Radioactivity

Radioactivity

• BrainPop
• Atomic Model

• A charge can be either positive or negative.
• Like charges repel
• Two positive charges try to push each other apart
• unlike charges attract
• Ex. A positive charge draws closer to a negative charge
• art.

• Protons are positive charges
• Electrons are negative charges
• A proton and an electron will be attracted to each other
• Neutrons don’t have any charge so they won’t be attracted or repelled by anything else

• The nucleus of an atom contains protons and neutrons
• But protons repel each other!
• The closer together they are, the greater the force that wants to push them apart

• Protons and neutrons are also called nucleons
• A proton is a nucleon
• A neutron is a nucleon

Check Your Understanding

• An atomic nucleus has 20 protons and 25 neutrons. How many nucleons does it have?
• Protons + Neutrons = Nucleons
• 20 + 25 = 45
• A nucleus has 10 protons and 12 neutrons. How many nucleons does it have?

Protons + Neutrons = Nucleons

• Protons + Neutrons = Nucleons
• 40 + 50 =
• + 51 = 91
• 100 + = 257
• + 83 = 139
• BrainPop Atoms

Strong Nuclear Force

• The atom does not fall apart when 2 or more positive charges are extremely close together, so there has to be another force acting,
• Physicists call this force the Strong nuclear force.

The Atomic Nucleus

• Nucleon: The principal building block of an atomic nucleus
• The nucleus of an atom is composed of nucleons
• Ex: protons and neutrons
• The mass of protons and neutrons are nearly the same

The number of protons determines the properties of an atom (i.e. what type of atom it is)

• The number of protons determines the properties of an atom (i.e. what type of atom it is)
• Carbon always has 6 protons, hydrogen always has 1 proton, oxygen always has 8 protons
• You change the # of protons, you change the type of atom
• Neutrons have no affect on an atom’s properties