Group 2 Flashcards
What is the trend in group 2 atomic radius and why?
Atomic radius increases because a full energy level of electrons is added between each element
What is the trend in group 2 first ionisation energies?
First I.E. decreases because:- All outer electrons in a full s orbital- Shielding increases - Effective nuclear charge on the nucleus decreases- Weaker attraction to outer electrons- Therefore less energy required to remove the outer electron
What is the trend in group 2 melting/boiling point?
Melting and boiling points decrease because:- All group 2 elements form 2+ ions in metallic structure- Increased shielding causes weaker effective nuclear charge- Decreases strength of electrostatic attractions with delocalised electrons- Therefore less energy needed to overcome the electrostatic attractions
How does reactivity change down group 2?
Reactivity increases ( linked to 1st + 2nd I.E.)
What type of reaction is the reaction of a group 2 metal and water?
Redox reactions
What is formed when a group 2 metal reacts with 2 water molecules?
A metal hydroxide (base) and hydrogen
What temperature water do group 2 metals react with?
Cold water
What forms when Mg reacts with water and why?
A white precipitate because the metal hydroxide is not soluble
What is formed When Ba reacts with water and why?
No precipitate because the metal hydroxide is soluble
What can be said about the reaction of Mg with water?
It is incredibly slow because Mg is the least reactive
How can the reaction of Mg and water be sped up?
React Mg with steam to form magnesium oxide and hydrogen
What is MgO?
An insoluble base
How does solubility change down group 2?
Solubility increases
What is barium hydroxide classed as and why?
A strong alkali because it is very soluble
What is the trend in solubility for the group 2 hydroxides going down a group?
Solubility increases down group 2
What is the trend in solubility for the group 2 sulfates going down a group?
Solubility decreases down group 2
What is the trend in solubility for the group 2 carbonates going down a group?
They are all insoluble
How can you test if you have a group 2 ion present?
Add sodium carbonate, a white precipitate will form for all group 2 ions as they are all insoluble
How can you test for a barium ion in solution?
Add a sulfate ion because a thick white precipitate will form if the barium ion is present because it is insoluble
How can you test for a magnesium ion in solution?
Add sodium hydroxide, if a magnesium ion is present a white precipitate will form because it is insoluble
What are the two uses of magnesium?
- Mg (l) used in the extraction of titanium from its ore- Magnesium hydroxide used as an antacid
What are the two uses of calcium?
- Calcium hydroxide used in agriculture to increase soil pH (neutralise)- Calcium oxide/Calcium carbonate used to remove sulpher dioxide from flue gases
What are the two uses of barium?
Barium sulfate used in medicine (barium meal) because it is highly insoluble so outlines the digestive tract for x-ray viewing
How is magnesium used to extract titanium from its ore?
2Mg(l) + TiCl4(g) -> Ti(l) + 2MgCl2- 1000 degrees c- Argon atmosphere so neither the Mg or the Ti react with oxygen
How is magnesium used as an antacid?
Magnesium hydroxide + 2HCl -> Magnesium chloride + 2H2O
How is calcium hydroxide used in agriculture to neutralise soil?
Calcium hydroxide + acid -> Ca(salt) + water
Why is it preferable to use CaO to remove sulpher dioxide?
CaO + SO2 produces calcium sulfite only. Whereas calcium carbonate produces calcium sulfite and carbon dioxide
