Chapter 9 (Group 2) Flashcards
What are group 2 elements also known as and why?
Alkaline earth metals because their oxides and hydroxides are alkaline.
How many electrons do they have in their outer shell?
2
Which orbital are the outer electrons in?
s-orbital
How does the radius of the atom change going down the group and why?
The atoms gets bigger as the atomic radius increases as there is an extra outer shell.
How does the melting point change going down the group?
The melting point decreases as the delocalised ‘ sea’ of electrons is further away from the positive nucleus. This means that the strength of the metallic bond decreases and the electrostatic attractive forces between positive ions and delocalised electrons weaken.
How does the ionisation energy change going down the group?
The ionisation energy decreases going down the group as the outer shell of the element become further away from the positive nucleus and the nucleus is shielded by more inner shells of electrons.
Why are all reactions for group 2 oxidation?
The elements lose both the electrons in their outer shell and go from oxidation state of 0 to oxidation state of 2+.
How does the reactivity with water change going down the group and why?
The elements become more reactive going down the group as there is more shielding between the positive nucleus and negative electrons in the outer shell so there is weaker attraction.
How do hydroxides appear?
They are white solids
How does the solubility of hydroxides change down the group?
They become more soluble down the group.
What is the use of barium sulphate?
As barium sulphate is insoluble, it can be ingested to show digestive organs on x-rays.
What is calcium hydroxide also known as and what is its use?
It is limewater and can be used to test for carbon dioxide and to get the correct pH for growing crops.
What is produced when a group 2 metal is reacted with STEAM?
Metal OXIDE and hydrogen
e.g. Mg (s) + H2O (g) > MgO (s) + H2 (g)
What is produced when a group 2 metal is reacted with WATER?
Metal HYDROXIDE and hydrogen
e.g. Mg + 2 H2O > Mg(OH)2 + H2
Which group 2 metal reacts with warm water?
Magnesium