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.