1. Atoms and Molecules

2. Atom The smallest particle of an element Examples: Hydrogen Carbon
Chlorine
Titanium

3. The Atomic Model Democritus (450 B.C.) John Dalton (1800)
If you kept cutting a substance in half forever, eventually you would end up with an “uncuttable” particle.
John Dalton (1800)
All substances are made of atoms
Atoms of the same element are exactly alike, and atoms of different elements are different.
JJ Thompson (1897)
Discovered electrons
Developed “plum pudding” model

4. The Atomic Model Ernest Rutherford (1911) Neils Bohr (1913)
Most of the atom’s mass is found in a region in the center called the nucleus
Neils Bohr (1913)
Electrons travel around the nucleus in definite paths.
Erwin Schrodinger
There are regions inside the atom
where electrons are likely found

5. Nucleus
The central core of an atom, contains protons and usually neutrons

6. Proton
Small positively charged particles found in the nucleus of an atom

7. Neutron
Small uncharged particles found in the nucleus of an atom

8. Nuclear Energy Fission Fusion
The potential energy stored in the nucleus of an atom
Fusion
Fission

9. Electron
Tiny, negatively-charged, high-energy particles that move around the outside of the nucleus

10. Electrical Energy The energy of moving electrical charges Charge-
A definite amount of electricity, positive or negative

11. Element
A substance that cannot be broken down into any other substances

13. Atoms continued Atomic Number= number of protons
Atomic Mass= number of protons + neutrons
# Electrons = # Protons

14. Calculations Magnesium Oxygen 12 protons 12 electrons
12 neutrons (24-12=12)
Oxygen
8 protons
8 electrons
8 neutrons (16-8=8)

15. Molecule
A particle made of two or more atoms bonded together

16. Chemical Bond
The force that holds the atoms together

17. Chemical energy
The potential energy stored in chemical bonds