Chapter 9-Lesson 1

Smallest piece of an element that still represents that element.

An atomic particle with one negative charge.

Developed the model of the atom in which the electrons orbit the nucleus in energy levels.

There are 6 types of quarks.

An electron cloud is mostly empty space.

English schoolteacher who proposed the atomic theory of matter.

Who devised the "plum pudding model" in atomic theory?

These make up protons and neutrons.

An atomic particle that has one positive charge.

The neutral particle in the nucleus of an atom.

Atoms have no charge because the positive and negative charges are balanced.

The number of protons in an atom of an element.

Who performed experiments showing that most of an atom's mass is concentrated in its center?

An area around an atomic nucleus where an electron is most likely to be located.

Greek philosopher who made a mental model of the atom.

Thomson thought that the atom was made mostly of negatively charged material.

Area in the center of the atom where most of an atom's mass and (+) charge is concentrated.

Who discovered the neutron?