Question

define descriptively atom what is atomic mass and number ​

Answer 1

Explanation:

The mass number (symbol A, from the German word Atomgewicht [atomic weight]), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus.

Answer 2

Answer:

The mass number (symbol A, from the German word Atomgewicht [atomic weight]), also called atomic mass number or nucleon number, is the total number of protons and neutrons (together known as nucleons) in an atomic nucleus. ... The mass number is different for each different isotope of a chemical element.