Atomic Number and Mass Number

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

How is the mass number of an atom calculated?

Back

The mass number is calculated by adding the number of protons and neutrons in the nucleus.

Front

What is the charge of a proton?

Back

A proton has a positive charge.

Front

What is the charge of a neutron?

Back

A neutron has no charge (it is neutral).

Front

What is the charge of an electron?

Back

An electron has a negative charge.

Front

How many electrons are in a neutral atom?

Back

In a neutral atom, the number of electrons is equal to the number of protons.

Front

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

Back

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

Front

What is the mass number of a Magnesium atom with 12 protons and 12 neutrons?

Back

The mass number is 24 (12 protons + 12 neutrons).

Front

If an atom has an atomic number of 3, how many protons does it have?

Back

It has 3 protons.

Front

How many neutrons does a sodium atom with a mass number of 23 have?

Back

It has 12 neutrons (23 mass number - 11 protons = 12 neutrons).