Solution: We are taking second element from the 4th period.
Element's name is Calcium.
It's symbol is Ca.
It is a metal because it looses its valence electron to form positive ions.
Calcium element lies in the second group of 4th period. The elements belonging to the second group are known as alkaline earth metals.
Atomic Number of Calcium = 20
Atomic number = Number of protons = Number of electrons
therefore,
Number of electrons and protons = 20
Atomic Mass of Calcium = 40
Atomic Mass = Number of neutrons + Number of proton
bu substituting the values of atomic mass and number of prtons, neutrons can be calculated
Number of neutrons = 20.