Isotopes
Isotopes are atoms of the same element with the same number of protons (Z) but different number of neutrons (N). Isotopes of the same element have the same number of electrons. Thus, isotopes have the same proton number but different nucleon numbers (A).
Example: 11H 12H 13H
Isobars
Elements having the same mass number (A) but different number of protons (Z) are isobars.
Example: 4016S, 4017Cl, 4018Ar, 4019K, and 4020Ca.
Isotones
Elements having the same number of neutrons (N) but a different number of protons (Z) or mass number (A) are isotones.
Example: 3616S, 3717Cl, 3818Ar, 3919K, and 4020Ca
Isomers
Isomers are molecules with identical molecular formula but different structure (distinct arrangements of atoms).
Example: butane and isobutane
butane: CH3-CH2-CH2-CH3
isobutane: CH3-CH(CH3)-CH3
