law of conservation of mass
law stating energy is neither created nor destroyed in chemical reaction
law of definite proportions
law stating all samples of given compound have same proportions of constituent elements
law of multiple proportions
law stating that when 2 elements (A and B) from 2 different compounds, masses of element B that combine w/ 1g of element of A can be expressed as a ratio of smaller whole #s
atomic theory
theory that each element is composed of tiny indestructible particles called atoms; all atoms of a given element have same mass and other properties; atoms combine in simple, whole # ratios to form compounds
cathode rays
electrode in an electrochemical cell where reduction occurs; electrons flow toward cathode
cathode ray tube
stream of electrons produced when a high electrical voltage is applied between 2 electrodes within a partially evacuated
electrical charge
fundamental property of certain particles that causes them to experience force in presence of electric fields
electron
negatively charges, low mass particle on outside of nucleus of all atoms that occupies most of atom's volume but contributes almost none of its mass
radioactivity
state of those unstable atoms that emit subatomic particles or high-energy electromagnetic radiation
nuclear theory
theory that most of atom's mass and all positive charge is contributed in small, dense nucleus
nucleus
very small, dense core of atom that contains most of atom's mass and all of positive charge; composed of protons and neutrons
protons
positively charged subatomic particle found in nucleus of an atom
neutrons
electrically neutral subatomic particle found in nucleus of an atom, w/ mass almost equal to that of proton
atomic mass unit (amu)
unit used to express masses of atoms and molecule particles, defined as 1/12 mass of carbon atom containing 6 protons and 6 neutrons
atomic number
# of protons in an atom; defines element
chemical symbol
1 or 2 letter abbreviation for element listed directly below atomic # on periodic table
isotopes
atoms of some element w/ same # of protons but different # of neutrons and consequently different masses
natural abundance
relative % of particular isotope in naturally occurring sample w/ respect to other isotopes of same element
mass number
sum of # of protons and neutrons in an atom
ions
atom or molecule w/ net charge caused by loss or gain of electrons
cations
positively charged ions
anions
negatively charged ions
periodic law
law based on observation that when elements are arranged in order of increasing mass, certain sets of properties recur periodically
metals
large class of elements that are generally good conductors of heat and electricity, malleable, ductile, lustrous and tend to lose electrons during chemical changes
nonmetals
class of elements, tend to be poor conductors of heat and electricity and usually gain electrons during chemical reactions
metalloids
category of elements found on boundary between metals and nonmetals of periodic table, w/ properties intermediate between those of both groups; semimetals
semiconductors
material w/ intermediate electrical conductivity that can be changed and controlled
main-group elements
elements found in s or p blocks of the periodic table whose properties tend to be predictable based on position in table
transition metals/elements
elements in d block of periodic table whose properties tend to be less predictable based simply on position in table
family/group
columns within main group elements in periodic table that contain elements that exhibit similar chemical properties
noble gases
group 8a elements, largely nonreactive (inert) due to their stable filled p orbitals
alkali metals
highly reactive metals in group 1a of periodic table
alkaline earth metals
fairly reactive metals in group 2a of periodic table
halogens
highly reactive nonmetals in group 7a of periodic table
atomic mass
average mass in amu of atoms of a particular element based on relative abundance of various isotopes; numerically equivalent to mass in grams of 1 mole of element
mass spectrometry
experimental method of determining precise mass and relative abundance of isotopes in given sample using instrument called mass spectrometer
mole
a unit defined as the amount of material containing 6.0221421 * 10�� particles
Avogadro's number
# of ��C atoms in nexactly 12g of ��C; equal to 6.0221421 * 10��
molar mass
mass in grams of 1 mole of atoms of element; numerically equivalent to atomic mass of element in amu