| A | B |
|---|
| who was the first person to suggest the existence of atoms? | Democritus |
| Daltons atomic theory is? | 1. all elemens are composed of tiny indivisible particles called atoms.2 atoms of the same element are identical. the atoms of any one element are different from those of any other element.3 atoms of different elements can physically mix together or can chemically combine with one another in simple who-number ratios to form compounds.4 chemical reactions occur when atoms are separated, joined, or rearranged. atoms of one element, however, are never changed into atoms of another element as a result of a chemical reaction |
| atom is? | smallest particle of an element that retians the properties of that element. now they can be broken even smaller by using atom smashers |
| electrons are? | negatively charged subtomic particles |
| cathode ray is? | Thomson discovered electron and did an expiriment. an electrode(anode) comes positivly charged and the other electrode(cathode) comes negatively charged. a glowing beam is formed between electrodes. the beam |
| whats in a cathode ray? | a stream of tiny negatively charged particles moving fast |
| Robert A. Millikan is who? | american scientist who found the quantity of charge carried by and electron |
| what is the lightest atom? | hydrogen atom |
| what did E. Goldstein find? | he found canal rays which are rays going in the opposite direction of cathode rays |
| protons are? | positively charged subatomic particles |
| what did James Chadwick find? | neutrons |
| neutrons are? | subatomic particles with no charge but with a mass nearly equal to that of a proton |
| what did Ernest Rutherford find? | directed a beam of alpha particles at a very thin sheet of gold foil. alpha particles should pass easly through gold w/ only a slight deflection cuz of the positive charge thought to be spread out in the gold atoms |
| What was Rutherford's new theory? | that atoms have a neucleus |
| neucleaus is? | central core of an atom composed of protons and neutrons |
| atomic # is? | number of protons in the neucleus of an atom of that element |
| atoms are... | ...electrically neutral(# of electrons must=#of protons in neucleus |
| mass # is? | total # of protons and neutrons in an atom |
| how do u find number of neutrons in an atom? | mass number minus atomic number |
| isotopes are? | atoms that have same number of protons but different number of neutrons(same number of protons and electrons) |
| atomic mass unit(amu) is? | defined as 1/12 the mass of a carbon-12 atom |
