Question

What is an atom and a moleule ?
What is the order of magnitude of mass of
one atom? What are isotopes?​

Answer 1

A molecule is defined as the smallest unit of a compound that contains the chemical properties of the compound. Molecules are made up of groups of atoms. Describing the structure of an atom, an atom is also sub-divided into smaller units. Proton, electrons, and neutrons are sub-particles of an atom.

We know, if any atom's atomic mass is in gm unit called gm atomic mass of that atom. And the gm atomic mass is equivalent to 1 mole of that atom. Again 1 mole atom equivalent to Avogadro's number (6.022× 10 exp(23)).

Thus,

Mass of 1 atom = Atomic mass/ Avogadro's number.

Isotopes are versions of the same element. They have the same number of protons and electrons as the element but different mass numbers and number of neutrons.