State whether ionization energy increases or decreases on moving from left to right in a period of the periodic table.
State whether ionization energy increases or decreases on moving from left to right in a period of the periodic table.
Step-1: Introduction
The ionization energy is the energy needed to separate an electron from the outer shell of isolated atom. It is denoted as IE. The atomic size, effective nuclear charge and screening effect are the factors that influence the ionization energy.
Step-2: Trend of ionization energy
The ionization energy enlarges on moving from left to right across the period due to the decrease in size of atom on increasing the atomic number and thus, the electrons in valence shell goes nearer to the nucleus. There is more energy needed to separate an electron from outermost shell.
Example: Carbon () has more ionization energy than Boron ().
The ionization energy decreases down the group because of the increase in number of valence shells.
Final answer
Therefore, ionization energy increases down a group of the periodic table.
Step-1: Introduction
The ionization energy is the energy needed to separate an electron from the outer shell of isolated atom. It is denoted as IE. The atomic size, effective nuclear charge and screening effect are the factors that influence the ionization energy.
Step-2: Trend of ionization energy
The ionization energy enlarges on moving from left to right across the period due to the decrease in size of atom on increasing the atomic number and thus, the electrons in valence shell goes nearer to the nucleus. There is more energy needed to separate an electron from outermost shell.
Example: Carbon () has more ionization energy than Boron ().
The ionization energy decreases down the group because of the increase in number of valence shells.
Final answer
Therefore, ionization energy increases down a group of the periodic table.
