Question

1. Define the following.
a. Atomic number
b. Atomic mass number
c. Isotopes

Answer 1

Answer:

Ans:Atomic number: Number of electrons (or) Number of

protons present in an atom is called atomic number.

Atomic mass number (or) Mass number: Total number of

protons and neutrons (or) Number of nucleons are called

atomic mass number or mass number.

Isotopes: The atoms which have the same number of protons,

but a different number of neutrons are called isotopes.

Answer 2

(a) ans:-

the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table.

(b) ans:-The mass number, also called atomic mass number or nucleon number, is the total number of protons and neutrons in an atomic nucleus. It is approximately equal to the atomic mass of the atom expressed in atomic mass units.

(c)answer:- isotopes

isotopeseach of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element.

isotopeseach of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties; in particular, a radioactive form of an element."some elements have only one stable isotope"