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Description
Flashcards by Fern Bennington, updated more than 1 year ago
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Created by Fern Bennington
almost 8 years ago
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| Question | Answer |
| Democritus 460-370BCE | proposed that matter was made up of particles that cannot be divided futher |
| Aristotle 384-322BCE | proposed elements ware made up of earth, air, wind and fire |
| Robert Boyle 1627-1691 | believed that matter was made up of tint particles that cannot be subdivided- these are made from compounds. solids have fixed particles but liquid and gas have free moving particles. |
| John Dalton 1766-1844 | named particles 'atoms'. believed every atom had its own atomic weight and can react together to from molecules. particles that are identical have the same mass and chemical properties. |
| Eugen Goldstein 1850-1930 | discovered that cathode rays contains negatively charged particles with mass, cathode rays could be split and heavier positive particles |
| Joseph John Thompson 1856-1937 | discovered that atoms have electrons, that they have a very small mass and that they are negatively charged. (plumb pudding model) |
| Ernest Rutherford 1871-1937 | thought that the mass of an atom is not evenly spread and that there is a nucleus and that the nucleus is positively charged and that the electrons circulate the rest of the atom. decided atomic number corresponds to the elements position in the periodic table. |
| Henry Moseley 1888-1915 | along with Ernest Rutherford, decided atomic number corresponds to the elements position in the periodic table. only discovered that half the mass of an atom is made from the proton. |
| James Chadwick 1891-1974 | identified a neutron and that they have no charge but have the same mass as a proton. |
| Niels Bohr 1885-1962 | discovered that electrons orbit the nucleus in energy levels. energy levels have fixed energy values and electrons can only occupy these set values. |
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