smaller because the remaining electrons are at a inner cells and attracted more strongly by the nucleus. Fluorine and chlorine become negative ions by gaining an electron. When electrons are added, the charge on the nucleus is not great enough to hold the increased number of electrons as closely as it holds the electrons in the neutral atom. So, as seen in atomic radius, ionic radii also decrease along the period from left to right and increase down the group.
. . Ionisation Energy Ionisation energy is the minimum energy required to remove an electron from Li Radii in Picometers Li + F F – Na Na + Cl Cl – Figure . Relative ionic radii of cation and anion Periodic Classificaiton of Elements an isolated gaseous atom in its ground state to form a cation.
It is otherwise called ionisation enthalpy. It is measured in kJ/mol. Higher the ionisation energy, it is more difficult to remove the electron. As the atomic size decreases from left to right in a period, more energy is required to remove the electrons.
So, the ionisation energy increases along the period. But, down the group, the atomic size increases and hence the valence electrons are loosely bound. They require relatively less energy for the removal. Thus, ionisation energy decreases down the group in the periodic table.
. . Electron Affinity Electron affinity is the amount of energy released when an isolated gaseous atom gains an electron to form its anion. It is also measured in kJ/mol and represented by the following equation: A (g) + e – → A – (g) + Energy Cl (g) + e – → Cl – (g) + energy Like ionisation energy, electron affinity also increases from left to right in a period and decreases from top to bottom in a group.
More to Know Noble gases show no tendency to accept electrons because the outer s and p orbitals of noble gases are completely filled. No more electrons can be added to them and hence their