CHAPTER 8 - REACTIVITY TRENDS Flashcards
What are group 2 metals also known as?
Alkaline earth metals
What are group 2 metals found as?
Stable compounds like calcium carbonate (do not occur in their elemental form naturally)
What is the most common type of reaction in group 2 elements?
Redox reactions
What happens to a group 2 metal when it is in a redox reaction?
It loses two electrons to form a 2+ ion and it’s oxidised
Why are group 2 elements called reducing agents?
Because they reduce another species
What happens when magnesium is reacted with oxygen?
magnesium will burn with a bright white light and white magnesium oxide is formed
What are the products of a reaction between a group 2 metal and oxygen?
A metal oxide (e.g MgO)
What is formed when group 2 elements react with water?
An alkaline hydroxide (e.g. Mg(OH)2) and Hydrogen gas (H2)
Why do reactions between group 2 elements and water become more vigorous down the group?
Reactivity increases down the group
Metal + acid —> ___________+___________
Salt + hydrogen
Explain the trend in ionisation energy down group 2.
- ionisation energy decreases down the group
- increasing atomic radius and increasing shielding
- nuclear attraction between nucleus and outer electrons decrease so it’s easier to remove outer electron
What happens when group 2 oxides (e.g. MgO) react with water?
A metal hydroxide is formed (e.g. Mg(OH)2) and hydroxide IONS are released
What happens to the solubility of group 2 hydroxides in water down the group?
- solubility increases
- pH increases
- alkalinity increases (as there will be more OH- ions in the resulting solution)
How and why is calcium hydroxide used in agriculture?
- added to fields by lime farmers
- increase pH of soil and neutralises acid in soil to form neutral water
How and why are group 2 compounds used in medicine?
- group 2 bases used as antiacids for treating acid indigestion
- magnesium hydroxide and calcium carbonate used to neutralise HCl in stomach
