vocab | definitions |
element | a pure substance that can not be broken down by chemical or physical means and cant be put into a simpler substance |
compound | a pure substance composed of 2 or more elements that are chemically combined |
mixture | a combination of 2 or more substances that are not chemically combined |
atom | the smallest particle into which an element can be divided and still retain all of the properties of that element |
proton | the positively charged particles of the nulceus; the # of protons in the nucleusis the atomic # which determines the identity of an element |
electron | the negatively charged particles found in all the atoms; electrons are involved in the formation of chemical bonds |
neutron | the particles of the nucleus that have no charge |
periodic | having a regular repeating pattern |
periodic law | a law that states that the chemical and physical properties of the elements are periodic functions of their atomic #'s |
atomic # | the # pf protons on the nucleus of an atom; the atomic # is the same for all atoms of an element |
atomic mass | the weighted average of the masses of all the naturally occuring isotopes of an element |
isotope | atoms that have the same # of protons but have different #'s of neutrons |
vallence electron | the electrons in the outermost energy level of an atom; these electrons are involved in the forming chemical bonds |
John Dalton | thought up the atomic theory |
J.J. Thomson | thought up the thought of small particles in the atom |
Ernest Rutherford | positive charged nucleus; atom mostly is empty space; electrons travel around nucleus |
Niels Bohr | electrons travel in cluods |
Democritus | 1st to come up with idea of atom |
Demetri Mendeleev | father of the periodic table; arranged the elements by atomic mass |
Henry Mosely | rearranged Periodic tabel by atomic mss |