Unit b matter and chemical change notes(timeline)

Unit b matter and chemical change notes(timeline)

1. Timeline

2. 8000 BC Used stones & bone for tools Started to control Fire (cooking, baking)

3. 6000-1000 BC Found metals Gold became very valuable Chemists were only interested in materials of value

4. 4500 BC Copper was discovered and led to bronze Humans could now make hard strong tools (swords, ​ spears & other tools)

5. 1200 BC Hittites discovered how to extract iron from rocks This started the iron age (iron + copper = steel ) Started to extract oils & juices from plants

6. 400 BC Greek philosopher (Democritus) used the word ​ atomos to describe the smallest particles that could ​ not be broken down any further

7. 350 BC Aristotle another more popular geek philosopher had ​ the idea that all matter came from Earth, Water, Fire ​ and Air. Because Aristotle was more respected people accepted ​ his theory over Democritus' idea.

8. The Next 2000 Years Most work with matter was done by Alchemists, ​ people who were part chemist and part magician. Most of their job was working for the King to turn ​ metals into gold.

9. Late 1500 People really started to investigate the ​ world around them Started to form the scientific method.

10. 1660 Robert Boyle experimented with ​ the behaviors of gases. He believed everything was made ​ of tiny particles of different size ​ and shape . Boyle thought the purpose of ​ chemistry was to determine the ​ types of particles in each ​ substance.

11. 1780 Antoine Laurent Lavoisier "the father of modern ​ chemistry " Studied chemical interactions and developed a system of naming them. (everyone could use the same names)

12. 1808 John Dalton suggested matter was made of elements . Pure substances contained no other substances (all one ​ type of atom) Developed the billiard ball model (atoms are solid ​ spheres) C Cl H Fe N O Na

13. 1897 J. J. Thomson discovered electrons Developed a raisin bun model of matter . Negative electrons balance out positive sphere so atom ​ has no electrical charge.

14. 1904 Hantaro Nagaoka modeled matter after the solar system Large positive center with negative electrons orbiting ​ around

15. 1908 Ernest Rutherford (working at McGill in Montreal) ​ found evidence of central nucleus. In his experiment he shot positively charge particles ​ through thin foil and found mostly empty space and the ​ nucleus was the core that would stop the particles.

16. 1922 Niels Bohr working with Rutherford found electrons ​ orbit is specific shells (circular orbits ) Electrons jump between shells by gaining or losing ​ energy

17. More 1922 James Chadwick found protons & neutrons (particles ​ with no charge) inside the nucleus of an atom.

18. Today People still use Bohr model of the atom Quantum mechanics found electrons exist in a charged ​ cloud around the nucleus.