Group 2 Flashcards
What is the trend in atomic radius going down group 2 and why?
Atomic radius increases down group 2 because of the additional electrons in each shell
What is the trend in ionic radius going down group 2 and why?
Ionic radius increases down group 2 because when removing the outer shell electrons, the electrons are now in fewer shells.
What is the trend in reactivity going down group 2 and why?
Reactivity increases down group 2 because shielding increases down the group which means that it becomes easier to lose the outer electron
What is the trend in first ionisation energy going down group 2 and why?
The first IE decreases down group 2 because the increase in shielding outweighs the increase in nuclear charge which means it is easier to remove the electron from the outer shell.
Describe the structure group 2 elements have.
Metallic structure, the positive metal ions are attracted to the negative sea of delocalised electrons
What is the trend in melting point going down group 2 and why? Which element is the exception to this?
The melting point decreases down group 2 because as you go down the group, distance from the nucleus to the outer electrons increases which means there is a weaker electrostatic
force of attraction which is easier to overcome hence low MP and BP. Magnesium is the exception.
Why does boiling point give a better idea of the strength of a metallic bond rather than the melting point?
Boiling point gives a better idea of the strength of a metallic bond because it involves completely breaking the metallic bonds. Melting point only involves the partial breaking of metallic bonds.
Explain the trend in reactivity with water going down group 2 and why.
Reactivity increases since the outer electrons are easier to remove due to increased shielding.
Explain the reaction of Mg with water.
Metal + Water -> Metal hydroxide + Hydrogen
- Magnesium reacts very slowly with water because it is very unreactive. Only a small bubble of hydrogen gas and Mg(OH)2 would be produced.
- Mg(OH)2 is sparingly soluble.
- Magnesium reacts faster with steam forming MgO because hydroxide is not stable enough at a higher temperature and is burned with a bright white light to produce MgO + H2
Water:
Mg + H2O -> Mg(OH)2 + H2
Steam:
Mg + H2O -> MgO + H2
What is solubility?
An element or compound disassociating into its ions.
What is the trend in the solubility of the group 2 hydroxides going down the group?
Solubility increases down the group.
What is the trend in solubility of group 2 sulphates going down the group and why?
The solubility of group 2 sulphates decreases down the group because the cation gets larger so it has a lower charge density therefore is becomes less attracted to the polar water molecule.
What is the trend in basic strength of group 2 hydroxides going down the group and why?
Basic strength increases down group 2 because solubility increases which means the concentration of OH- ions increase which increases the pH.
Why does Ba(OH)2 have a more basic pH than Mg(OH)2?
Because Ba(OH)2 is more soluble which means it has more OH- ions.
What can calcium hydroxide Ca(OH)2 be used for and its equation.
It can be used in agriculture to neutralise acid soils.
Ca(OH)2 + 2H+ -> Ca2+ + 2H2O
