Flashcards in Elements of Group 1 and 2 - Inorganic chemistry Deck (51)
What is the bonding in the group 1 and 2 elements?
What are the reasons for the trend in melting and boiling point and hardness of group 1 and 2 metals?
Metallic radius increases down the group due to the extra electron shells, so the metallic bonding weakens down the group, and so melting, boiling points and hardness all decrease down the group
Why are group 2 metals harder than group 1 metals and have higher melting and boiling points?
Number of valency electrons increases and metallic radius slightly decreases, so the strength of the metallic bonding increases
What are the reasons for the trend in ionisation energies down group 1 and 2?
The increase in nuclear charge is outweighed by the increased distance between the electron being lost and the nucleus, and the increased shielding effect of complete shells of electrons between the electron being lost and the nucleus
What is lithium's flame test colour?
What is sodium's flame test colour?
What is potassium's flame test colour?
What is magnesium's flame test colour?
Why does magnesium's flame test not produce a colour?
The energy emitted has a wavelength outside the visible spectrum
What is calcium's flame test colour?
What is strontium's flame test colour?
What is barium's flame test colour?
What is rubidium's flame test colour?
What is caesium's flame test colour?
What is beryllium's flame test colour?
Why do flame tests work?
Electrons are excited to a higher energy level by the Bunsen burner flame, and as they fall back down to their ground state (they are unstable in the higher energy state), they emit energy in the form of visible light
How should a flame test be carried out?
1) Use a nichrome wire (very unreactive and so cannot give out a flame colour)
2) Dip the wire in concentrated hydrochloric acid (out it in the flame to check if any colour is being produced, keep cleaning it until there isn't one)
3) Grind up any solid that isn't already a powder
4) Dip the wire in the solid'
5) Put the wire into the flame so a colour is produced
What colour does magnesium burn in oxygen?
Intense white light
What colour does calcium burn in oxygen?
Brick red flame
What colour does strontium burn in oxygen?
Dark red flame
What colour does barium burn in oxygen?
Pale green flame
What compound do all group 2 metals form when they react with chlorine?
Beryllium forms a covalent, anhydrous chloride, all others produce ionic chlorides
Beryllium's reaction with water
There is no reaction
Magnesium's reaction with water
Magnesium reacts very slowly with cold water, but burns when heated in steam
Mg (s) + H2O (g) -> MgO (s) + H2 (g)
Calcium, strontium and barium's reactions with water
React rapidly with cold water
Ba (s) + 2H2O (g) -> Ba(OH)2 (aq) + H2 (g)
How does the reactivity of group 2 elements change down the group?
Barium reacting with oxygen
2Ba (s) + O2 (g) -> 2BaO (s)
Beryllium oxide with water
Magnesium oxide with water
MgO (s) + H2O (l) -> Mg(OH)2 (s)
Reacts slowly and incompletely to form a slightly alkaline suspension of magnesium hydroxide