Question

define the terms:-
valency
valence electrons
atomic number
mass number

Answer 1

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VALENCY:
The number of electrons an atom can gain, lose or share.


VALENCE SHELL:
The electrons present in the outermost shell are called valence electrons.


ATOMIC NUMBER:
The number of protons present in the nucleas of an atom. In an uncharged atom it is equal to number of electrons.
Symbol of atomic number is " Z ".


MASS NUMBER :
It is the total number of protons and neutrons present in an atom. Also known as atomic mass number.
Symbol of mass number is " A ".

Answer 2

• Valence is simply defined as the combining power of atoms
• Valence electrons refer to the electrons in the outer shell of an atom whihc determine the chemical properties of an atom
• Atomic number refers to the number of protons present in an atom
• Mass number refers to the sum of all protons and electrons in an atom