1. Atoms
8.5A The student is expected to describe the structure of atoms, including the masses, electrical charges, and locations, of protons and neutrons in the nucleus and electrons in the electron cloud.

2. What is an atom?
An atom is the smallest unit of an element that upholds all of the properties of the element.
This is one atom of helium. This atom has all of the properties of helium.

3. What are the subatomic particles that make up an atom?
Atoms are made up of subatomic particles called protons, neutrons, and electrons.
Proton
Electron
Neutron

4. What are the properties of the nucleus of an atom?
The nucleus is the center part of an atom.
The protons and neutrons are found in the nucleus.
The nucleus has a positive electrical charge.
Most of the mass of an atom is found in the nucleus.
The nucleus has a very small volume.
Nucleus

5. What are the properties of the electron cloud?
Mostly made up of empty space
The area outside of the nucleus of an atom.
Electrons can be found in the electron cloud.
The electron cloud contributes very little mass to the atom.
The electron cloud makes up most of the volume of the atom.
The electron cloud has a negative charge.
Electron Cloud

6. What are the properties of protons?
Protons are located in the nucleus of an atom.
Protons have a positive electrical charge.
Protons have a mass of 1 amu. (amu stands for atomic mass unit, the unit of measurement for the mass of atoms and subatomic particles.)
Proton

7. What are the properties of neutrons?
Neutrons are located in the nucleus of an atom.
Neutrons have no electrical charge, they are neutral.
Neutrons have a mass of 1 amu (they are the same size as protons).
Neutron

8. What are the properties of electrons?
Electrons are located outside of the nucleus in the electron cloud.
Electrons have a negative electrical charge.
Electrons have a mass of 1/2000 amu, much less than neutrons and protons.
Electron

9. By the end of the unit you should be able to:
Identify and describe the nucleus, electron cloud, protons, neutrons, and electrons in an atomic model and describe the properties of protons, neutrons and electrons. You should be able to describe:
The location of the nucleus, electron cloud, protons, neutrons, and electrons.
The electrical charge of the nucleus, electron cloud, protons, neutrons, and electrons.
The mass of the protons, neutrons, and electrons.
Mass and volume of the nucleus and electron cloud.