Module 3.1.2 - Group 2
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What is another name for group 2 elements?
Alkaline earth metals (all form hydroxides that are alkaline)
What is the electron configuration for group 2 elements?
All end in (shell no.)s2
What block elements are group 2 elements and why?
They are s-block elements - their highest energy orbital occupies an s orbital
What structure do group 2 elements have?
giant, metallic structure
Why are group 2 elements good electrical conductors?
Have mobile delocalised electrons, which can move and carry charge
Why do group 2 elements have a high melting and boiling point?
• a lot of heat energy is required to break the strong metallic bonds
What happens when a group 2 element reacts?
A di-positive ion is formed, as the atom loses two electrons
What do group 2 elements undergo?
Oxidation
What happens to the atomic radii as you go down group 2 elements?
The atomic radii increases down group 2.. - there are more shells, more shielding effect by inner shell electrons - increased distance of outer shell electron and increased shielding effect far outweigh the increase in nuclear charge - nuclear attraction decreases on the outer shell electrons down group 2, so atomic radii increases
What happens to first ionisation energy as you go down group 2 elements?
First Ionisation energy decreases down group 2 as… - atomic radius increases - there are more shells, more shielding effect by inner shell electrons - increased distance of outer shell electrons from nucleus and increased shielding effect far outweigh the increase in nuclear charge - nuclear attraction on outer shell electron decreases - less energy therefore needed to remove an electron from the outer shell of the atom
What happens to reactivity of group 2 elements as you go down?
Reactivity as you go down increases as.. - atomic radius increases - there are more shells, more shielding effect by inner shell electrons - increased distance of outer shell electrons from nucleus and increased shielding effect far outweigh the increase in nuclear charge - weaker nuclear attraction on outer shell electrons - ionisation energy decreases - less energy is needed to remove 2 electrons from the outer shell of group 2 atom, hence reactivity increases
What happens in group 2 elements with oxygen?
• react vigorously with oxygen to produce an oxide (with ionic bonding) • can be burned in air or an atmosphere of pure oxygen
What does a group 2 element and oxygen produce?
[Group 2] metal oxide (solid) redox
What can identify the group 2 element of the metal oxide?
The colour of the flame in which the metal oxide is produced in
What is produce when group 2 elements reacts with water
• redox reaction • react with cold water (room temperature) [Group 2] Metal hydroxide (aq) + Hydrogen gas
What are metal hydroxides?
Weak bases (pH 10-12)
What is seen when group 2 elements react with water?
• solid disappears (dissolves) • Bubbles of gas (fizzing - H2 evolved)
What happens down group 2 when reacting with water?
They react more vigorously down the group
What is the reaction between steam and magnesium?
Mg (s) + H2O (g) -> MgO(s) + H2(g)
What is formed when a group 2 element reacts with an acid?
[Group 2] Metal salt (aq) + hydrogen gas , redox
What is formed when group 2 oxides react with water?
• an alkaline solution of the metal hydroxide, not redox metal oxide + water -> metal hydroxide
What is formed when group 2 hydroxides react with water?
• Group 2 hydroxides dissolve in water to form alkaline solutions • Dissolve into its ions (M 2+, 2OH -)
What happens to the solubility of metal hydroxides down group 2?
Solubility of group 2 metal hydroxides increases down the group
What happens to alkalinity of group 2 hydroxides down the group?
Increases down the group