4.1.1 - Structure of an Atom

Give an approximation for the radius of an atom.

1×10^-10 meters

What are the three subatomic constituents of an atom?

proton, neutron, & electron

Where is most of the mass of an atom concentrated?

In the nucleus.

Approximately what proportion of the total radius of an atom is the radius of the nucleus?

1/10,000

Describe the arrangement of protons, neutrons, and electrons in an atom.

• The protons and neutrons are found in the atom’s nucleus.

• The electrons are found in discrete energy levels around the nucleus.

What type of charge does the nucleus of an atom have? Why?

• Positive charge.

• The nucleus contains protons and neutrons.

• Protons have a positive charge.

• Neutrons have no charge.

Give two ways that an atom’s electron arrangement can be changed.

1. Absorbing electromagnetic radiation.

2. Emitting electromagnetic radiation.

Explain how an atom’s electron arrangement changes when it absorbs EM radiation.

• Electrons move further away from the nucleus.

• They move to a higher energy level.

Explain how an atom’s electron arrangement changes when it emits EM radiation.

• Electrons move closer to the nucleus.

• They move to a lower energy level.

How does the ratio of electrons to protons in an atom result in the atom having no overall charge?

• The number of protons is equal to the number of electrons.

• Protons and electrons have equal and opposite charges, so ch