unit 1 - the chemistry of life

matter

anything that takes up space and has mass

element

a substance that cannot be broken down into smaller substances

compound

a substance consisting of 2 or more different elements combined into a fixed ratio

essential elements

a substance required for an organism’s normal growth and health

trace elements

required by an organism in very small quantities

bohr model

shows electrons orbiting the nucleus of an atom

lewis dot model

simplified bohr diagrams

octet rule

elements will gain, lose, or share electrons to complete their valence shell and stabilize

covalent bond

when two or more atoms share electrons

covalent peptide bond

bonds that link amino acids together and form the backbone of proteins

ex: polypeptides

nonpolar covalent bond

electrons shared equally between two atoms

polar covalent bond

electrons are not shared equally between 2 atoms

ionic bond

the attraction between oppositely charged atoms

hydrogen bond

partially positive hydrogen atom in one polar covalent molecule will attract to a negative atom in a different polar molecule