1. H ISTORY OF T HE S TUDY OF M ATTER September 2 nd, 2014

2. W HAT IS M ATTER ? Anything that has a mass and occupies volume For chemists matter is atoms composed of protons, neutrons and electrons.

3. 450BC –D EMOCRITUS AND A TOMISM Atomism – the world consists of atoms (stuff) and void (empty space / void) There are infinite shapes and sizes of atoms Things formed by combining atoms in clusters The word atom ( atomus) literally means uncuttable It was believed that atoms could not be destroyed

4. A RISTOTLE AND THE NATURE OF MATTER (350BC) Applied the four elements Earth, fire, water, air Matter to Aristotle is what explains change A horse eats grass Once eaten it is no longer grass, it becomes part of the horse Eventually that matter becomes both the horse and poop! So matter is not a substance it is a ‘principle’ To be something it must have ‘form’

5. A NTOINE L AVOISIER – I N 1777 defined the term element for the first time. any basic substance that could not be broken down into other substances by the methods of chemistry. Any substance that could be broken down was a compound

6. J OHN D ALTON – EARLY 1800’ S Believed all matter (atoms) were in direct contact with one another His theory stated that: Everything is made from atoms Nothing can be simpler than an atom Atoms can not be made or destroyed Chemical reactions are made when atoms are moved around, put with other atoms or taken away from a group of other atoms Atoms of the same element are the same, because they have the same mass Atoms can only be joined in special ratios

7. D MITRI M ENDELEEV IN 1869 published the first version of the periodic table It groups atoms by their atomic number ( how many protons they have ) Elements in the same column, or period, usually have similar properties.

8. J. J. T HOMSON (1897) was the first man to discover electrons He realized they had a negative charge unlike protons (positive) and neutrons (no charge). Thomson created the plum pudding which stated that an atom was like plum pudding: the dried fruit (electrons) were stuck in a mass of pudding (protons).

9. A LBERT E INSTEIN IN 1905 Used mathematics to prove that the seemingly random movements were due to the reactions of atoms by doing so he conclusively proved the existence of the atom with mathematics!!!

10. E RNEST R UTHERFORD (1909) proved that electrons are very small compared to protons and neutrons. proved that atoms are mostly empty space. Electrons are so small they make up only 1% of an atoms mass

11. N IELS B OHR (1913) introduced the Bohr Model. This model showed that electrons orbit the nucleus in fixed circular orbits. Improvements to the Bohr model have been made since it was first introduced.

12. WERNER HEISENBERG (1901 – 1976) Introduced the uncertainty principle 1925 If you know determine exactly where an electron is at a certain point in time you can’t predict its momentum. AND VICE VERSA You can either know a electrons momentum or position but not both.

13. E RWIN S CHRÖDINGER (1935) The most accurate model so far comes from the Schrödinger equation realized that the electrons exist in a cloud around the nucleus, called the electron cloud The Schrödinger equation is used to find out where an electron is likely to be found in its orbital.

14. THE ELECTRON CLOUD

15. M ORE SUBATOMIC PARTICLES Leptons Mesons Bosons Quarks Gluons Baryons WE ARE NOT IN KANSAS ANYMORE!!!