study notes for chapter 12 & 13

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