If we made a scale model of an atom and wanted to use Cowboy Stadium as our electron
cloud, the nucleus of the atom would be the size of the eraser on the end of your pencil. An
electron would still be smaller than the point on a straight pin.
WHAT DO THESE BOXES MEAN??
Number of protons/ Atomic Number
All atoms of the same element have the same
number of
protons
Number of Protons, Neutrons, & Electrons
- =
Mass Number
How to Use the Periodic Table
p+
e- n0
# Protons =
# Electrons =
# Neutrons =
Example 1: Argon
EXAMPLE PROBLEM
•Write the nuclear notation for the chemical element that has 6 protons and 8 neutrons
#1•Write the Nuclear notation for the chemical element that has 17 protons and 16 neutrons (in your table)
Cl or Chlorine-3317
33
#2How many protons are in the isotope 54Cr? (Chromium-54) (add it to your table)
24 (like every atom of Chromium)
#4How many electrons are in the isotope 23Na? Write it’s nuclear notation (add to table)
11 electrons
AVERAGE MASS OF SUBATOMIC PARTICLES
Subatomic Particle
Electric Charge
Mass Number (amu)
Location
Electron -1 0 Electron cloud
Proton +1 1 Nucleus
Neutron 0 1 Nucleus
Atomic Mass Unit 1 amu = 1.66 x 10-
24 g
EXAMPLE
+# p+ Mass of p+
x
Protons
# n0 Mass of n0
x
Neutrons
# e-Mass of e-
x
Electrons
+ = + + =
Example 7: Mass of Beryllium
4 Protons4 Electrons5 Neutrons
GALLERY WALK
• Walk around to the different pictures of isotopes• Identify which isotope it is and fill out the
information in your packet• Figure out – WHAT IS THE DIFFERENCE?
ATOMS OF THE SAME ELEMENT WITH DIFFERENT NUMBERS OF NEUTRONS
(THEREFORE HAVE DIFFERENT MASSES).
Isotopes
FOUR ISOTOPES OF HELIUM
1.What sub-atomic particle(s) are the same for the isotopes of Helium?
2.What sub-atomic particle(s) are different for the isotopes of Helium?
3.Are these four isotopes neutral? Why or Why not?
WORKOUT!
Write the following as an isotope symbol…
4. Copper-63 5. Copper-64 6. Lithium-7 7. Lithium-6