Chaos. That’s something we are all familiar with.

1. Chaos. That’s something we are all familiar with.

2. There’s even a movie called chaos. Life is full of it and we all try to reduce it. We want to feel organized. Few of us want the world to be chaotic.

3. Chaos goes beyond our lives and our world. This writer addresses chaos throughout the universe and its stunning complexity. Throughout human history, we have tried to make more sense out of the world around us. To reduce the chaos, we tried to perceive a more simpler underlying fabric of the world.

4. Thales (600 B.C.) In 600 B.C. the Greek philosopher Thales proposed that everything in the world was made from water. Water was the only element. All living things consume water and perhaps water is creating all the matter living things are composed of. Water

5. Xenophanes (500 B.C.) Earth Water In 500 B.C. the Greek philosopher Xenophanes felt water couldn’t be the element for everything. It seemed the world was made two elements, earth and water.

6. Empedocles (440 B.C.)Four elements Earth (more commonly called dirt) Water 60 years later Empedocles felt the universe required four elements. Earth, water, fire, and air. Fire Air

7. As leaves change their color, you can see the fire that they contain. Anything that burns will reveal that it is made of the four elements (At this point, I crumpled some paper and lit a match to it.) Notice there is fire in this paper. Also, I feel wind rising from it. As I hold this cold beaker above it, you can see water condensing on it. So the dry paper actually has water in it. Finally as it burns out you see the ashes, which is like dirt or earth.

8. Democritus Athens, Greece 400 B.C. 40 years later, Democritus said, Ok there may be four elements, but I believe these elements are not as they appear.

9. The mountains look solid and the water seems smooth, but that because there’s a limit to our vision.

10. For example, from a distance, we cannot see the individual grains of sand that this beach is made from.

11. However, up close we know there are individual grains.

12. I think elements are like this. They are made of individual particles, that in huge numbers become visible and know to us.

13. The smallest particles of matter are indivisible. Since atomos is the Greek word for “indivisible” I shall call these particles “atoms”. “Atoms” cannot be destroyed, so there is conservation of matter. I also believe that these small particles are indivisible. In other words, there is a limit to how small matter can be broken. Since atomos is the Greek word for indivisible I shall call these particles atoms. Atoms cannot be destroyed, so there is conservation of matter. We may see water evaporate or wood burn, but the matter or atoms are still around.

14. Aristotle Athens, Greece 340 B.C. Aristotle also had opinions on chemistry. However, Aristotle had the most influence on the history of chemistry. About 60 years later, Aristotle also had opinions on chemistry. However, he had the most influence on the history of chemistry. Besides chemistry, he also tackled physics, biology, psychology, and logic.

15. It’s ironic that the theories of Aristotle which were most accepted were also the most incorrect. For example, he proposed and embraced the mystical fifth element. It took chemists 2,000 years to recognize that there was no mystical fifth element.

16. Aristotle disagreed with Democritus • Democritus said atoms cannot be divided. • You cannot place restraints on the gods. Therefore, matter cannot be made up of indivisible particles. Atoms cannot exist.

17. The concept of the atom fell out of favor for 2,000 years until… Democritus’ view of what atoms might look like.

18. John Dalton England 1796 John Dalton began teaching when he was 12. Dalton was a humble man with several apparent handicaps: he was poor; he was not articulate; he was not a skilled experimentalist; and he was color-blind. Dalton is best known for his atomic theory, which revolutionized the science of chemistry and brought back Democritus’ concept of the atom.

