Question

What is meant by atomic radius explain why it decreases across a period

Answer 1

The distance between the centre of the nucleus of an atom to the outermost electron shell is known as the atomic radius of the circle.

The atomic radius decreases a cross a period because as the number of electrons increase in the shell then the nucleus exerts a greater attraction and pulls the electron towards the nucleus and this the distance decreases.

Answer 2

atomic radius is usually defined as the distance between the outermost orbit and the centre of the nucleus of the atom .

in a period the atomic number increases left to right this means that the number of electrons in an atom increases the extra electron goes to the same shell .The increase positive charge in the nucleus attracts the electron towards nucleus the size of the atom thus decreases