1. Structure of the Atom
PSC Ch. 3-2

2. The Atom Subatomic particles The nucleus
The notation and the periodic table
Isotopes and Ions
Determining atomic mass

3. Subatomic Particles Electrons Discovered by J.J. Thompson
Discovered how:
Cathode ray tubes-rays traveled from cathode to anode, bent by electric and/or magnetic field, caused paddle wheel to turn
Vital Stats…
Mass: 9 X kg , ~1/2000 mass of p+, u
Charge: -1, -1.30x10-19c,
Location: electron cloud / outside nucleus

4. Subatomic Particles Protons Discovered by J.J. Thompson
Discovered how:
Modified cathode ray tube particles traveled from anode to cathode
Vital Stats:
Mass: X kg; ~2000x mass of e-, 1.007u
Charge: +1, 1.60x10-19c
Location: nucleus

5. Subatomic Particles Neutrons Discovered by James Chadwick
Discovered how:
High energy beam unaffected by magnetic or electric fields
Vital Stats:
Mass: X kg (very similar to the proton)
Charge: 0, neutral
Location: in the nucleus

6. The Nucleus Discovered by Lord Ernest Rutherford Discovered how :
Gold foil experiment- + charged particles shot at thin gold foil. Most went straight through, some deflected. Very few bounced straight back
Small dense + charged core in atom (atom is mostly empty space)
Vital Stats:
+ charge
Dense – over 99% of the atom’s mass
1/trillionth the volume of the atom

7. Graphic Organizer ATOM e- cloud Nucleus -Most of volume -99% of mass
-Very little mass
Nucleus
-99% of mass
-1/trillionth of volume
e - (electrons)
-.0005u
-neg charge, -1
-J.J. Thompson
-cathode ray tube
p+ (protons)
-modified cathode ray tube
-positive charge, +1
-1.007u
no (neutrons)
-James Chadwick
-no charge
-1.009u

8. Isotopes
Sometimes atoms of the same elements have a different number of neutrons
All elements have isotopes!
And they exist in different abundances.

9. Ions (p. 161) Sometimes atoms will gain or lose electrons
Too many : negative charge
Too few: positive charge