brief biochemistry

atoms Smallest unit of matter # of protons = # of neutrons = # of electrons Therefore… NO OVERALL CHARGE Nucleus holds protons (+) and neutrons (0) Orbitals hold electrons (-)

atoms Inner orbital can hold up to 2 electrons Outer orbital can hold up to 8 electrons Electrons on outer-most orbital are called valence electrons “Happy” (stable) atoms have a full outer orbital OR OR

ions When atoms don’t have full outer orbitals, they are not happy (stable)  + - Na Cl Elements with FEWER than 4 valence electrons tend to lose electrons and become POSITIVE Elements with MORE than 4 valence electrons tend to gain electrons and become NEGATIVE If elements loose or gain electrons, they become ions

ions + - Na Cl The positive ion (cation) is attracted to the negative ion (anion) forming an IONIC BOND

molecules A molecule is a group of at least two atoms that are held together The atoms of a molecule are held together by covalent bonds, which are very strong! Covalent bonds occur when atoms that don’t have a full outer orbital SHARE valence electrons

intro to macromolecules Macro = large (Large molecules) Macromolecules are produced by, and found in, living cells Macromolecules consist primarily of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulfur The four main types of macromolecules are carbohydrates, lipids, proteins, and nucleic acids