Q. Consider the following statements
I. The radius of an anion is larger than that of the parent atom.
II. The ionization energy generally increases with increasing atomic number in a period.
III. The electronegativity of elements increases on moving down across a group.
Which of the above statements is/are correct?

 2621  186 Classification of Elements and Periodicity in Properties Report Error

Solution:

I.T he radius of an anion is larger than that of parent atom. When an electron is added to an atom, the effective nuclear charge decreases and the electrons get away from the nucleus and the anion becomes larger than the corresponding atom.
II. The I.E. increases from left to right in a period generally due to increase in the nuclear charge and decrease in the atomic radii across the period.
However, there are some breaks where an electron of a somewhat stable configuration is removed.
III. The electronegativity of an element is the tendency of an atom in a compound ( and not an isolated atom) to attract a pair of bonded electrons towards itself. The tendency to attract an electron of an isolated atom is measured by electron affinity.