19. Elements are composed of minute, indivisible particles called atoms

20. All atoms of that element are alike. Plus those atoms are not like the atoms of any other element. Copper Gold

21. Chemical compounds are formed by the union of two or more atoms of different elements.

22. Atoms combine to form compounds in simple ratios, such as 1:1, 1:2, 2:2, 1:3, and so forth. Law of Definite Proportions

23. Atoms of two elements may combine in different ratios to form more than one compound. We call this:The Law of Multiple Proportions

24. Reactions are just a rearrangement of atoms. Oxygen and hydrogen gas reacting to form water

25. Ba(OH)2.8H2O(s ) + 2 NH4SCN(s ) --> Ba(SCN)2(s ) + 10 H2O(l ) + 2 NH3(g ) Reactions are just a rearrangement of atoms. O Ba O O Ca S O O H H O

26. Arranged from light to heavy by their relative weights Through experiments, Dalton was getting rough estimates on the relative weights of known elements. The second is Azote, “A” for no and “Zote” for life. The gas was nitrogen, and living things die if only breathing nitrogen. Some were not elements. Lime is actually calcium and oxygen combined, but Dalton didn’t know that. Dalton’s Elements

27. This is the Swedish chemist, Johan Berzelius. Like Dalton, he was finding the relative weights of the elements. Berzelius in credited for the naming convention we use for elements. Johan Jacob Berzelius from Sweden

28. Berzelius’ Symbols for Elements • Older elements take the symbol from their Latin name. • Fe comes from ferrum not iron. • Instead of G for gold he wants Au from aurum. • Instead of S for Silver he wants Ag from argentum. • Newer symbols come from English names. • O comes from oxygen. • 2000 experiments over a ten-year period to determine accurate relative atomic weights for all the elements now known.

29. John Newlands England 1867 Researchers had already began to arrange and classify elements: Metals vs. non-metals In tables of increasing atomic weight John Newlands from England had a different way to arrange elements.

30. Certain elements resembled one another in behavior. • Chlorine, bromine & iodine • violently corrosive • form acids • Lithium, sodium, potassium • Unite violently with oxygen or water • Oxides form caustic aqueous solutions Every eighth element have similar characteristics Li Be B C N O F Na Mg Al Si P S Cl K Ca ? ? As Se Br I call this the “Law of Octaves”

31. “Law of Octaves” He presented his theory to the England Chemical Society and was laughed at. They said to arrange it alphabetically.

32. Dmitri Ivanovich Mendeleev Russia 1871 Periodic Law Like Newlands, he used lithium, sodium, and potassium plus the chlorine family as guide posts Here is someone you don’t laugh at.

33. Orginally Mendeleev arranged the elements with common properties in rows instead of columns. But here are the two groups of elements that acted as guide posts.

34. His table helped others find the missing elements. Gallium Germanium

35. As a tribute to Mendeleev, here is his Periodic Table of the Elements carved in stone.

36. In an effort to understand the chaos around us, we found order. The complexity of the universe is tamed by this table. It represents a comforting reminder that chaos is not in control.

37. Periodic Table of the Elements Elements are listed by increasing mass. But grouped by reoccuring (periodic) properties

38. Learning Check Name an element that has similar properties to chlorine (Cl). Name an element that has similar properties to sodium (Na). Name an element that has similar properties to copper (Cu).

39. Under the symbol of each element is that element's relative mass For example Helium shows the atomic mass of 4.00 and Oxygen is 16.00. That means that one atom of oxygen is 4 times heavier than helium. Oxygen has 4 times more protons and 4 times more neutrons (not shown in table) that account for this.

40. Learning Check How many times heavier is a calcium atom compared to a neon atom? How many times heavier is a calcium atom compared to a helium atom? How many times heavier is oxygen compared to carbon?

41. Periodic Table of the Elements To understand it further we need to look closer at the makeup of the atom.

42. CHEMISTRY It’s all aboutbuilding blocks

43. Electrons (-) Neutrons Protons (+) Evolution of the atom 300 BC. 1912 Now

44. How do electrons “think”? + + +

45. Electrons “dislike” other electrons

46. Electrons “love” protons • Electrons are strongly attracted to protons. The more protons present the stronger the attraction. +

47. + + Likes RepelOpposites Attract

48. What do electrons do when both protons and electrons are present? They get as close to the protons as possible while maintaining as much distance as possible from other electrons. + + ` + + +

49. + What would the right electron do?

50. - - + + What would electrons in two hydrogen atoms do? - - + + BOND Remember this is a simplistic version of the electron.