Front

What is an element?

Back

An element is a pure substance that cannot be broken down into simpler substances by chemical means. It consists of atoms that all have the same number of protons.

Front

What is the atomic number of an element?

Back

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

Front

What are the three main subatomic particles?

Back

The three main subatomic particles are protons, neutrons, and electrons.

Front

What is the charge of a proton?

Back

A proton has a positive charge.

Front

What is the charge of an electron?

Back

An electron has a negative charge.

Front

What is the charge of a neutron?

Back

A neutron has no charge (it is neutral).

Front

What is the nucleus of an atom?

Back

The nucleus is the central part of an atom that contains protons and neutrons.

Front

Who discovered the electron?

Back

Joseph Thomson discovered the electron using the cathode ray tube experiment.

Front

Who is known for the nuclear model of the atom?

Back

Ernest Rutherford is known for the nuclear model of the atom, which describes the atom as having a dense nucleus surrounded by electrons.

Front

What is the mass number of an atom?

Back

The mass number is the total number of protons and neutrons in the nucleus of an atom.