Name: _________________________________ Date: __________ Class: _______
John Dalton (1766 – 1844):
John Dalton was an English chemist. His ideas form the atomic theory
of matter. Here are his ideas.
All elements are composed (made up) of atoms. It is impossible
to divide or destroy an atom.
All atoms of the same elements are alike. (One atom of oxygen
is like another atom of oxygen.)
Atoms of different elements are different. (An atom of oxygen is different from an atom of hydrogen.)
Atoms of different elements combine to form a compound. These atoms have to be in definite whole number ratios.
For example, water is a compound made up of 2 atoms of hydrogen and 1 atom of oxygen (a ratio of 2:1). Three atoms
of hydrogen and 2 atoms of oxygen cannot combine to make water.
1. What is the name of John Dalton’s theory? THE ATOMIC THEORY OF MATTER
2. What are elements made of? ELEMENTS ARE MADE OF ATOMS
3. An atom of hydrogen and an atom of carbon are DIFFERENT
4. What are compounds made of? COMPOUNDS ARE MADE OF ATOMS OF TWO OR MORE DIFFERENT ELEMENTS
5. The ratio of atoms in HCl is: a) 1:3 b) 2:1 c) 1:1
6. The ratio of atoms in H2O is: a) 1:3 b) 2:1 c) 1:1 2 atoms of hydrogen and 1 atom of oxygen
