Question

Describe the trend of ionization potential along a period and a group in the periodic table.

Answer 1

Ionization energy:

• It is the minimum amount of energy required to remove the outermost electron from an isolated neutral gaseous atom of that element in its lowest energy state to form a positive ion (cation). This energy is called the first ionization energy/potential.

Ionization potential:

• The minimum amount of energy required to remove the electron from a gaseous atom is called its ionization potential.
• The second ionization potential is the energy required to remove the electron from the outermost shell of a unit positively charged gaseous ion.
• Variation of ionization potential down the group:
• The ionization potential decreases from top to bottom in a group as the atomic size increases down the group, thus resulting in the decrement of the nuclear force of attraction towards the electron to be removed.
• Variation of ionization potential along a period:
• Generally, the Ionization potential increases from left to right along a period. The reason for this can be that along a period, the atomic size decreases and the valence shell is closer to the nucleus. Thus more energy is required to remove an electron from the valence shell.
• Ionization potential along a period increases and decreases down a group in the periodic table.