1. The Atom

2. Atom
The smallest unit of matter

3. Democritus 5th Century B.C.E. Keep breaking material farther down
Eventually you would have an ‘atom’- unable to be cut

4. Dalton 1803 Billiard Ball Model An atom is a solid sphere
All elements are made up of the same atom

5. Thomson 1897 Plumb Pudding Model
The sphere of the ‘billiard ball’ is positive with negative charges spread throughout

6. Rutherford 1908 The ‘billiard ball’ is positive in the middle
There are negative spheres surrounding the positive middle

7. Neils Bohr 1915 Electrons travel in orbits around the positive middle
Orbits are a specific shape

8. Nucleus
Consists of Protons and Neutrons
Protons- positive charge
Neutrons- neutral/no charge
Electrons
Negative charge
2 electrons in 1st ring
8 electrons in 2nd ring
Valence electrons: electrons in outer ring

9. Neutral Atom
Same number of electrons as there are protons

10. How to Draw an Atomic Diagram of an Element
Determine number of protons & electrons in element
Look at atomic #
Draw nucleus as a circle- write # of protons in the circle
Add 1st electron orbital with appropriate # of electrons stop at 2 e-
Add 2nd orbital with appropriate # of electrons stop at 8 e-
Completed when all electrons add up to atomic #
Electron Orbital
Maximum # electrons
1st 2
2nd 8
3rd 18
4th 32

11. Draw the atomic diagram for Phosphorus

12. Ion Atom with a positive or negative charge Negative- extra e-
Positive- missing e-

13. Aston Discovered the Isotope Isotope
Same number of protons and electrons
Different number of neutrons
Changes the overall weight of the atom

14. Elements Element: Consists entirely of ONE type of atom
Roughly 100 elements
Metals
Non-metals
Gases
Shiny
Little to no shine
High Boiling Temperature
Varies
Solid at room temperature (except mercury)
Solid (brittle) or liquid at room temperature
Gas at room temperature
Good conductors of heat and electricity
Poor conductors of heat and electricity
Left side/middle of the periodic table
Upper right side of periodic table
Right-most column on periodic table

15. Name of Element Symbol Carbon Oxygen Hydrogen Nitrogen Chlorine
Phosphorus
Silicon
Fluorine
Magnesium
Sodium

16. Periodic Table Rows: 1. Not alike in properties
First element a solid, last element is a gas
Atomic mass increases from left to right
Columns:
Alike in properties
Same number of valence electrons