Module 3 Chapter 8
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What is another name for the group 2 metals
Alkaline earth metals
What are the properties of the group 2 metals
They are reactive metals and don’t occur naturally in their elemental form. They are usually found in stable compounds —> calcium carbonate Alkaline properties of the metal hydroxides.
How many electrons do group 2 metals have in their outer shells and what sub shell are they in
they have 2 electrons in the outer shell which are in the s subshell
What is the most common reaction that group 2 metals undergo
A redox reaction
What happens to the group 2 metal in a redox reaction and what happens to the electrons
It is oxidised and loses its two outer shell electrons to form a 2+ ions. Another species will gain the electrons and is reduced so it is regarded as a reducing agent.
What is the reaction between a group 2 metal and oxygen
DRAW IT
What substance is oxidised using oxidation numbers in the reaction between a group 2 metal and oxygen
The group 2 metal is oxidised from 0 to +2 Oxygen is reduced from 0 to -2
What is the reaction between a group 2 metal and water
DRAW IT
In the reaction between a group 2 metal and water what is oxidised and what is reduced
The group 2 metal is oxidised as its oxidation number increases from 0 to +2 Hydrogen is reduced as its oxidation number decreases from +1 to 0
What is the reaction between a group two metal and HCL
DRAW IT
In the reaction between a group two metal and HCL what is oxidised and what is reduced
Mg is oxidised as its oxidation number increases from 0 to +2 Hydrogen is reduced as its oxidation number decreases from +1 to 0
What is the reaction between group 2 metal oxides and water
DRAW IT
What is released and as a result what type of solution forms
OH- ions are released forming an alkaline solution and a metal hydroxide.
What do group 2 elements need to do to react
They react by loosing their 2 outer shell electrons. So two successive ionisation energies need to occur.
What is the trend in reactivity as you go down group 2
As you go down group 2 the reactivity increases this is because less energy is required to remove the 2 electrons as you move down the group.
Why does the ionisation energy decrease as you go down the group
Because the attraction between the nucleus and outer shell electrons decreases. Due to increasing atomic radius and increasing electron shielding.
As you go down the group what happens REDOX
They become better reducing agents.
What does solubility do as you go down the group
It increases down the group
Why does solubility increase as you go down the group
The energy needed to separate the ions decreases as there is an increase in the atomic radius and the force of attraction between the delocalised electrons and metal cations in the lattice decreases.
Why does the solubility for the group 2 metal hydroxides increase as you go down the group
The metal - OH bonds become more polar, so more ionic Therefore the ions require less energy to separate As well as this the larger metals can coordinate more water molecules.
What are the group 2 metal hydroxides slightly
They are only slightly soluble in water and if the solution becomes saturated the metal hydroxide will precipitate out into a solid.
As a result of solubility increasing down the group what occurs
There is a greater OH- concentration so as a result it;s more alkaline as you go down the group.
What is the first use of group 2 oxides, hydroxides and carbonates
It is used to neutralise acidic soil in agriculture It is added to fields by farmers as lime to increase the PH of acidic soils.
Example of the neutralisation of soils reaction
Ca(OH)2 + 2H+ —-> Ca 2+ + 2H2O