This makes the electron closer to the nucleus which causes the atomic size to decrease. As we move from left to right in the periodic table, the positive charge on the nucleus or the effective nuclear charge increases making the attraction of the outer electron to increase.

In the periodic table, the atomic radius of the element decreases from left to right in a period. I.e Van Der Waals radius > Metallic radius > Covalent radius Van der Waal’s radius is measured by taking half of the internuclear separation between two atoms of the same element adjacent to each other in their solid state. Therefore, their radius is measured using Van der Waal’s method. Atomic radii can also be measured by X-ray and other spectroscopic methods.Īlternatively, the noble gases are monatomic and their non-bonded radii values are very large. Likewise, depending on whether the element is metallic or non-metallic, the atomic radius can be referred to both covalent and metallic radius. For example, the covalent radius of an element is measured by taking half of the distance between two atoms bound together by a single bond whereas a metallic radius can be calculated by taking half the internuclear distance separating the metal cores in the metallic crystal. An estimate of atomic radii can be made by knowing the distance between atoms in a combined state. Hence, the determination of atomic size cannot be precise. Since an electron cloud surrounds an atom, it does not have sharp boundaries. The atomic radius is a distance from the centre of the nucleus to the outermost shell of the electrons in the atom of any element.

Atomic size trend