Atomic Number and Mass Number

Front

What is the 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 is the atomic number related to electrons in a neutral atom?

Back

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

Front

What is the mass number?

Back

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

Front

How do you calculate the number of neutrons in an atom?

Back

Number of neutrons = Mass number - Atomic number.

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 (neutral).

Front

What is the charge of an electron?

Back

An electron has a negative charge.

Front

What do all atoms of the same element have in common?

Back

All atoms of the same element have the same number of protons.

Front

What is an isotope?

Back

Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons.

Front

How does the atomic number determine the position of an element in the periodic table?

Back

Elements are arranged in the periodic table in order of increasing atomic number.