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55 terms

Ap bio chapter 2

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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