Scientists came to believe that elements consist of atoms and that compounds are a specific collection of atoms bound together in some way
J.J. Thomson
- Showed in the late 1890s that the atoms of any element can be made to emit tiny negative particles
- All types of atoms must contain these negative particles, which are now called electrons
- Whole atoms are not negatively or positively charged
- The atom must also contain positive particles that balance exactly the negative charge carried by the electrons, giving the atom a zero overall charge
William Thomson
- Thought that an atom might be something like plum pudding
- The atom might be thought of as a uniform "pudding" of positive charge with enough negative electrons scattered within to counterbalance that positive charge
Ernest Rutherford
- His main interest involved alpha particles, positively charge particles with a mass approximately 7500 times that of an electron
- Some alpha particles were deflected by something in the air
- Tested this (metal foil)
- Deflection was caused by the nucleus
- Nucleus has a positive charge to balance the negative charge of the electrons and that is must be small and dense
A proton has the same magnitude of charge as the electron but its charge is positive
A neutron is slightly more massive than a proton but has no charge
J.J. Thomson
- Showed in the late 1890s that the atoms of any element can be made to emit tiny negative particles
- All types of atoms must contain these negative particles, which are now called electrons
- Whole atoms are not negatively or positively charged
- The atom must also contain positive particles that balance exactly the negative charge carried by the electrons, giving the atom a zero overall charge
William Thomson
- Thought that an atom might be something like plum pudding
- The atom might be thought of as a uniform "pudding" of positive charge with enough negative electrons scattered within to counterbalance that positive charge
Ernest Rutherford
- His main interest involved alpha particles, positively charge particles with a mass approximately 7500 times that of an electron
- Some alpha particles were deflected by something in the air
- Tested this (metal foil)
- Deflection was caused by the nucleus
- Nucleus has a positive charge to balance the negative charge of the electrons and that is must be small and dense
A proton has the same magnitude of charge as the electron but its charge is positive
A neutron is slightly more massive than a proton but has no charge