Group 2 Flashcards
Explain the trend in Atomic Radius down group 2
Atomic Radius gets larger this because extra electron shells are added
Explain the trend in first ionisation energy down group 2
It decreases down the group as each element has an extra electron shell so the nuclear attraction is reduced and there is shielding even though positive charge of nucleus increases but is overridden by shielding
Explain reactivity trend down group 2
It increases as you go down as it is easier to lose an electron as outer electron further away from nucleus
Explain the trend in Melting Point down group 2
Decrease down the group as the metal ions get bigger as you go down but the No. of delocalised electrons doesn’t change so there is a weaker attraction. The dip on magnesium is due to a change in crystal structure
The trend in solubility for hydroxide ions?
Gets more soluble as you go down
The trend in solubility for sulfate ions?
Gets less less soluble as you go down
Explain the test for Sulfate Ions
Barium Sulphate is insoluble so it’s used as a test. First add HCl to neutralise any carbonate ions and then add Barium chloride which will result in a white ppt. of barium sulfate
Give uses of Magnesium and properties
Mg is used to remove titanium from rutile
TiCl4 + 2Mg –> Ti + 2MgCl2
Also used a Milk of magnesia Mg(OH)2 for indigestion as it’s a base so it neutralises stomach acid
Low reactivity, lightweight, durable + strong
Explain the uses of Calcium
It is used in Flue Gas Desulphurisation
Slaked Like - Ca(OH)2 used by farmers to neutralise acid in soil. It is insoluble so it will not dissolve in rain water and contaminate lakes
Calcium Carbonate (limestone) used for indigestion to neutralise acid
2HCl + CaCO3 –> CO2 + H2O + CaCl
Explain the use of Barium
Barium Meals - (BaSO4) - for X rays (Intestines + stomach). It is not soluble, so it’s not absorbed into bloodstream
Explain the trends across Period 3 for:
Atomic Radius
First Ionisation Energy
Melting Points
Atomic Radius slowly decreases a elements in same shell, shielding is same, higher nuclear charge results in electrons being pulled inwards
F.I.E - increases but Al decreases as it moves into a different sub shell so less energy required. Sulphur decreases due to electron repulsion
Melting / Boiling Points
Na/Mg/Al - Metallic
Si - strong covalent bonds require a lot of energy to break
P4/S8/Cl2 - simple molecular
S –> Ar - Van Der Waals forces, weak attraction
increase from Na to Mg then constant to Al then sharp increase to Si then sharp decrease to P then a little increase to S then gradual decrease to Cl then Ar
What is the tests for Ammonium ions
• Add sodium hydroxide
NH4+ + OH- –> NH3 + H2O
• Warm mixture
• Test with- damp red litmus paper, if present, it will turn blue
Explain the trend in electronegativity down group 2?
Slowly decreasing as there is more shielding so the electron is further away making it more difficult to attract it
