Unit 2 Flashcards
matter
anything that takes up space and has mass
element
a substance that cannot be broken down to other substances by chemical reactions
compound
a substance consists of 2 or more types elements, Ex H20
trace elements
elements found in small quantities
neutrons and protons form
atomic nucleus
electrons form
a ring around the nucleus
daltons
the atomic mass unit
atomic number
the number of protons in its nucleus
mass number
the sum of protons + the neutrons in the nucleus
isotopes
2 atomic forms of an element that differs in number of neutrons
radioactive isotopes
Decays spontaneously and lose subatomic particles, give off particles and energy
energy
the capacity to cause change
potential energy
the energy that matter has b/c of the location or structure
reactivity of an atom…
derives from the presence of 1+ more unpaired electrons in the valence shell
inert (unreactive) atoms
atoms with completed valence shells
covalent bond
the sharing of a pair of valence electrons by 2 atoms. One of the strongest bonds.
molecule
2+ atoms held together by covalent bond
bonding capacity
the number of electrons required to complete the atom
pure elements
molecules composed of 1 type of atom, Ex: H2
electronegativity
an atom’s attraction for the electrons of a covalent bond. The more electronegative, the more stronger the electrons pull toward itself.
nonpolar covalent bond
the atoms share the electrons equally
polar covalent bond
1 atom is electronegative and the atoms don’t share them equally
ion
2 oppositely charged atoms or molecules
ionic bond
attraction between an anion(neg) and a cation(pos). Ionic compounds formed by these bonds.
hydrogen bond
a hydrogen atom covalent bonded to 1 electronegative atom, also attracted to another electronegative atom. Weak chemical bond.
Van der Waals interactions
this occurs when atoms and molecules are very close together
cohesive force
forces between molecules, this keeps the substance together
adhesive force
forces that attract 1 substance to another
surface tension
a measure of how hard it is to break the surface of a liquid. related to cohesion.
kinetic energy
the energy of motion
thermal energy
a measure of the total amount of kinetic energy
temperature
the avg kinetic energy of molecules
heat
the thermal energy in transfer from 1 body of matter to another
calorie
the amount of heat required to raise the temperature of 1g of water by 1 degree celsius
kilocalories
1cal=1000 cal
joule
a unit of energy
1 J= 0.239 cal
1 cal=4.184 J
specific heat
the amount of heat that must be absorbed or lost for 1g of that substance to change its temp by 1C
water has high specific heat…
keeps temp fluctuations within limits that permits life
heat of vaporization
the heat a liquid must absorb for 1g to be converted to gas
evaporative cooling
the liquid evaporates and its surface remains cool
solution
a liquid that is a homogenous mixture of substances
solvent
the dissolving agent of a solution
solute
the substance that is dissolved
aqueous solution
the water is the solvent
hydration shell
an ion surrounded by a sphere of water molecules
molecular mass
the sum of all masses of all atoms in a molecule
molarity
the number of moles of solute per liter of solution
acid
increases the H+ concentration in water
base
reduces the concentration of H+
pH
-log[H+]
buffers
substances that minimizes changes in concentrations of H+ and OH- solution. Usually contains weak acid and its base.
carbonic acid
a buffer that contributes to pH stability in human blood
ocean acidification
CO2 dissolved in seawater that forms carbonic acid
