Final answer:
Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons, leading to different mass numbers but the same atomic number. They have similar chemical properties but can vary in physical properties like stability and radioactivity.
Step-by-step explanation:
Definition of Isotopes
Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons. This means that while they occupy the same position on the periodic table (the same atomic number), they have different mass numbers. Isotopes are particularly interesting in the study of chemistry and physics for various applications, including radioactive dating and nuclear medicine.
As an example, carbon-12 and carbon-14 are both isotopes of carbon. They each have 6 protons, which classifies them as carbon, but carbon-12 has 6 neutrons whereas carbon-14 has 8 neutrons. This difference in neutron count affects their mass and some properties, such as stability and radioactive behavior. Despite these internal differences, isotopes of an element generally exhibit similar chemical behavior because their electron arrangements are identical.
The discovery of isotopes refuted an early assumption made by John Dalton in 1804 that all atoms of a given element are identical. The term itself, derived from the Greek isos (equal) and topos (place), underscores that isotopes of an element share the same 'place' or position in the periodic table.