Inorganic chemistry Flashcards
Why ionisation energy decreases down group 2
- more electron shielding
- larger atomic radius
- less attraction between nucleus and outer shell
Why reactivity increases down group 2
- metals lose electrons in reactions
- shielding and atomic radius increase
- it becomes easier to lose electrons
Group 2 reaction with oxygen
Group 2 + oxygen»_space; group 2 oxide
Group 2 reaction with chlorine
Group 2 + chlorine»_space; group 2 chloride
Group 2 reaction with water
Group 2 + water»_space; group 2 hydroxide + hydrogen
Group 2 oxide reaction with water
Group 2 oxide + water»_space; group 2 hydroxide
Group 2 oxide / hydroxide reaction with dilute acid
Group 2 oxide / hydroxide + acid»_space; group 2 salt + water
Solubility of group 2 sulfates down the group
Decreases (remember insoluble barium sulfate precipitate from the test for sulfates)
Solubility of group 2 hydroxides down the group
Increases (magnesium hydroxide can be used as medicine because of its low solubility)
Explain the trend in thermal stability of metal carbonates and nitrates
- thermal stability decreases as polarising power of the cation increases (size decrease, charge increase)
- as the anion’s electrons are distorted, its covalent bonds become weaker
How flame tests work
- electrons absorb energy from the flame
- they move into a higher energy level
- as they move back down, they release the energy as specific wavelengths of light
How to do a flame test
- dip nichrome wire into concentrated HCl then into the solid sample
- hold the wire over a flame and observe the colour
How to test thermal stability of nitrates
- heat the nitrate
- normal decomposition gives no observation
- greater decomposition (so a less stable nitrate) produces brown fumes (nitrogen dioxide)
How to test thermal stability of carbonates
- weigh the sample of carbonate
- heat it
- weigh the sample again
- if mass decreased, decomposition occurred (so a less stable carbonate)
Lithium flame
Red
Sodium flame
Yellow
Potassium flame
Lilac
Rubidium flame
Purple