Group 2 and Group 7 Flashcards
Atomic Radius
group 2
Increases. Trend in atomic radius down the group. This trend is due to more orbitals and a weaker nuclear charge as the charge is offset by the shielding that has come about from more orbitals
First ionisation energy group 2
Decreases. Trend in first ionisation energies down the group. This is because the electrons get further from the nucleus so has a weaker pull from the nucleus
Reactivity
group 2
Increases. Trend in reactivity down the group. This is due to the electrons being further from the nucleus allowing the interaction with other molecules
Melting point
group 2
Decreases. Trend in melting point down the group. This is because the delocalised electrons are further from the nucleus as the atomic radius increases
Equation for when an element from group 2 reacts with liquid water:
X + 2H2O -> X(OH)2 + H2
Reactivity with water down group 2
Increases. This is because the ionisation energy decreases so there are more molecules with enough energy for a successful reaction due to increased successful collisions
Trend in solubility of group 2 hydroxides
Increases going down the group.
Trend in solubility of sulphates going down group 2
Decreases
Uses of Mg(OH)2
Treats indigestion
Use of Ca(OH)2
Neutralise Soil
Titanium Extraction Equation
TiCl4 + 2Mg -> Ti + 2MgCl2
How to test for sulphate ions
HCl and BaCl2, look for a white precipitate
Equation for testing for sulphate example
BaCl2 + Na2SO4 -> 2NaCl + BaSO4
Why is acid added to the sulfate/halide ion tests
To remove interfering impurities that can give false positives.
Solubility of BaSO4
Insoluble
Solubility of Mg(OH)2
Sparingly soluble
Define sparingly soluble
Only a very small amount
Use of BaSO4 and why it is safe to use it for this?
Use - X-Rays/Barium meals
This can be safe because barium sulfate is insoluble even though it is toxic.
Uses for CaO and CaCO3
Used to remove acidic gases from chimney flews via wet scrubbing