Dec 25, 2025 · An atom is the basic building block of chemistry. It is the smallest unit into which matter can be divided without the release of electrically charged particles.

atom, Smallest unit into which matter can be divided and still retain the characteristic properties of an element.

An atom is the smallest unit of an element, and each chemical element has a unique atomic number. For instance, hydrogen has an atomic number of 1 because every hydrogen atom has one proton in its …

An atom is the smallest piece of matter that has the characteristic properties of a chemical element, such as hydrogen, oxygen, calcium, iron, gold, and neon. More than 90 types of atom exist in nature, …

ATOM meaning: 1 : the smallest particle of a substance that can exist by itself or be combined with other atoms to form a molecule; 2 : a very small amount of something

The elements are arranged in order of increasing atomic number, which is the number of protons in that atom’s nucleus. Hydrogen, the element with the lowest atomic number, has 1 proton; oganesson, the …

Nov 27, 2025 · In 1932 English physicist James Chadwick discovered a neutral particle of approximately the same mass as the proton and located in the nucleus of the atom. This particle, now known as the …

The mass of an atom consists of the mass of the nucleus plus that of the electrons, so the atomic mass unit is not exactly the same as the mass of the proton or neutron.

An atom has no rigid spherical boundary, but it may be thought of as a tiny, dense positive nucleus surrounded by a diffuse negative cloud of electrons. The value of atomic radii depends on the type of …

An atom is first identified and labeled according to the number of protons in its nucleus. This atomic number is ordinarily given the symbol Z. The great importance of the atomic number derives from the …