Thompson experimented with ELECTRONS.

8e-
8e-
2e-
Nucleus

Increase in voltage = increase in energy

High voltage power source
1. Hydrogen – spectrum lines are very simple
2. Different elements on periodic table have different colors
3. Colors help determine what elements are in a star for example

Emission Spectra

• Each element gives off a specific colour of light
• These are known as emission spectra
-unique to each element
• If electrons absorb energy they can be bumped to a higher level
• When they fall to a lower level they release energy as light
• Each element has its OWN combination of colours

Atomic Structure

• Atoms are made up of parts called SUBATOMIC particles
• Protons (positive)
• Neutrons (neutral)
• Electrons (negative)
• Electrons have to exist in energy levels

PARTICLE MASS
(multiples of proton) CHARGE
(elementary charges) LOCATION
PROTON 1 +1 Nucleus
NEUTRON 1 0 Nucleus
ELECTRON 1/1837 -1 Outside




Atomic Number

• Atomic Number: number of protons
• Diagram of the element Titanium (Labels: atomic number, symbol, atomic mass, and ion charges)

Isotopes

• The number of protons determine the type of element
• Changing the number of neutrons changes the ISOTOPE of the element
• All isotopes have the same chemical properties
• The nuclei of the three isotopes of hydrogen
Protium Deuterium Tritium
*1 proton *1 proton *1 proton
*1 neutron *2 neutrons

Mass Number

• Mass number is total of protons and neutrons
• Symbol give is A
• Different isotopes have different masses (ex. Helium)
• Mass Number = Atomic Number + Number of Neutrons
A = Z+N
• Examples:
How many protons and neutrons are in each of the elements?
Lithium Titanium Silver
Protons = 3 Protons = 22 Protons = 47
Neutrons = 4 Neutrons = 26 Neutrons = 61

Complete the table
ISOTOPE MASS # ATOMIC # # OF PROTONS # OF NEUTRONS
OS
Osmium 190 76 76 115
Zn
Zinc 65 30 30 35
C
Carbon 14 6 6 8
H
Hydrogen 2 1 1 1

HOMEWORK: 1Periodic Table Assignment & 2Atomic Theory: Isotopes (in the booklet)