By Kofi Bofah – Updated Aug 30, 2022
Atoms consist of a positively charged nucleus—made of protons and neutrons—surrounded by a cloud of negatively charged electrons. Elements are defined by the number of protons in the nucleus; atoms sharing the same proton count belong to the same element. Molecules form when two or more atoms bind together. An ion is an atom or molecule that has gained or lost one or more electrons, giving it a net charge.
Electrons carry a negative charge; protons are positive; neutrons are neutral. In a neutral atom, the numbers of protons and electrons balance, resulting in no overall charge. When an atom loses electrons, it becomes a positively charged cation; gaining electrons produces a negatively charged anion.
Neutral atoms are generally stable because they have balanced charge. Ionization—the process of adding or removing electrons—creates ions that are less stable on their own. Ions are attracted to oppositely charged partners, often leading to the formation of ionic compounds.
Compounds are substances composed of at least two different elements. Ionic compounds arise when oppositely charged ions combine, while covalent compounds result from atoms sharing electrons.
Atoms are held together by nuclear forces within the nucleus and electromagnetic forces between charged particles. Covalent bonds form when atoms share electrons to achieve stable electron configurations. Ionic bonds arise from electrostatic attraction between cations and anions.
