Group 2 Model Answers Flashcards
State the trend in atomic radius down group 2 and the reason why
Increases
More electron shells
State and explain the trend in melting points of the group 2 metals
Decreases
Metallic bonds weaker OR weaker attraction between ions and delocalised electrons
Ions larger
Uses of BaSO4
Barium meal OR
Test for sulfate ions
Why can magnesium hydroxide not be used in a titration?
Magnesium hydroxide is insoluble/insufficiently soluble/sparingly soluble/forms low concentration solutions
State and explain the trend in the first ionisation energy going down Group 2
Decreases
Down the group the atomic radius increases OR electron removed is further from the nucleus
Shielding increases
Less energy needed to remove an electron
Why does calcium have greater melting point than strontium?
For Ca delocalised electrons closer to cations/positive ions/atoms/nucleus
Ca has stronger attraction between the cations/positive ions/atoms/nucleus and delocalised electrons OR stronger metallic bonding
Give a medical use for magnesium hydroxide
Used as antacid/relieve indigestion/neutralise stomach acidity
State and explain the trend in the first ionisation energies down group 2
Decrease
Ions get bigger/more energy shells
Weaker attraction of ion to lost electron
Calcium flame colour
Brick red
Strontium flame colour
Red
Barium flame colour
Pale green
Test for Mg2+
Add NaOH
White précipitâte
State and explain which block of the periodic table the Group 2 elements belong to.
s-block
outer electron is in s-orbital
test for NH4(+)
Add aqueous NaOH
Warm gently
Test gas produced with red litmus paper
If litmus changes from red to blue ammonia gas is produced
Equation for formation of NH3
NH4(+) + OH(-) -> NH3 + H2O
