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Learning path: Chemical Bonds

The concepts to learn before Chemical Bonds, in order. Each step links to its page and, where one exists, its quiz.

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Your path

  1. AtomsDirect prerequisite

    An atom is the smallest unit of an element that keeps that element's chemical identity. Every atom has a tiny, dense nucleus of protons and neutrons, which holds nearly all of its mass, surrounded by electrons that fill almost all of its volume. The number of protons fixes which element the atom is; changing the number of electrons makes an ion, and changing the number of neutrons makes a different isotope.

    Take the Atoms quiz

  2. Periodic TableDirect prerequisite

    The periodic table lists every known element in order of atomic number, in 7 rows (periods) and 18 columns (groups). Elements in the same group have similar outer-electron arrangements and so behave in similar ways, which lets chemists predict properties from position. Mendeleev's 1869 version was so successful that it predicted elements nobody had yet found; the seventh period was completed in 2015.

    Take the Periodic Table quiz

  3. A chemical bond is the attraction that holds atoms together in a substance. In an ionic bond, oppositely charged ions attract after electrons have moved from one atom to another; in a covalent bond, two atoms share a pair of electrons; in a metal, outer electrons are shared across the whole structure. Bonding lowers a system's energy, so breaking a bond always costs energy and forming one releases it.

    Take the Chemical Bonds quiz

Where to go next

Concepts that build directly on Chemical Bonds:

  • Molecules: A molecule is a group of atoms held together by covalent bonds that acts as a single particle — such as water, H₂O, or carbon dioxide, CO₂. A molecular formula says which atoms a molecule contains and how many; its three-dimensional shape, which VSEPR theory predicts from repelling electron groups, strongly affects how it behaves. Chemists count molecules in moles: exactly 6.022 140 76 × 10²³ of them.