2. Matter cannot be created/destroyed, although it may be rearranged.
History of the Atom and Chemical Foundations
Lavoisier
The law of conservation of mass/matter says that the mass of a closed system will remain constant, regardless of the processes acting inside the system.
Matter cannot be created/destroyed, although it may be rearranged.
Any chemical process in a closed system, the mass of the reactants must equal the mass of the products.
Mg into Hcl acid in a sealed container
Married a 14 year old when he was 28!
Beheaded at the age of 50 during the French Revolution

3. Law of Definite Proportions published by Proust in 1799
History of the Atom and Chemical Foundations
Law of Definite Proportions published by Proust in 1799
It was originally argued that compounds could combine in any ratio. There was no fundamental understanding of mixture and chemical compound
Proust-
Used artificial made copper carbonate (CuCO3) and comparing it to naturally found copper carbonate. showed they had the same proportion between the three elements (Cu, C, O)

4. John Dalton History of the Atom and Chemical Foundations
Dalton's Atomic Theory
John Dalton
Elements are made of tiny particles called atoms.
All atoms of a given element are identical.
The atoms of a given element are different from those of any other element; the atoms of different elements can be distinguished from one another by their respective relative weights.
Atoms of one element can combine with atoms of other elements to form chemical compounds; a given compound always has the same relative numbers of types of atoms.
Atoms cannot be created, divided into smaller particles, nor destroyed in the chemical process; a chemical reaction simply changes the way atoms are grouped together.
A lunar crater is named after Dalton! And the Atomic Mass Unit is also known as a Dalton (Da)

5. JJ Thompson
Cathode Ray Tube- helped establish the identity of the electron
Gives off electrons
Vacuum
Magnet - redirected the electrons- nobody knows why the magnetic field bends

6. Original Model of the Atom
Plum Pudding Model
An atom made of thousands of electrons would have a very high, negative electric charge. This was not observed, as atoms are usually uncharged. In 1906 Thomson suggested that atoms contained far fewer electrons, a number roughly equal to the atomic number. This is only one electron in the case of hydrogen, far fewer than the thousands originally suggested.
These electrons must have been balanced by some sort of positive charge. The distribution of charge and mass in the atom was unknown. Thomson proposed a 'plum pudding' model, with positive and negative charge filling a sphere only one ten billionth of a metre across.
This plum pudding model was generally accepted. Even Thomson's student Rutherford, who would later prove the model incorrect, believed in it at the time.
These newly discovered electrons must have been balanced by some sort of positive charge.
Thomson proposed a 'plum pudding' model, with positive and negative charge filling a sphere.
Even Thomson's student Rutherford, who later proved model incorrect, believed it at the time.

7. Rutherford’s Gold Foil Experiment
Expected- particles to go straight
through the plum pudding with its
diffuse positive charge
Actual- some particles bounced back! 1 in 8000,

8. Gold Foil Experiment Modified the Model of the atom Rutherford Model
Often referred as the planetary model-
now also considered incorrect

9. Bohr Model of the Atom
1913-Bohr speculated that electrons orbit around the atomic nucleus. Electron orbits were at a fixed distance from the nucleus and had definite energy. The electron was said to travel in a fixed-energy orbit that was referred to as an energy level.

10. Electromagnetic Spectrum
Visible light spectrum portion of whole spectrum
High energy waves
Low energy waves
When you add energy….
Emission Spectra of Fe (atomic number 26)
Lots of electrons!

11. Emission Spectra Supports the Bohr Model