What is difference between atomic mass and mass number?

Answer 1

Atomic Mass is the average of the masses of the naturally existing (i.e. mixture of) isotopes of one specific element.

Mass number is the sum of protons and neutrons in the atomic nucleus of an isotope.

Atomic mass: the mass of an isotope in the neutral state expressed in 1/12 from the mass of 12C.

IUPAC recommend the use of the expression atomic mass for isotopes and atomic weight for chemical elements.

Answer 2

Atomic number is the number which confirms the name of the atom. Hence atomic number. This equals the number of protons in the nucleus. Symbol is Z.

Where as the atomic mass is the mass content in an atom. This equals to the sum of mass of protons, neutrons and electrons.

Better know about the mass number (A) too. Mass number is the sum of protons and neutrons in the nucleus. Here electron is excluded because of its comparatively low mass. Mass of an electron is 1/1836 of a proton or neutron

In chemistry, they wont differentiate mass and weight. They mean these two one and the same. But in Physics there is vast difference between mass and weight.

So atomic mass and atomic weight are used in equal sense.

Mass number will be helpful in getting the atomic mass. For example, in case of chlorine there are two isotopes. 17 is its atomic number. But number of neutrons differ by 2. One is having 18 neutrons and other one is having 20 neutrons. So two mass numbers are available and they are 35 and 37.

But the percentage of existence of these two isotopes is not 50 - 50. Isotope -35 is much more compared to the isotope - 37. So its average atomic mass will be 35.45

Answer 3

Atomic Number is the number of pussy's OR Protons. the Mass Number is the number of protons + the number of neutrons.

neutrons have 1 mass, no charge

Protons have 1 mass, +1 charge

Electrons have negligable mass, -1 charge

Alpha Particles are 4 mass, +2 charge

Beta Particles are negligable mass, -1 charge