CHAPTER 2 ATOMS & MOLECULES

most common elements in living things

smallest unit of an element that retains the element's

fixed number of protons in the atomic nucleus

mass of a subatomic particle

the total number of protons neutrons

atoms of the same element with varying numbers of neutrons

unstable and tend to decay to a more stable isotope

regions of 3-D space in which electrons move

outermost electron shell, which the most energetic electrons occupy

small, simple substances (ex: water, simple acids & bases, and simple salts)

large, complex carbon-containing compounds

the sum of the atomic masses of the component atoms of a single molecule

the amount of a compound whose mass in grams is equivalent to its molecular mass

energy necessary to break a chemical bond

share electrons between atoms to fill each atom's valence shell

consists of atoms joined by covalent bonds

unlike atoms linked by covalent bonds (ex methane gas CH4)

a simple way of representing valence electrons by placing dots around the element's chemical symbol

atoms form covalent bonds that require orbitals in valence shells to become rearranged, affecting the shape of the end molecule

measure of an atom's attraction for shared electrons in chemical bonds

covalently bonded atoms with similar electronegativities/ similar shared electrons

covalent bond between atoms that differ in electronegativity

an atom or group

relatively weak bonds that are very important in living organisms

Weak attractions between molecules or parts of molecules that result from transient local partial charges.

occurs when water molecules stick to one another

the ability of water to stick to other substances

tendency of water to move in narrow tubes

occurs when molecules at water's surface crowd together, producing a strong layer

the process in which an ion is surrounded by water molecules arranged in a specific manner

substance that dissociates in solution to yield hydrogen ions & anion; a proton donor

substance that dissociates in solution to yield a hydroxide ion and cation; a proton acceptor

a substance that resists changes in pH when acid or base is added

compound in which the hydrogen ion of an acid is replaced by some other cation