CHAPTER 5: ATOMIC THEORY:
The Nuclear Model of the Atom
1-2, 9, 13, 15, 17, 19, 21, 25, 27, 29, 31, 34, 35, 37, 39, 43, 45
DALTON’S ATOMIC THEORY
1. An element is composed of tiny, indivisible* particles called atoms.
2. All atoms of an element are identical* and have the same properties.
3. Atoms of one element will differ from atoms of another element.
4. Compounds contain atoms in small whole number ratios.
e.g., each water molecule (H
O) has one O atom and 2 H atoms
5. Atoms can combine to form different compounds.
e.g., carbon and oxygen can combine to form CO
* Later proven wrong
Michael Faraday, William Crookes, and many other scientists carried out experiments
J.J. Thomson was given credit for discovering electron although evidence had accumulated for
20 years before his group’s determination of the electron’s charge and mass.
Eugen Goldstein (late 1880s)
– carried out experiments on canal rays and found they consisted of
And decades later, James Chadwick won the Nobel Prize winner for his discovery (1935)
= neutral subatomic particle
Atoms are made up of subatomic particles:
negatively charged subatomic particle (charge = –1)
positively charged subatomic particle (charge = +1)
neutron (n) =
subatomic particle (charge=0)
Charge Relative Mass
1/1836 ≈ 0