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chapter 4 chemistry
| Term | Definition | EXAMPLES |
|---|---|---|
| dalton's atomic theory | dalton formulated hypotheses and theories to explain his observation--- elements are made of atoms, they can combine together to make compounds, atoms of the same element are the same, you need chemical reactions to seperate compounds | water is made of hydrogen and oxygen |
| electron | negatively charged subatomic particles on the outside | discovered by JJ Thompson in 1897 |
| cathode ray | glowing beam | how he discovered the electron |
| proton | positively charged subatomic particles | discovered by goldstein |
| neutron | subatomic particles with no charge but with a mass nearly equal to that of a proton | discovered by Chadwick |
| nucleus | tiny central core of an atom and is composed of protons and neutrons | majority of the mass ,discovered by Rutherford |
| atomic number | number of protons in the nucleus of an atom of that element | oxygen--- atomic # 8--- |
| mass number | the total number of protons and neutrons in an atom | hydrogen-1- number at the end is mass number |
| isotopes | atoms that have the same number of protons but different numbers of neutrons | 1+2=3 |
| atomic mass unit (amu) | defined as one twelfth of the mass of a carbon-12 atom | the decimal points numbers |
| atomic mass | weighted AVERAGE mass of the atom in a naturally occurring sample of the element | THE AVERAGE MASS |
| atom | smallest particle of an element that retains its identity in a chemical reaction | hydrogen--- hydrogen atoms, oxygen----oxygen atoms |
Created by:
candye12