the periodic table of chemical elements: 1. Ionisation potential gradually decreases along a period
the periodic table of chemical elements:
1. Ionisation potential gradually decreases along a period
2. In a group of elements, electron affinity decreases as the atomic weight increases
3. In a given period, electronegativity decreases as the atomic number increases
Which of these statement (s) is/are correct?
(a) 1 only (b) 2 only (c) 1 and 3 (d) 2 and 3
1 Answers
(b) The electron affinity of a molecule or atom is the energy change when an electron is added to the neutral atom to form a negative ion. This property can only be measured in an atom in gaseous state.
X + e– → X–
Down a group, the electron affinity decreases because of a large increase in the atomic radius, electronelectron repulsion and the shielding effect of inner electrons against the valence electrons of the atom. As one moves from left to right across a period in the periodic table, the electronegativity increases due to the stronger attraction that the atoms obtain as the nuclear charge increases. There will be an increase of ionization energy from left to right in a given period.