Question

Arrange the following elements as in the statement given in brackets. a) fluorine , lithium, carbon , nitrogen ( increasing order of atomic size) . b) potassium, lithium, hydrogen, calcium ( decreasing order of ionisation energy) .

Answer 1

a) fluorine , lithium, carbon , nitrogen ( increasing order of atomic size) .
All given elements belongs to second period.
In period atomic radius decreases as we move from left to right in a periodic table.
Flourine(64 pm) , oxygen(66pm), nitrogen(74pm) , carbon(77pm), Lithium(152pm)

B)potassium, lithium, hydrogen, calcium ( decreasing order of ionisation energy)
All elements belongs to first group except calcium where ionization energy decreases from top to bottom.
Ionization energy is written in eV/atom
Hydrogen(1372.0),Ca(589.8 ), Lithium(520),Potassium (418.8)

Answer 2

According to increasing order of atomic size the elements can be arranged as:

Fluorine - 42 pm, Nitrogen- 56 pm, Carbon - 67 pm, Lithium - 167 pm

The atomic radius is a measure of the size of the atom of a chemical element. It is the mean or typical distance from the centre of the nucleus to the boundary of the surrounding cloud of electrons.

According to decreasing order of ionization energy the elements can be arranged as:

Hydrogen - 13,5984, Calcium - 6,1132, Lithium - 5,3917, Potassium - 4,3407

Ionization energy is the amount of energy which an isolated gaseous atom must absorb, in the ground electronic state, to discharge an electron resulting in a cation. It is expressed as kJ/mol.