Question

The atomic radii of the first group elements are given below : [Group-I element - Atomic Radii (pm)] $\mathrm{Na}-86,\mathrm{K}-231,\mathrm{Rb}-244,\mathrm{Cs}-282$. State the reason behind the observed trend in the above elements.

Answer 1

• Group 1 component Atomic radius (pm) of $\mathrm{Li},\mathrm{Na},\mathrm{K},\mathrm{Rb},\mathrm{Cs}$ is 152, 186, 231, 244, and 262.
• Component $\mathrm{Li}$ has the smallest atom, with an atomic radius of 152 Pm, whereas the biggest atom belongs to the element Cs (atomic radius 262 Pm).
• We conclude that the atomic size (or radius) increases along the group as a result of this arrangement.

Atomic radius:

• The distance between an atom's central nucleus and its outermost shell is known as its atomic size.
• In a molecule, an atomic radius is equal to half the distance between neighboring atoms of the same element.
• By measuring the separation between the two atoms when two atoms are merged, we may determine the size of the combined atoms.
• The alternative technique involves creating a single covalent link between two atoms and measuring the distance between them in order to determine the atomic size of a non-metallic element.
• The radius determined using this technique is referred to as the element's covalent radius.
• It is known as a metallic radius in the case of metal. Half of the total distance between the nuclei of two adjacent metal ions connected by a metallic link is what is meant by this term.
• An atom's radius increases in direct proportion to its atomic number.
• As you move straight down a certain column on the periodic table, the radius of each consecutive neighboring atom increases.
• The number of entire periods increases as you move down the periodic table.