The Periodic Law states. "The physical and chemical properties of elements are periodic functions of their atomic

"The physical and chemical properties of elements are periodic functions of their atomic number"

Explanation:

The physical and chemical properties of elements are periodic functions of their atomic number.

The properties followed the trends in periodic law includes

atomic radii, electronegativity, ionization energy, electron affinity.

Trends along period.

As we move from left to right across the periodic table the number of valance electrons in an atom increase. The atomic size tend to decrease in same period of periodic table because the electrons are added with in the same shell. When the electron are added, at the same time protons are also added in the nucleus. The positive charge is going to increase and this charge is greater in effect than the charge of electrons. This effect lead to the greater nuclear attraction. The electrons are pull towards the nucleus and valance shell get closer to the nucleus. As a result of this greater nuclear attraction atomic radius decreases and ionization energy increases because it is very difficult to remove the electron from atom and more energy is required. The electron affinity and electronegativity increases as we move left to right.

Trends along group:

As we move down the group atomic radii increased with increase of atomic number. The addition of electron in next level cause the atomic radii to increased. The hold of nucleus on valance shell become weaker because of shielding of electrons thus size of atom increased. Ionization energy decreased. The electron affinity and electronegativity also decreased as we move down the group.