1. 2018 SSNI Atomic Fundamentals Marissa Reigel
A discussion and activities about the building blocks of matter.

2. Matter Term that describes all of the physical substances around us
your table
your body
your pen or pencil
Everything!
Anything that
has mass and
takes up space (has volume)
Matter is made up of different kinds of atoms

3. Models…
In the case of atoms, scientists use large models to explain something that is very small
Models of the atom are used to explain data or facts that were gathered experimentally
Models are theories
Often used for things that are too
small to be observed
large to be observed
difficult to be understood easily

4. Early Models of the Atom…
John Dalton
All elements are composed of indivisible particles (atoms)
Atoms of the same element are the same
Atoms of different elements are different
Compounds consisted of atoms of different elements combined together
Element A atom
Element B atom
Element C atom
Compound with
elements A, B, & C

5. Early Models of the Atom…
JJ Thomson
Plum pudding model
Atom is
Made of a positively charged material (pudding or soup)
With the negatively charged electrons scattered through it

6. Early Models of the Atom…
Ernst Rutherford
Mostly empty space
Small, positive nucleus
Contained protons
Negative electrons scattered around the outside (“cloud”)
Planetary model

7. Early Models of the Atom…P E
Niels Bohr
Electrons have certain classical motions
Electrons orbit around the nucleus at discrete distances (shell structure)
Nucleus (sun) is composed of protons and neutrons
Attraction due to electrostatic forces

8. Atomic Structure
Nucleus
Protons
Neutrons
Electrons
Space

9. Atomic Structure
If an atom could be enlarged to the size of a football stadium…
The nucleus (protons and neutrons) would be the size of a grape or a marble at midfield
Orbiting electrons would be size of salt grains swirling around the upper deck

10. Atomic Structure – Bohr’s model based on results of Gold Foil Experiment

11. Atomic Structure – Bohr’s model based on results of Gold Foil Experiment
(Zinc Sulphide)

12. Activity: What’s Inside the Atom?
Roll marble
Determine the geometric
shape underneath

13. Atomic Structure… Electrons
Tiny, very light particles (negligible mass)
Have a negative electrical charge (-)
Move around the outside of the nucleus

14. Atomic Structure… Protons Number of protons = atomic number
Much larger and heavier than electrons
Have a mass of 1 AMU
Protons have a positive charge (+)
Located in the nucleus of the atom
Atoms with same number of protons are the same element
Number of protons = atomic number

15. Atomic Structure… Neutrons
Large and heavy like protons
Have a mass of 1 AMU
Neutrons have no electrical charge
Located in the nucleus of the atom
Neutralize repulsive force of positive protons
Acts as a “glue” that keeps protons in the nucleus
Number of protons + number of neutrons = atomic mass