1. MATTER & ATOMS…

2. WHAT IS MATTER?
Matter describes all of the physical substances around us: your table, your body, a pencil, water, air or all solids liquids & gasses.
Anything that has mass and volume (takes up space)
Made up of different kinds of atoms

3. The BIG Idea???
Matter is made of ATOMS!!!

4. Why use MODELS for ATOMS?
In the case of atoms, scientists use large models to explain something that is very very small
(invisible to the human eye)

5. Atomic Theory

6. Atomic Theory
The Atomic Theory is the idea of what atoms look like and how they behave.

7. Democritus
Said an object could be cut in half again & again until it became too small that it could no longer be divided.
Called this indivisible particle the “ATOM”
Atoms could not be divided!

8. John Dalton 1803 published Atomic Theory
All matter is made of invisible particles called ATOMS.
Atoms are invisible, indivisible, and in constant motion.
Atoms of the same kind of matter are identical.
2 or more Atoms joined together make up a Molecule.
Compounds consisted of 2 or more different kinds of atoms combined together.

9. J.J. Thomson 1897 Discovered negative charged electron
Plum pudding model
Atom made of a positively charged material with the negatively charged electrons scattered through it.

10. Ernest Rutherford Discovered the Atom is mostly empty space
Small nucleus that contained positively charged protons
Negative electrons scattered around the outside

11. Niels Bohr Solar System Model ~ 1913
Said that electrons orbit the nucleus along certain paths called energy levels or orbitals.
Chemical properties are determined by the electrons in the outermost orbit.

12. Werner Heisenberg 1926
Stated that the exact position of an electron can never be precisely known.
Spherical CLOUD of varying density
The Electron Cloud Model

13. James Chadwick 1932 Discovered a particle without a charge.
The Neutron located in the Nucleus with the Proton

14. ATOMIC MODEL
Each Scientists studied the work of previous scientists, researched,& made new discoveries building upon each others work.
This has led to the current model of the Atom.
Will it change again??? HOW & WHY?