chemistry a level(Group 2 )Watch
1)Name the elements of Group 2 and give the electronic structure using noble gases core notation
2)Explain the link between melting points and atomic radius of group 2
Group 2 should be labelled on your Periodic Table, if not search for one online to refer to. This should help with the first question. The first electron configuration in Noble Gas notation should be [He]2s^2, for Beryllium.
Follow this example for the rest of Group 2. The noble gas used as a shortcut will change each time because you use the one closest in atomic number to your group 2 metal.
Down Group 2, atomic radius increases and melting point decreases. More electrons, so greater distance between positive ion cores in the metallic structure. This increases atomic radius and makes it easier to separate ion cores due to diminished electrostatic forces, so melting point lowers.
1) The noble gas notation is [He] and so your answers are [He]2s1 , [He[2s2] , and so on along the period.
2) As you go down group 2
- Atomic radius increases due to a decreasing attraction between the e- and protons (as the number of shells increase down the group)
- so shielding increases (more e- between the nuclei and outer e-)
- both of which overpower the increase in nuclear charge
- hence less energy is required to overcome the (weak) nuclear attraction, so the melting point decreases down the group.