1. Atoms and Isotopes

2. The Atom
An atom is the smallest part of the element that still retains the properties of the atom.
A crumb of the cake
An element is matter made up of only one type of element.

3. Atomic Structure Protons Neutrons Electrons
Positive, inside the nucleus, same size as a neutron p+
Neutrons
Neutral, inside the nucleus, same size as a proton no
Electrons
Negative, outside the nucleus, much smaller e-
Proton, neutron, electron

4. Mass and Atomic Numbers
Atomic number = number of protons (#p+)
Mass number = number of protons + number of neutrons (#p+ + #no)
In a neutral atom # positives = # negatives
#p+ = #e-
Practice
How many protons, neutrons, and electrons are in an atom of carbon-12? (what does the 12 represent here?)
Mass number and atomic number

5. Isotopes
Isotopes are atoms of the same element that have different mass numbers.
For example chlorine-35 and chlorine-37.
How many protons does Cl-35 have? Cl-37?
How many electrons do each have?
How many neutrons do each have?
What is the difference between the isotopes?
isotopes

6. Compare and Contrast
Iron - 55
Iron - 56
practice

7. Comparison Matrix Characteristics Charge Size Location proton
items to be compared
Charge
Size
Location
proton
similarities
differences
electron
neutron

8. Independent Practice Finish Comparison Matrix
Atoms and Their IsotopesWorksheet