| word |
definition |
| element |
a puresubstance that can not be broken chemicaly or phyisacl means |
| compound |
a pure substance coposed of two or more elements that are chemically combined |
| mixture |
a combination of two or more substaces not combined chemically |
| atom |
the smallest particle into which an element can be divided and still retain all of the properteis of that element |
| proton |
the positively charged particles of the nucleus |
| electron |
the negativly charged particles found in the nucleus |
| neutron |
the particles of the nucleus that have no charge |
| periodic law |
a law that states that the chemical and physical properties of elements are periodic functions |
| atomic numbers |
the number of protrons in the nucleus |
| atomic mass |
the weighted average the masses of all naturaly occuring isotopes of an element |
| isotope |
atoms that have the same nuber of protrons but difrent number of nutrons |
| valence electrons |
the electrons in the outermost enrgy level of the atom |
| john dalton |
atom theory |
| JJ Thomson |
small particles in atom |
| ernest rutherford |
positive charged nucleus, atom mostly empty space electrons travel around nucleus |
| niels bohr |
electrons travel in clouds |
| democritus |
1st to come up with idea of atom |
| dmiti mendelev |
father of the periodic table, arrange elements by atomic mass |
| henry moseley |
reaganged periodic table ny atmoic number |
