 # What is Atomic Number and Mass Number? CBSE NCERT Notes for Class 9 Science Chapter 4 Structure Of The Atom

CBSE NCERT Notes for Class 9 Science Chapter 4 Structure Of The Atom​

Chapter 4 Structure of NCERT Solutions for Class 9 Science At skillyogi, the Atom gives students with answers to all of the questions in the NCERT Class 9 textbook, which is aligned with the CBSE board.

This page offers students with study source material that has been compiled by a team of subject-matter experts. Solving NCERT Solutions for Class 9 Science enables students to get the highest score on the CBSE Class 9 Science Term II test.

CBSE Class 9 Science notes will assist students in studying the topic thoroughly and clearly.

These CBSE Class 9 Science notes were written by subject experts who made the study material very basic, both in terms of language and format.

## Fill Up The Form & Our Team Will Provide You With All Help

What is Atomic Number and Mass Number?

Atomic Number

It is defined as the number of protons in an atom’s nucleus. Each atom of the same element has the same number of protons in its nucleus, giving it the same atomic number. Zand is signified by a subscript to the left of the symbol, e.g. I He, ; Li, where

Z = 2 and 3 for He and Li, respectively.

Mass Number

It is defined as the sum of the protons and neutrons in an atom’s nucleus. Nucleons are made up of protons and neutrons. A is used to signify the mass number. The mass number (A) is equal to the sum of the protons and neutrons. For example, I He, ;Li, where A equals 4 and 7 for He and Li, respectively.

Number of neutrons = Mass number – atomic number

(-.• Atomic number = Number of protons)

To the left of the symbol, the mass number is represented as a superscript.