Atomic number and Mass number|Chapter#2|Lec#7|9th Class New Chemistry 2025|PCTB скачать в хорошем качестве

Atomic number and Mass number|Chapter#2|Lec#7|9th Class New Chemistry 2025|PCTB

#atomic mass #atomicnumber #massnumber #nucleon number #formula to calculate the number of neutrons #9thclasschemistry #newbook #chapter2 #punjabtextbookboard #curriculum #ptcb #ptb #pctb #education #chemistry Atomic Number (Z) and Mass Number (A) are two fundamental concepts in chemistry that describe the properties of atoms. Atomic Number (Z) 1. *Definition*: The atomic number is the number of protons present in the nucleus of an atom. 2. *Unique identifier*: Atomic number uniquely identifies an element and determines its position in the periodic table. Mass Number (A) 1. *Definition*: The mass number is the total number of protons and neutrons present in the nucleus of an atom. 2. *Sum of protons and neutrons*: Mass number is the sum of the number of protons (atomic number) and the number of neutrons. Key differences: 1. *Atomic number vs. Mass number*: Atomic number is the number of protons, while mass number is the total number of protons and neutrons. 2. *Uniqueness*: Atomic number uniquely identifies an element, while mass number can vary for different isotope Example: Atomic number of carbon (C) = 6 (number of protons) Mass number of carbon-12 (C-12) = 12 (6 protons + 6 neutrons) In summary, atomic number defines the identity of an element, while mass number provides information about the specific isotope of that element. #chemistry by Shoaib Javed #représentation of atomic number and mass number.