C09 Group 2 Elements

Does atomic radius increase or decrease down group 2?

increase

Why does atomic radius increase down group 2?

atoms have an extra filled level of electrons

Does ionisation energy increase or decrease down group 2?

decrease

Why does ionisation energy decrease down group 2?

atoms have an extra filled level, so electrons are further from the nucleus, so there is more shielding, so electrons are removed more easily

Does melting/boiling point increase or decrease down group 2 except for one anomaly?

decrease

Which element of group 2 is the anomaly in terms of melting/boiling point?

magnesium

Why does the melting/boiling point decrease down group 2?

electrons in the sea of delocalised electrons are further away from ion nuclei, so metallic bond strength decreases, so less energy is required to break the bonds

What is the general reaction of a group 2 metal and water, using M to represent any group 2 metal?

M + 2H₂O → M(OH)₂ + H₂

metal + water →?

metal hydroxide + hydrogen

metal + steam → ?

metal oxide + hydrogen

Does reactivity with water increase or decrease down group 2?

increase

Why does reactivity with water increase down group 2?

the group 2 metal is oxidised, so loses electrons, and outer shell gets further from the nucleus, so there is more shielding and nuclear attraction is weaker

Which group 2 metal is used to extract titanium?

Mg

metal oxide + carbon → ?

metal + carbon dioxide

What is the first step in extraction of titanium from ore?

titanium oxide is reacted with chlorine and carbon to form titanium chloride and carbon monoxide

What is the second step in extraction of titanium from ore?

titanium chloride is reduced to titanium by magnesium

What is the equation for magnesium extracting titanium?

TiCl₄ + 2Mg → 2MgCl₂ + Ti

Does the solubility of group 2 metal hydroxides increase or decrease down the group?

increase

What is magnesium hydroxide used for?

neutralising excess stomach acid

How soluble is magnesium hydroxide?

almost insoluble

What is calcium hydroxide used for?

neutralising acidic soil

How soluble is calcium hydroxide?

sparingly soluble

Does the solubility of group 2 metal sulfates increase or decrease down the group?

decrease

How soluble is barium sulfate?

insoluble

What is barium sulfate used for in medicine?

as barium meals to make soft tissue visible on x-rays

What test is the insolubility of barium sulfate used in?

sulfate ions

What is the first step in a sulfate ion test?

add nitric or hydrochloric acid

What is the next step in a sulfate ion test after adding nitric or hydrochloric acid?

add barium chloride

What is a positive result in a test for sulfate ions?

white precipitate

What is the white precipitate in the test for sulfate ions?

barium sulfate

What are calcium oxide and calcium carbonate used for?

removing sulfur dioxide from flue gases

What is the by-product of using calcium oxide and calcium carbonate to remove sulfur dioxide from flue gases?

calcium sulfite

What is used to remove sulfur dioxide from flue gases?

calcium oxide and calcium carbonate

What is used to neutralise acidic soil?

calcium hydroxide

What is used to make soft tissues more visible on x-rays?

barium sulfate

What is used to neutralise excess stomach acid?

magnesium hydroxide