Question | Answer |
Aufbau Principle | the rule that electrons must occupy orbitals of lowest energy first |
Pauli Exclusion Principle | an atomic orbital can hold only 2 electrons and they must have opposite spins |
Hund's Rule | electrons must fill one in each orbital before they pair up |
Dmitri Mendeleev | arranged the elements in a table by increasing atomic mass and in columns by oxygen combination |
John Newlands | put elements in a pattern in which every 8th element repeated a characteristic |
Lothar Meyer | was working on a periodic table of elements but he was unsuccessful because he couldn't explain how it could be used |
J.W. Dobereiner | placed elements into groups of three by similar characteristics |
Henry Moseley | assigned every element an atomic number that allowed for the modern arrangement of the periodic table |
Glenn Seaborg | placed the inner transitionals at the bottom of the table |
Democritus | named the atom from the word "atomos" |
J.J. Thomson | discovered the electron using a cathode ray tube |
J.J. Thomson | had the original idea of how the electrons were placed in the atom similar to raisins in pudding |
Ernest Rutherford | discovered that the atom had a central core that was relatively small in volume but large in mass called the nucleus |
Ernest Rutherford | used gold foil and alpha particles in his famous discovery |
James Chadwick | discovered the neutron |
John Dalton | formulated the atomic theory with originally 4 parts that later 2 were disproved |
indivisible and identical | the two parts of the original atomic theory that were rejected with the discovery of subatomic particles |
isotopes | different forms of the same element that have different number of neutrons |
oxidation number | the "charge" that an atom aquires when it looses or gains electrons |
chemical label color blue | used for health precautions |
chemical label color red | used for flammability precautions |
chemical label color yellow | used for reactivity precautions |
MSDS | material safety data sheets; required for every chemical on hand in a lab |
Goggles must be worn in these 3 circumstances | using heat, chemicals or glassware |
period | a horizontal row on the periodic table; there are 7 |
group/family | a vertical column on the periodic table; there are 18 |
halogens | special name of group 17 |
noble gases | special name of group 18 |
alkali earth metals | special name of group 2 |
alkali metals | special name of group 1 |
radioactive elements | have their mass in parenthesis |
synthetic elements | all elements past Uranium and Tc |
inner transitional elements | also called Rare Earth Elements |
Lanthanides | elements with atomic numbers 57-71 |
Actinides | elements with atomic numbers 89-103 |
representative elements | elements with electrons in the S or P energy levels; also called the "main group" elements |
metalloids | these elements border the "stair-step"; there are 8 of them |
elements that are liquid at room temperature | Bromine and Mercury |
number of elements that are gases at room temperature | eleven |
solution | another name for a homogeneous mixture |
homogeneous mixture | physically combined matter that has consistent composition |
heterogeneous mixture | physically combined matter that does not have consistent composition |
accuracy | this is a measure of how "close" a measurement is to the actual value |
precision | this is a measure of how "consistent" measurements are with each other |
Niels Bohr | had the idea that electrons moved in fixed paths or orbits |
s sublevel holds how many electrons and has how many orbitals | 2/1 |
p sublevel holds how many electrons and has how many orbitals | 6/3 |
d sublevel holds how many electrons and has how many orbitals | 10/5 |
f sublevel holds how many electrons and has how many orbitals | 14/7 |
valence | the "outer" or highest occupied energy level |
electronegativity | how well an element attracts electrons to itself |
ionization energy | the energy needed to make an element lose an electron |
atomic radius | half the distance between the nuclei of two atoms of the same element when the atoms are joined |
ion | charged form of an atom of an element with less or more electrons than neutral |
highest occupied energy level | equal to the period of the element |
Avogadro's number | equal to a mole of representative particles; 6.02 x 10 23 |
mole | equal to Avogadro's number of representative particles |