Topic 4 - INORGANICS
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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
Why does melting/boiling point increase down group 7?
• More electrons per halogen molecule • Stronger London forces between molecules • More energy required to overcome IMFs
How does state of matter vary down group 7?
• Fluorine: Gas • Chlorine: Gas • Bromine: Liquid • Iodine: Solid
How does colour change down group 7?
Colour becomes darker down the group Pale yellow->grey