Atomic Theory History Unit 02 Flashcard

Front

What did J.J. Thomson conclude from his experiments?

Back

Atoms contain tiny negatively charged particles called electrons.

Front

What was Niels Bohr's contribution to atomic theory?

Back

Electrons move around a nucleus in prescribed orbits.

Front

In what year did John Dalton propose his atomic theory?

Back

1803.

Front

What are the main postulates of John Dalton's atomic theory?

Back

1. Elements are made of atoms. 2. Atoms of a given element are identical. 3. Atoms cannot be subdivided, created, nor destroyed.

Front

What did Ernest Rutherford discover about the atom?

Back

The atom has a small, dense nucleus that contains protons.

Front

What is the significance of the atomic number?

Back

The atomic number is the number of protons in an atom's nucleus and determines the element's identity.

Front

What did the gold foil experiment demonstrate?

Back

Most of the atom is empty space, with a small, dense nucleus.

Front

Who proposed the planetary model of the atom?

Back

Niels Bohr.

Front

What is the difference between an atom and a molecule?

Back

An atom is the smallest unit of an element, while a molecule is a group of two or more atoms bonded together.

Front

What is the charge of an electron?

Back

Electrons have a negative charge.