An element ‘X’ has mass number 35 and 18 number of neutrons. Therefore, Electronic configuration of X= 2, 8, 7. Write atomic number and electronic configuration of ‘X’. Also write group number, period number and valency of ‘X’.
Answer
Mass number = 35
Number of neutrons = 18
- Mass number = number of neutrons + number of protons
Therefore, number of protons = Mass number - number of neutrons
= 35 - 18
= 17
- Atomic number = number of protons = 17
- Therefore, the electronic configuration of X is 2, 8, 7
- Group number = 10 + number of valence electrons = 10 + 7 = 17
- Since there are 3 shells, period number is 3.