history of atom

Question 1

Democritus (400 b.c.)

Answer 1

atoms are made of a single material that is formed into different shapes and sizes. “atomos “ means “not to be cut” which refers to the smallest piece of matter.

Question 2

Aristotle (332 B.C.)

Answer 2

All matter is made up of four elements; fire, air, water, and earth. Matter has four properties: hot, cold, dry, and wet.

Question 3

Dalton (1807)

Answer 3

Atoms of the same element are exactly alike. Atoms of different elements are different. Atoms are made of a single material that is formed into different shapes and sizes. Atoms are “uncuttable”

Question 4

Thomson (1903)

Answer 4

There are small, negatively charged particles inside an atom called electrons. This theory led to the “Plum pudding” model, in which negative particles are stuck in a positively charged substance.

Question 5

Rutherford (1911)

Answer 5

Atoms contain mostly empty space. Most of an atom’s mass is in the nucleus. There is a small, dense, positively charged nucleus.