Question

write group and period of 20ca40 and 17cl35

Answer 1

Given Elements are ⁴⁰Ca₂₀  and ³⁵Cl ₁₇

Calcium Group and period:
atomic number 20:
Electronic configuration : 1s2 2s2 2p6 3s2 3p6 4s2
As differentiating electron is in s block:
Valence electrons :2
Hence group number =number of valence electrons= 2
Period number =4

Chlorine :
Atomic number 17
Electronic configuration: 1s2 2s2 2p6 3s2 3p5
Valence electrons : 7
As differentiating electron is in P block:
Group number= 10 + valence electrons =10+7=17 group
period number=3

Answer 2

Period and group of 20Ca40
Calcium(Ca) is chemical element with the atomic number of 20 and mass number of 40.
The electrons per shell of calcium element is 2.8.8.2.
It also has an electron configuration of 1S2,2S2,2P6,3S2,3P6,4S2.
Hence according to its electron configuration calcium falls under group 2(4S2) of alkaline earth metals and according to its electrons per shell it falls under period 4.

Period and group of 17Cl35
Chlorine(Cl) is a chemical element with atomic number of 17 and a mass number of 35.
It has 2.8.7 electrons per shell and an electron configuration of 1S2,2S2,2P6,3S2,3P5.
According to its electron configuration and electrons per shell it falls under group 7 of halogens and period 3.