Word | Definition |
Element | A pure substance that cannot be seperated or broken down into simpler substances by physical or chemical means |
Compound | a pure substance composed of two or more elements that are chemically combined |
Minture | a combination of two 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 positivley charged perticles of the nucleus the number of protons in a nucleus is the atomic number, which determines the identy of an element |
electron | the negativley charged perticles found in all atoms; electons are involved in the formation of chemical bonds |
neutron | the perticles 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 elements are periodic functions of their atomic numbers |
atomic number | the number of protons in the nucleus of an atom; the atomic number is the same for all atoms of an element |
atomic mass | the weighted average of the masses of all the naturally occurring isotopes of an element |
isotope | atoms that have the same number of protons ut have different numbers of neutrons |
valence electron | the electrons in the outermost enerty leven of an atom; thses electrons are involved in forming chemical bonds |
John Dalton | Atomic Theory |
J.J. Thomson | small perticles in an atom |
Ernest Rutherfor | positive charged nucleus. atom mostly empty space electrons travel around nucleus |
Niels Bohr | electons travel in clouds |
Democritus | 1st to come up wth the idea of atom |
Dmitri Mendeleev | Father of Periodic Table, arrange elements by atomic mass |
Henry Moseley | rearranged periodic table by atomic number |