Question

an ion mass is 40 after the loss of two electrons it will be X++ it has 20 neutrons in it calculate number of protons number of electrons and atomic number​

Answer 1

Concept of Atomic number and Atomic mass

Ion mass = 40

numbers of neutrons = 20

To find :-

Number of protons , electrons and atomic number.

Solution:-

Atomic number → The total number of protons present in an atom is called it's atomic number.

Atomic mass → The sum of total number of protons as well as neutrons is called atomic mass of an element.

Atomic mass = 40

number of neutrons = 20

Number of protons = (Atomic mass - number of neutrons)

Number of Protons = 40 - 20

Number of protons = 20

Atomic number = number of protons

Atomic number (Z) = 20

Number of electrons = ( Atomic number - number of charge on an ion)

Number of electrons = ( 20 - 2 )

Number of electrons = 18

Some useful key points :-

• For neutral atoms number of protons is equal to number of electrons.

• Atom can only loose or gain electrons not protons and neutrons because they lies in nucleus of an atom.

• Number of neutrons is always given by (A -Z) whether the species is neutral or ion.