Topic 4 - INORGANICS Flashcards
Why does ionisation energy decrease down group 2?
- Outer electron is in a successively higher energy level
- Distance and shielding both increase
- (Even though nuclear charge increases)
- Attraction between outer electron and nucleus is weaker
What is the trend in reactivity down group 2?
‘Reducing strength’ increases down group 2
- The sum of 1st and 2nd ionisation energies decreases
- The strength of metallic bonding decreases
What is the trend in hydroxide solubility down group 2?
Group 2 hydroxides become more soluble down the group
What is the trend in sulphate solubility down group 2?
Group 2 sulphates become less soluble down the group
Group 2 metal + oxygen –> ?
Group 2 metal oxide
Are group 2 elements oxidised or reduced when reacted with something?
Always oxidised
- They gain a 2+ charge
What are the properties of a group 2 metal oxide?
- Ionic compound
- White solid
- High melting point
Group 2 metal + chlorine –> ?
Group 2 metal chloride
What are the properties of a group 2 metal chloride?
- Ionic compound
- White solid
- High melting point
Group 2 metal + water –> ?
Group 2 metal hydroxide + hydrogen
What are the observations of a reaction between a group 2 metal and water?
- Effervescence
- Metal disappears
- Delayed white precipitate with Ca(OH)2
Group 2 metal oxide + water –> ?
Group 2 metal hydroxide
What are the observations of a reaction between a group 2 metal oxide and water?
White precipitate formed with Mg(OH)2 and Ca(OH)2
Group 2 metal oxide + acid –> ?
Salt + water
Why does CaCO3 thermally decompose?
- Ca2+ ion polarises the CO3 2- ion
- The lower electron density at the other end of the CO3 2- ion weakens a C-O bond
- When provided with heat, the bond breaks
Why do nitrates thermally decompose?
- The cation polarises the NO3- ion
- The lower electron density at the other end of the NO3- ion weakens an N-O bond
- When provided with heat the bond breaks
Are group 1/2 carbonates/nitrates more or less thermally stable down the group?
More stable
Why are group 1/2 carbonates + nitrates more thermally stable down the group?
- Cation radius increases
- Cation polarises CO3 2-/NO3- less
- C-O/N-O bonds are weakened less
- Either they break more slowly, or they need a higher temperature to break
What are the observations of group 1/2 carbonate decomposition?
- Limewater turns cloudy
What are the observations of group 1/2 nitrate decomposition?
- Glowing splint relights
- Brown fumes
What is the trend of melting/boiling point down group 7?
Melting/boiling point increases down the group