Question

Define mass no. and atomic number

Answer 1

Atomic number refers to the no. of protons in the nucleus of an element.
For example : Atomic no. of Hydrogen is 1.

Mass number is the average of protons and neutrons in the nucleus of all existing isotopes of an element.

Answer 2

☛ Atomic number:-This number shows the position of an element in the periodic table .The number of protons present in the nucleus or the number of electrons present outside the nucleus of an atom of an element is known as atomic number.It is denoted by Z .

☛ Atomic mass :- The atomic mass of an element is a number which express as to how many times an atom of the element is havier than 1/12th of the mass of carbon atom (C¹²).

Atomic mass = Mass of an atom of element / 1/12 mass of a carbon atom (C¹²).

☛ Mass number :- The sum of neutrons and protons present in the nucleus of an atom is called mass number.It is denoted by A.

Mass number = No.of Neutrons + No.of Protons

or,

A = n + p

let's know about atom

☛ Atom :- An atom is the smallest part of an element in which all the properties of the matter remains alike and which participates in a chemical reaction.It is not capable of independent existence.

The size of an atom is very small and the mass is even less.

Hydrogen atom is the smallest and lightest.

Its radius is around