42 terms

Chem 105

the result of a natural change of an isotope of one element into an isotope of a different element
alpha rays
stream of positively charged particles (alpha particles) they have a +2 charge and a mass of 4 amu
beta rays
composed of a stream of negatively charged particles (beta particles) that have properties similar to an electron
gamma rays
consists of electromagnetic radiation of very short wavelengths (high frequency and high energy) most dammaging of radioactive particles
nuclear reaction
results from radioactivity
protons and neutrons
alpha emitters
atoms that undergo radioactive decay resulting in the release of an alpha particle
beta emitters
nuclei of atoms that undergo emission of beta particles
gamma rays
highly energetic photons (excess energy released from an alpha or beta particle)
particle equal in mass but opposite of charge to an electron (emission = decrease of atomic number by one)
stable isotope
does not spontaneously decompose into a different element
1. most stable when the number of neutrons is equal to or greater than the number of protons with exception to H-1 and He-3
2. elements with low atomic numbers, the number of neutrons is almost equal to the number of protons
3. nuclear stability is greater for isotopes that contain even numbers of protons and neutrons
half life
the period of the time required for exactly one half of the number of atoms in the original sample to undergo a radioactive decay, forming a new element
splitting of heavy nuclei into smaller nuclei releasing large amounts of energy in the process
energy releasing combination of light nuclei forming heavier ones
critical mass
the size of a sample that is large enough to self-sustain a chain reaction
forms when atoms are stripped of their electrons, which results in positively charged nuclei
octet rule
a noble gas electron configuration
lewis dot symbols
determining direction of electron transfer
electrostatic forces
forces between particles caused by their differences in electric charges (ionic bond) --> form and ionic compound
crystal lattice
the attraction of oppositely charged ions allows them to settle into this structure
neutral ionic compounds formed from metal ions (cations) and nonmetal ions (anions)
chemical nomenclature
the system that scientists use for naming ionic and molecular compounds
binary compounds
ionic compounds consisting of two atoms
covalent bond
atoms share some or all their valence electrons in such a manner as to achieve a noble gas configuration
molecular formula
used when referring to covalently bonded compounds
double bond
results when two atoms share four electrons
triple bond
forms when six electrons are shared between two atoms
bond energy
the energy to break bonds between a specific pair of atoms
the ability of an atom during bond formation to attract electrons from its bonding partner
polar covalent bond
electrons are not shared equally
strength of a polar bond (based on the differences in electronegativities of the atoms involved in bonding
valence shell electron pair repulsion theory
(VSEPR) the groups of electrons arrange themselves about the central atom in such a way that lowers the molecules overall energy
central atom
the atom in a molecule to which all other atoms are bonded
electron pair shape
this includes the unbonded electron pair connected to the central atom
1. linear (180)
2. trigonal planar (120)
3. tetrahedral (109.5)
molecular shape
ignoring the unbonded electron pair connected to the central atom
compounds that conduct electricity when melted or dissolved in water
intermolecular forces
attractions between individual molecules
dipole dipole forces
forces between polar molecules
hydrogen bonding
result of the strong interaction between a hydrogen atom and N, O, or F
fixed shape and volume, non compressible
variable shape, fixed volume, non-compressible
variable shape and volume, easily compressed