A group is a vertical column of the periodic table. All of the 1A elements have one valence electron. This is what causes these elements to react in the same ways as the other members of the family.

Several groups of representative elements are known by common names. Group 1A(1), the alkali metals, includes lithium, sodium, and potassium. Group 7A(17) the halogens, includes chlorine, bromine, and iodine.

Because the alkali metals are very reactive, they are seldom (if ever) found in their elemental form in nature, and are usually found as ionic compounds (except for hydrogen). The alkali metals have only one valence electron in their highest-energy orbitals (ns1)….Group 1A — The Alkali Metals.

The Group 7A elements have seven valence electrons in their highest-energy orbitals (ns2np5). This is one electron away from having a full octet of eight electrons, so these elements tend to form anions having -1 charges, known as halides: fluoride, F-; chloride, Cl-, bromide, Br-, and iodide, I-.

1- charges

alkali earth metals

Group 5A (or VA) of the periodic table are the pnictogens: the nonmetals nitrogen (N), and phosphorus (P), the metalloids arsenic (As) and antimony (Sb), and the metal bismuth (Bi).

When any of the Group 1 metals is melted, the metallic bond is weakened enough for the atoms to move more freely, and is broken completely when the boiling point is reached. The decrease in melting and boiling points reflects the decrease in the strength of each metallic bond.

All the group 4 hydrides have a regular tetrahedral shape and are non-polar. The only intermolecular forces between such molecules are weak van der Waals’ forces. These generally increase with increasing relative molecular mass.

The partial charges, induced by the higher electronegativity of oxygen, mean that the hydrogens and oxygens will be attracted to one another by coloumbic forces. This in turn will increase the energy needed to pull the molecules apart, thus an increase in the boiling point is observed.

In case of ammonia, due to the presence of electronegative atom, the bond is sufficiently polar to form intermolecular hydrogen bonding. So, boiling point of ammonia is much greater than methane.

London dispersion force

Solids

The Intermolecular force is strongest in solids and weakest in gases.

The three states of matter are: Solids: The strong bonds between molecules make solids rigid and very difficult to deform. Liquids: The relatively weak bonds between molecules allow liquids to be deformed without effort.

gaseous state