Atom vs. Isotope — What's the Difference?

An atom is the smallest unit of ordinary matter that forms a chemical element. Every solid, liquid, gas, and plasma is composed of neutral or ionized atoms.

Isotopes are two or more types of atoms that have the same atomic number (number of protons in their nuclei) and position in the periodic table (and hence belong to the same chemical element), and that differ in nucleon numbers (mass numbers) due to different numbers of neutrons in their nuclei. While all isotopes of a given element have almost the same chemical properties, they have different atomic masses and physical properties.The term isotope is formed from the Greek roots isos (ἴσος "equal") and topos (τόπος "place"), meaning "the same place"; thus, the meaning behind the name is that different isotopes of a single element occupy the same position on the periodic table.

A part or particle considered to be an irreducible constituent of a specified system.

One of two or more atoms having the same atomic number but different mass numbers.

The irreducible, indestructible material unit postulated by ancient atomism.

(nuclear physics) Any of two or more forms of an element where the atoms have the same number of protons, but a different number of neutrons within their nuclei. Thus, isotopes have the same atomic number but a different mass number.

An extremely small part, quantity, or amount.

To define or demonstrate an isotopy of (one map with another).

The smallest unit of an element, having all the characteristics of that element and consisting of a very small and dense central nucleus containing protons and neutrons, surrounded by one or more shells of orbiting electrons. Atoms remain undivided in chemical reactions except for the donation, acceptance, or exchange of valence electrons.

One of two or more atoms with the same atomic number but with different numbers of neutrons

This unit regarded as a source of nuclear energy.

The smallest possible amount of matter which still retains its identity as a chemical element, now known to consist of a nucleus surrounded by electrons.

(history of science) A hypothetical particle posited by Greek philosophers as an ultimate and indivisible component of matter.

The smallest, indivisible constituent part or unit of something.

(philosophy) In logical atomism, a fundamental fact that cannot be further broken down.

(historical) The smallest medieval unit of time, equal to fifteen ninety-fourths of a second.

A mote of dust in a sunbeam.

A very small amount; a whit.

An individual number or symbol, as opposed to a list; a scalar value.

(mathematics) A non-zero member of a partially ordered set that has only zero below it (assuming that the poset has a least element, its "zero").

An element of a set that is not itself a set; an urelement.

An age group division in hockey for nine- to eleven-year-olds.

An ultimate indivisible particle of matter.

The smallest particle of matter that can enter into combination; one of the elementary constituents of a molecule.

Anything extremely small; a particle; a whit.

To reduce to atoms.

(physics and chemistry) the smallest component of an element having the chemical properties of the element

(nontechnical usage) a tiny piece of anything