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ph scale

used to express the hydroxide ion concentration of a solution; logarithmic

buffer

a substance that acts as a reservoir for hydrogen ions donating them to the solution when their concentration falls and taking them from the solution when their concentration rises

molar concentration

in water this is 10^-7, mol/L

polar molecules

covalently bonded molecules that exhibit charge seperation

cohesion

attraction when other molecules are water

atomic number

the number of protons an atom has

triple bonds

strongest covalent bonds consisting of three pairs of shared electrons

adhesion

attraction when other molecules are of a different substance

hydrogen bonds

interactions that involve bridging hydrogen atoms

surface tension

a tautness of a sruface of a liquid, caused by the cohesion of the molecules of the liquid. water has extremely high surface tension

double bonds

satisfy the octet rule by allowing 2 atoms to share 2 pairs of electrons

radioactive isotops

isotops that undergo nuclear breakup, emitting significant amounts of energy

atoms

matter composed of extremely small particles

water

has a simple atomic structure of 2 hydrogen atoms and 1 oxygen atom and is necessary for life

valence electrons

electrons in the outer energy levels of different elements

energy level

electrons that are the same distance from the nucleus and therefore have the same energy, even if they occupy different orbitals

hydroxide ion

the rest of the dissociated water molecule, which has retained the shared electron of the covalent bond, is negatively formed

mole

the weight in grams that corresponds to the summed atomic masses of all the atoms in a molecule

matter

any substance in the universe that has mass and occupies space

specific heat

the amount of heat that must be absorbed or lost for 1 gram of a substance to change its temperature 1 degrees C

products

molecules resulting from a chemical reaction

neutron

a subatomic particle that carries no charge and is found in the nucleus of all known atoms but hydrogen

hydrophobic exclusion

the tendency of nonpolar molecules to aggregate in water

reactants

original molecules before a reaction starts

electronegativity

a property of the atom nuclei that refers to the affinity of the nuclei for valence electrons

hydrogen ion

when a dissociated proton is no longer counterbalanced it becomes a positively charge hydrogen ion

oxidation

loss of an electron by an atom or molecule

compound

a molecule that contains atoms of more than one element

heat of vaporization

energy required to change one gram of liquid water into a gas

octet rule

rule of eight. atoms tend to establish completely full outer energy levels

hydrophobic

when nonpolar molecules shrink from contact with water

reduction

the gain of an electron by an atom, often with an associated proton

anion

negatively charge ion

single bonds

only one electron pair is shared

molecular formulas

represented as, for examples, H2 and O2 for hydrogen gas and oxygen

ions

atoms or molecules containing an unequal number of electrons and protons and therefore carry a net positive or net negative charge

half- life

the time it takes for one-half the atoms in a radioactive sample decay

molecule

atoms that are joined together in clusters

covalent bonds

formed when 2 atoms share one or more pairs of valence electrons

structural formulas

represented as H-H or O=O

hydrophillic

when polar molecules readily form hydrogen bonds with water

protons

particles in a nucleus that carry a positive charge

neutral atoms

atoms with the same number of protons and electrons that are electrically neutral, having no net charge

ionic bonds

when atoms with opposite electrical charges attract

electrons

orbitting cloud of tiny, negatively-charged subatomic particles that every atom posesses

ionization

the process of spontaneous ion formation

isotopes

atoms of an element that posess different numbers of neutrons

cation

positively charge ion

ionic compound

an attraction of ions of opposite charge in an ionic compound

hydration shell

formed when a sucrose molecule dissociates or breaks away from a crystal to prevent it from associating with other sucrose molecules. water molecules surround it in a cloud

orbital

the area around a nucleus where an electron is most likely to be found

chemical bonds

the joining of atoms in a molecule

atomic mass

equal to the sum of the masses of an atom's protons and neutrons

element

any substance that cannot be broken down to any other substance by ordinary chemical means

chemical bonds

the formation and breaking of chemical bonds, the essence of chemistry

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