Download Group 1 - down the Group, first ionization energy decreases. As the

Group 1
- down the Group, first ionization energy decreases. As the atomic radius increases and the negatively charged electron is further
from the positively charged nucleus it is less attracted to the nucleus (electron is said to be 'shielded')
- down the Group, second ionization energy decreases. As successive electron 'shells' (energy levels) are filled, the negatively
charged electron is further from the positively charged nucleus and is therefore less attracted to the nucleus.
- second ionization energy is much greater than the first ionization energy for each element. Once an electron has been removed
from the gaseous atom, it forms an ion of charge 1+, this ion then has the electron configuration of a Noble Gas which is extremely
stable, and it is therefore VERY difficult to remove an electron from this arrangement of electrons.
- In general, electronegativities decrease down the Group as successive energy levels (electron shells) are filled resulting in the
positive nucleus exerting less of a force of attraction on electrons
- melting point decreases down the Group as the elements become less metallic in nature
- densities increase down the Group
Group 4:
Appearance
-similarity in appearance between elements in the same Group is much less apparent in Group 14
-considerable change in character on descending the Group
General Reactivity
-elements change from non-metallic in character at the top of the Group to metallic at the bottom
-Carbon is a non-metal, silicon and germanium are metalloids, and tin and lead are typical metals
-general reactivity of the Group as a whole is therefore difficult to ascertain, and the reactivity of each element must be considered
individually
Occurrence and Extraction
-Carbon, tin and lead can all be found in the elemental form in the Earth’s crust, and are readily mined.
-Silicon is found in mineral deposits and purified from them.
Physical Properties
-vary quite widely from one element to another, consistent with the increasing metallic character on descending the Group.
Chemical Properties
-In general, chemical reactivity increases on descending the Group.
Group 7: Trends in Electronegativity
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of
electrons.
As the atoms get bigger, any bonding pair gets further and further away from the
nucleus, and so is less strongly attracted towards it. In other words, as you go down the
Group, the elements become less electronegative.
Trends in Melting Point and Boiling Point
Both melting points and boiling points rise as you go down the Group.
Fluorine and chlorine are gases at room temperature, bromine is a liquid
and iodine a solid.
All of the halogens exist as diatomic molecules - F2, Cl2, and so on. The
intermolecular attractions between one molecule and its neighbours are
van der Waals dispersion forces. As the molecules get bigger there are
obviously more electrons which can move around and set up the
temporary dipoles which create these attractions. The stronger
intermolecular attractions as the molecules get bigger means that you
have to supply more heat energy to turn them into either a liquid or a gas
- and so their melting and boiling points rise.