Biology - Unit 1: Chemistry of Life

flashcards for Unit 1 of AP Biology; updated as of 2026

covalent bonds

bonds between atoms to fill their valence electron shells

nonpolar

equal sharing of electrons - no charge

polar

unequal sharing of electrons - has a charge

hydrophilic

dissolves in water

hydrophobic

doesn’t dissolve in water

hydrogen bonds

attraction between oxygen and hydrogen due to the polarity of water molecules

evaporation

kinetic energy between water molecules on the surface releases some into the atmosphere

solvent

a substance that dissolves stuff

sphere of hydration

water molecules surround the substance they bond to

cohesion

water’s tendency to stick to itself - causes surface tension

adhesion

attraction between water molecules and other molecules - causes a meniscus and capillary action

isotopes

different forms of an element that has a different amoun of neutrons

atomic mass

mean mass of an element’s isotopes

orbitals

sets of electron shells represented by “n” in the Bohr model

octet rule

states that atoms are the most stable when tehy have 8 electrons in their valence (outermost) shell

cations

positive ions; lose electrons

anions

negative ions; gain electrons

covalent bonds

strong bond when two atoms share electrons

aliphatic hydrocarbons

linear chains of carbon

aromatic hydrocarbons

closed rings of carbon

isomers

molecules that have the same chemical composition but different structures

hydroxyl

polar

methyl

R-CH_³