1. November 14, 2012 8th Grade Physical Science Ms. McKinley
What is an Atom? C-Notes
November 14, 2012
8th Grade Physical Science
Ms. McKinley

2. Let’s Brainstorm…
Make a list of items that have a center and an outside that are made of different materials.

3. What did we come up with??

4. What is an Atom? The smallest particle of an element
The basic building blocks of matter
The arrangement and types of atoms give matter its properties.
Atoms are like legos! They are building blocks

5. What is an Atom? (cont’d)
2000 years ago the Greeks defined atoms as the smallest parts of matter.
Greek word “atomos” means uncuttable

6. The Structure of an Atom
Two major components:
The NUCLEUS
The ELECTRON CLOUD
3 basic subatomic particles (“subatomic” means smaller than an atom):
Protons
Neutrons
Electrons
Could we add atoms to our brainstorming list??

7. Subatomic Particles Most of the atom’s mass. ATOM NUCLEUS ELECTRONS
POSITIVE
CHARGE
PROTONS
NEUTRAL
NEUTRONS
NUCLEUS
NEGATIVE CHARGE
ELECTRONS
ATOM
ATOM
NUCLEUS
ELECTRON CLOUD
ELECTRONS
PROTONS
NEUTRONS
POSITIVE CHARGE
(+)
NEUTRAL CHARGE (0)
NEGATIVE CHARGE
(-)
Most of the atom’s mass.

8. The Nucleus Protons and Neutrons combine to make the nucleus
Held in place by the Strong Force

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10. The electron cloud
Electrons (-) move around the outside of the nucleus.
The ‘cloud’ has different layers called RINGS, SHELLS, or ORBITALS.
Each ring holds a specific # of electrons

11. Atoms and the Periodic Table
Scientists use the Bohr model to represent an atom.
Electrons: (-) negative charge
Protons: (+) positive charge e P n
Neutrons: (=) neutral charge

12. Bohr Model
Proton
Orbit
Neutron
Electron