1. Atomic Structure OVERVIEW
“Normal” Atoms
Ions
Isotopes

2. BUT — We are NOT guessing!
“Unseeable” Atoms
Rutherford Experiment:
RECAP:
What we know about atoms is based on indirect evidence.
So, we really have “models” of atoms that may not be exactly right.
Electron
Nucleus
Hydrogen Spectrum (Bohr):
BUT — We are NOT guessing!

3. “Normal” Atoms Protons Neutrons Electrons
Nucleus
Protons
Neutrons
Electrons
★ Number of protons is constant for each element

4. “Normal” Atoms 7 Li
LITHIUM 3
★ Atomic NUMBER = number of protons

5. “Normal” Atoms
Lithium =
RULE 1: PROTONS DETERMINE IDENTITY !

6. Ions
Protons
Neutrons
Electrons
★ Electrons USUALLY = Protons

7. Ions Protons Neutrons Electrons
★ Electrons can be added or removed to form IONS

8. Ions
Protons
Neutrons
Electrons
RULE 2: ELECTRONS DETERMINE CHEMISTRY!

9. Isotopes Protons Neutrons Electrons
★ Neutrons can vary among atoms of the same element

10. Isotopes Protons Neutrons Electrons
★ Isotopes of an element have different numbers of neutrons

11. Isotopes
★ Atomic MASS = protons + neutrons 7 Li
LITHIUM 3

12. YLDOI: Are You Smarter Than a First Grader?1 st
PART 1: Sally has 11 nickels and dimes in her piggy bank. If 5 of them are nickels, how many dimes does she have?

13. YLDOI: Are You Smarter Than a First Grader?B
BORON 5 11 1 st
PART 2: How many neutrons does boron have?

14. YLDOI: Are You Smarter Than a First Grader?1 st
PART 3: How many neutrons does R.E.D. have?

15. Isotopes Protons Neutrons Electrons
RULE 3: NEUTRONS DETERMINE STABILITY!