Answer:
Detail is given below.
Step-by-step explanation:
Electronic configuration:
[He] 2s² 2p⁵
Number of electron in given atom:
we know that the atomic number of helium is 2 it means it has 2 electron.
Thus the number of electron in given atom are 2+2+5 = 9
Symbol of atom:
The number of electron is the atomic number of an atom. Thus it means the given atom has atomic number 9 which is fluorine.
Symbol = F
Properties of fluorine:
1. it is yellow in color.
2. it is flammable gas.
3. it is highly corrosive.
4. fluorine has pungent smell.
5. its reactions with all other elements are very vigorous except neon, oxygen, krypton and helium.
How many 2s electrons are in atom?
There are 2 electron are present in 2s subshell of fluorine.