in the modern periodic table how do the following properties change on moving from top to bottom and from left to right in a period ?
(a)valency
(b)atomic size
(c)ianization potential
(d)electronegativity
(e)electron affinity
Answers
Answer:
(i) Atomic radius
On moving from left to right across a period, the atomic radius decreases.
With increase in atomic number, the nuclear charge increases but the number of shells in the atoms of all the elements in a period remains the same. The nuclear attraction of the outermost electron increases due to which the atomic radius decreases.
(ii) Electronegativity
On moving from left to right across a period, electronegativity increases.
With increase in atomic number, the nuclear charge increases but the number of shells in the atoms of all the elements in a period remains the same. The nuclear attraction of the outermost electron increases. Hence, tendency to attract shared pair of electrons increases from left to right in a period.
(iii) Ionisation potential
On moving from left to right across a period, ionisation potential increases.
With increase in atomic number, the nuclear charge increases but the number of shells in the atoms of all the elements in a period remains the same. The nuclear attraction of the outermost electron increases due to which ionisation potential increases.
Answer:
(b) atomic size
Explanation:
Electron affinity increases from left to right within a period. This is caused by the decrease in atomic radius. Electron affinity decreases from top to bottom within a group. This is caused by the increase in atomic radius.