- Created by: ambermason0608
- Created on: 31-10-18 09:30
These particles can be deflected by magnets or charge
These particles must be negatively charged
Thompson called them electrons
Cathode Ray Tube
“I did an experiment that proved the plum pudding idea was wrong. I called it the ‘scattering experiment”
In the 20th Century the work of Thompson, Millikan, Rutherford and Chadwick led to an understanding of the structure of atoms and the existence of subatomic particles.
Rutherford's Atomic Model
Rutherford’s atom model:
Electron- negative, mass nearly nothing
Nucleus= positively charged (can deflect alpha particles)
Most of the mass concentrated in the nucleus
Most alpha particles passed straight through the atom, so most of the atom is empty
Elements are chemicals that can’t be broken down into simpler substances. They are building blocks to make other chemicals. Scientists wanted to know how each of the elements were related to each other so that they could understand the rules of how new chemicals could be made.
Mendeleev grouped elements according to their properties and mass to make the periodic table. He used his table to predict the existence of undiscovered elements.
It is possible for the nuclei of the same element to have different numbers of neutrons in the nucleus (but it must have the same number of protons).
Three types of Hydrogen (istopes)
Daltons Atomic theory
Dalton's Atomic Theory (1808)
- All matter is composed of atoms. Atoms are indivisible and indestructible I.E. Democritus’ idea (no knowledge of protons, neutrons, electrons, quarks etc.)
- All atoms of given elements have the same mass (no knowledge of isotopes)
- Atoms combine to form compounds in simple whole-number ratios
- An atom of one element cannot change into an atom of another element- chemical reactions only involve rearrangement of atoms
Discovery of Ions
Discovery of Ions:
In 1830, Faraday observed that substances can move when an electric field is placed over the water. He called these substances ‘ions’ (greek for wanderer). In 1884, Arrhenius reasoned that ions are atoms that carry charge.