of a white precipitate of barium sulfate is the basis for the test, so react unknown with barium sulphate and look for a white precipitate
Describe the halide test and expected results
1) Add aqueous silver nitrate, to an aqueous solution of the unknown
2) Expect colour change;
White : Chlorine
Cream : Bromine
Yellow : Iodine
3) Add aqueous ammonia to test the solubility of the precipitate
