Subatomic Particles

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 electrons does an atom have if its atomic number is 9?

Back

9 electrons, as the number of electrons equals the atomic number in a neutral atom.

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

Back

19 protons, since mass number = protons + neutrons (39 = protons + 20).

Front

What charge do protons carry?

Back

Protons carry a positive charge.

Front

What is the relationship between protons and the atomic number?

Back

The atomic number is equal to the number of protons in an atom.

Front

How many protons does Boron (B) have?

Back

Boron has 5 protons.

Front

What is the charge of neutrons?

Back

Neutrons have no charge (neutral).

Front

What is the mass of a proton compared to a neutron?

Back

A proton and a neutron have approximately the same mass, about 1 atomic mass unit (amu).

Front

What is the significance of the atomic mass unit (amu)?

Back

The atomic mass unit (amu) is a standard unit of mass that quantifies mass on an atomic or molecular scale.