Front

What is an atomic number?

Back

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

Front

How many protons does an element with an atomic number of 9 have?

Back

9

Front

What charge do protons carry?

Back

Protons carry a positive charge.

Front

What charge do neutrons carry?

Back

Neutrons have no charge.

Front

Where is most of the mass of an atom located?

Back

Most of the mass of an atom is located in the nucleus.

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.

Front

If an atom has 20 neutrons and a mass number of 39, how many protons does it have?

Back

19 (Mass number = Protons + Neutrons; 39 = Protons + 20).

Front

What is the relationship between atomic number and the number of electrons in a neutral atom?

Back

In a neutral atom, the number of electrons equals the atomic number.

Front

What is the role of electrons in an atom?

Back

Electrons are negatively charged particles that orbit the nucleus and are involved in chemical bonding.

Front

What is the difference between an atom and an ion?

Back

An atom is neutral, while an ion has a net charge due to the loss or gain of electrons.