Question

1. (i) State modern periodic law.
(ii) Name the scientist who stated the law.
(iii) How many groups and periods does modern
periodic table have?
2. What are horizontal rows and vertical columns in a
periodic table known as ?
3. Periodicity is observed due to similar
(number of valence electrons/atomic number!
electronic configuration).
4. How does the electronic configuration in atoms change
(i) in a period from left to right?
(ii) in a group from top to bottom ?​

Answer 1

Answer:

1.properties of elements are in periodic functions of their atomic numbers.

i.Henry Moseley

ii.there are 7 periods and 18 groups in modern periodic table

2.horizontal rows are called periods and vertical columns are called groups

3.Periodicity is observed due to similar electronic configuration

4.i.Though the number of shells remain the same, number of valence electrons increases by one, as we move across any given period from left to right.

(ii) While going from top to bottom in a group, the number of shells increases successively i.e. one by one but the number of valence electrons remains the same

Answer 2

1a) Modern periodic law stated that the properties of the periodic functions are the atomic number

b)Henry Moseley

c)18 groups and 7 periods

2) Vertical columns are groups and horizontal rows are periods.