Elements and atomic number | Atoms, isotopes, and ions | High school chemistry | Khan Academy

Atoms: The basic unit of matter, consisting of protons, neutrons, and electrons.

Isotopes: Variants of a particular chemical element that have the same number of protons but different numbers of neutrons, affecting their atomic mass.

Ions: Atoms or molecules that have gained or lost one or more electrons, resulting in a net charge.

Atomic Number: The number of protons in the nucleus of an atom, which determines the element's identity and its position on the periodic table. The atomic number is unique to each element, meaning that no two elements can have the same atomic number. The atomic number also plays a critical role in determining the chemical properties of an element, as it influences how atoms interact and bond with one another.

Mass Number: The total number of protons and neutrons in an atom's nucleus, which helps distinguish between different isotopes of the same element.

Isotopes: Variants of a particular chemical element that have the same number of protons but different numbers of neutrons, leading to different mass numbers. This variation can affect the stability and radioactive properties of the element.