Group 2 Flashcards
Explain the trend in atomic radius down G2?
It increases because the distance from the nucleus increases as a new shell forms down the group
Explain the trend in ionisation energy down G2?
IE decreases down the group because the distance from the nucleus, and shielding outweigh the nuclear charge
ie less energy required to remove outer shell electrons
Explain the trend in melting point down G2?
mp. decreases because the distance from the nucleus is larger down the group so there is a weaker force of attraction from the nucleus to delocalised electrons
This means cations cannot attract delocalised electrons and form metallic bonds
What is the exception in the trend of melting point down G2?
Magnesium has the lowest mp.
unknown reason
How can Titanium ores be extracted using a G2 metal?
Magnesium can be used to extract Ti from its common ore, TiO2
What are the equations from the extraction of Ti from TiO2?
- first react TiO2 with C and Cl:
TiO2 + 2C + 2Cl2 -> TiCl4 + 2CO - Then react TiCl4 with Mg:
TiCl4 + 2Mg -> Ti + 2MgCl2
Mg acts as a reducing agent here because it loses electrons
How does the Ti extraction method using Mg, vary to other extraction methods?
It is more complicated because it is a 2 step process.
TiO2 cant just be reacted with C like normal because this would result in a useless, brittle substance
Ti is very strong and has good qualities that make the process worthwhile
How does acid rain form?
SO2 in the atmosphere reacts with O2 to form SO3, this reacts with water from rain clouds and forms sulfuric acid
How can Ca compounds be used to prevent acid rain?
CaO or CaCO3 can be made into a slurry using water. This can be sprayed over the SO2 gas.
CaSO3 (calcium sulfide) formed can be dried and collected
What equations show the use of Ca compounds to prevent acid rain?
CaO(s) + SO2(g) -> CaSO3 (s) (+ H2O)
CaCO3(s) + SO2(g) -> CaSO3(s) + CO2(g)
How does reactivity with water change down group 2?
It increases down G2
This is because ionisation energy decreases so less energy is required to remove the 2 electrons needed for the reaction of alkaline metal and water
How does Beryllium react with water?
NO reaction
How does Mg react with water?
- It reacts slightly with water:
Mg(s) + H2O(l) -> MgOH(aq) + H2(g) - It reacts vigorously with steam:
Mg(S) + H2O(g) -> MgO(s) + H2(g)
Explain the trend of solubility of hydroxides down group 2
Solubility increases down G2
What are the medical uses of magnesium hydroxide?
It is used to combat heartburn by neutralising the excess stomach acids present in the body.
Due to its low solubility it doesnt dissolve and damage to other organs by being absorbed
