• 2.1: Atoms and Molecules

    Atoms and elements are the smallest structures in the universe. These substances cannot be broken down any further. Elements come together to form molecules which are the building blocks of the lowest level of life, the cell. To understand biology, you need to understand these foundation elements that form the structures of life.

    The primary subatomic particles are protons, neutrons, and electrons. Protons and neutrons make up the nucleus of an atom. Electrons are found outside the nucleus. A proton has an electrical charge of +1. A neutron is nearly identical in size to a proton, but it has no charge. An electron is much smaller than a proton or neutron. An electron is also a charged particle. Despite being much smaller than a proton, the charge of an electron is equal in magnitude to the charge of a proton. However, the charge is opposite, so each electron has a charge of -1.