1. The Atom

2. The beginning of the Atomic Theory
Before the 19th century
People thought an atom was a solid ball
Eugene Goldstein’s 1886 discovery that atoms had positive charges

3. 1897
J.J. Thomas discovered the electron which change the theory drastically
His experiment was based on explaining the reason for a glowing material that was emitted from electric current passing a vacuum tube
He believed there were small parts of the atom getting ripped off
He was later proven right

4. 1911 Ernest Rutherford He played with radioactive alpha particles
fired the particles at gold foil.
He found that while most of the particles passed right through the gold foil, a small number of particles passed through at an angle and some bounced straight back
He believed there were small particles in the middle of the atom that possessed positive charges which were surrounded by electrons

5. The gold foil experiment

6. 1932, James Chadwick
He discovered the third particle called the neutron
He theorized that something had to be in the nucleus to neutralize the charges of the electrons and protons

7. Niels Bohr
This theory established the first description of the behavior of electrons on atoms.
Bohr’s theories led us to the modern structure of an atom that we use today

8. All matter is made up of atoms
There are three parts of an atom
Proton
Neutron
Electron

9. An atom

10. Nucleus
Most dense part of the atom
Center most part of the atom

11. Inside the nucleus

12. Protons They have a positive charge Found inside the nucleus
Makes the difference between elements

13. Neutrons They have a neutral charge or no charge
Found inside the nucleus

14. Electrons They have a negative charge and is the smallest part
Found in the electron cloud
This is outside the nucleus
Electrons move fast around the nucleus and the position of an electron is hard to pin down
The path of the electron is called an orbit

15. One atom is called an element
Lets look at water (H2O)
Water has 2 hydrogens and one oxygen
We have two elements that we are dealing with
Hydrogen = 2 atoms of hydrogen
Oxygen = 1 atom of oxygen

16. Isotopes
They are atoms that have the right number of protons and electrons but differ in the amount of neutrons

17. Elements are arranged in a table called the periodic table
It provides you information about each element
Information like
Mass
How many protons
Element’s symbols

18. Lets take a look at Carbon
Top number is the atomic number
C is the atomic symbol
Carbon is the element
is the mass 6 C
Carbon
12.011

19. What is what? Atomic number Atomic mass
is the amount of protons
Atomic mass
average weight of all the isotopes of that atom
To find the mass of an element you just add the number of protons and neutrons

20. Periodic alignment

21. Rows or Periods
7 rows
2 of the rows are pulled out to make the table easier to read
Properties gradually changes as you move across each row
Become less reactive

22. Columns or Families 18 groups
Properties in groups are similar but not identical
Some groups have special names
A1 alkali metals
A2 alkaline earth metals
A3 – A 12 Transition metals
A 17 Halogens “salt forming”
A 18 Noble gases

23. Properties of Metals have 1-3 electrons in their outer shell.
Solid at room temperature
have 1-3 electrons in their outer shell.
Lose their valence electrons easily
Good electrical conductors and heat conductors
Malleable
can be beaten into thin sheets.
Ductile
can be stretched into wire.
Possess metallic luster

24. Nonmetals Usually have 4-8 electrons in their outer shell
Gain or share valence electrons easily.
Poor conductors of heat and electricity.
Brittle - if a solid
Nonductile.
Do not possess metallic luster
Solids, liquids or gases at room temperature

25. Where are they found