Chemistry of Life Flashcards
element
a pure substance that cannot be broken down (periodic table of elements); 92 occur naturally ; 4 are essential to life
atom
the building block of matter
nucleus
center of an atom; it has protons and neutrons
isotope
atoms of the same element with a different number of neutrons; often used in medicine (radioactive) and carbon dating
compound
a substance made of two or more elements bonded together in fixed proportions (H + 0»_space; water; sodium + chlorine»_space;salt)
covalent bond
when atoms share one or more pairs of electrons
molecule
two or more atoms held together by covalent bonds
ion
an atom that has gained or lost one or more electrons
(# protons no longer equals # electrons)
cation = positive charge (lost electrons)
anion = negative charge (gained electrons)
ionic bond
atoms exchange electrons
pH
the measure of hydrogen ions in a solution
acid
high # of hydrogen ions (low number on pH scale)
base
low # of hydrogen ions (high number on pH scale and high # of hydroxide)
polarity
having two opposite poles
atomic number
number of protons
atomic MASS
n + p
to find the number of neutrons
atomic mass - protons = neutrons
buffer
resists change in pH
hydrogen bond
attractive force between H and another atom - allows for water to have special qualities
cohesion
molecules of same substance “stick” together (penny demo)
adhesion
molecules of different substances “stick” together
surface tension
cohesion on a large scale creates a “surface” (ex. water bug)
universal solvent
water breaks up many substances (because of the polar ends of the H bonds)
high heat of vaporization
when water goes from liquid to gas, it takes a lot of energy
less dense as a solid
ice floats (air gets trapped in the open spaces of the molecule as water freezes)
high specific heat
it takes a great amount of energy to heat water
