Introduction: The components that make up living things are made of smaller molecules that are stuck together by chemical means. Proteins, lipids, carbohydrates, and nucleic acids are all made up of carbon, hydrogen, and oxygen atoms, with proteins and nucleic acids also having nitrogen. These atoms are stuck together to form these large molecules by bonding together. Bonding involves the sharing or the donation and accepting of electrons. The outermost electrons in an atom are called valence electrons, and are the ones that either get donated/accepted or shared.

This diagram shows a special compound called a carboxyl group. The dark lines indicate that electrons are being shared between the carbon (C) and the other atoms.

Most molecules and compounds that are important to life are bonded covalently, meaning they are sharing electrons. Salt, which is not an organic molecule but is important to life, is bonded ionically. It is made of atoms that have donated/accepted electrons.

Directions for this Lesson: Answer the practice questions and then watch the video to learn more about the different types of bonds.