1. ATOMIC
STRUCTURE

2. Dalton’s Theory All matter is made up of tiny particles called atoms
Atoms of the same element are identical in size, mass, properties
Atoms cannot be subdivided, created or destroyed
Atoms of different elements combine to form chemical compounds

3. How much of this is true?
Some of Dalton’s Theory about the atom has been altered based on new information
This gives us the …..

4. Modern Atomic Theory All matter is made up of atoms.
Atoms of the same element are chemically similar
Atoms of an element may not have the same mass (Isotopes)
Atoms are not subdivided, created or destroyed in chemical reactions.

5. Isotopes Ions Atoms of the same element with different masses
Protons are the same
Neutrons differ
Looks like: uranium-235 Or
Have an unequal number of protons and electrons
Have an overall positive or negative charge
Ions

6. Atomic Number Mass Number It represents the # of protons
It can also represent the # of electrons if the atom is neutral
Mass Number
Represents the # of protons + # of neutrons
# of Neutrons = Mass Number – Atomic Number

7. Subatomic Particles
Particle Location Charge Mass

8. Periodic Table 13 Al

9. Periodic Table 19 K

10. Nuclear Symbols Fe Al 27 13 57 26

11. Nuclear Symbols Cl Al 3+ 1- 27 13 35 17

12. Elements, Isotopes and Ions
127I 127I- 129I

13. Describing the Atom
J.J. THOMPSON - Showed that atoms are made of particles
CATHODE
RAY
TUBE \

14. Describing the Atom MILLIKAN
Calculated the charge on a single electron

15. Rutherford Showed that atom had both + and -
charges : Radiation and Magnets (p106)

16. Rutherford See p 95 GOLD FOIL EXPERIMENT
Showed atom mostly empty space & its
mass is contained in a very small area
GOLD FOIL
EXPERIMENT
See p 95
C:\Documents and Settings\Teacher\Desktop\1Rutherford_Expt.avi

17. Gold Foil Experiment

18. Flame Test
*Electrons exist in energy levels (or ‘shells’).
*When exposed to an energy source, electrons may become ‘excited’ and jump to a higher energy level.
*When the electron returns to its ‘ground state’ a photon of light is released.
*The photon of light is always the same wavelength (and the same color) for each element.