Topics
• Subatomic Particles, their Mass & Electric Charge
• Protons
• Neutrons
• Electrons
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•
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•
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Atomic Number
Isotopes
Atomic Mass
Molar Mass
Average Atomic Mass
• Calculating Average Atomic Mass
What are the Pieces of an Atom?
• Protons
• Neutrons
• Electrons
How do they compare? (Mass)
• Proton Mass = 1.7 x 10-27 kg
• Neutrons Mass = 1.7 x 10-27 kg
• Electrons Mass = 9.1 x 10-31 kg
How do they compare? (Mass)
• Proton Mass = 1.7 x 10-27 kg
• Neutrons Mass = 1.7 x 10-27 kg
• Electrons Mass = 9.1 x 10-31 kg
•
Look at how these number compare
How do they compare? (Mass)
• Proton Mass = 1.7 x 10-27 kg
• Neutrons Mass = 1.7 x 10-27 kg
• Electrons Mass = 9.1 x 10-31 kg
Look at how these number compare
Mass of Subatomic Particles
1.80E-27
Mass in kilograms
•
1.60E-27
1.40E-27
1.20E-27
1.00E-27
8.00E-28
6.00E-28
4.00E-28
2.00E-28
0.00E+00
Proton
Neutron
Electron
How do they compare? (Mass)
Proton
Neutron
Electron
Grape
If an electron is like a grape, which fruit can represent a proton/neutron?
How do they compare? (Mass)
Proton
Neutron
Electron
Grape
If an electron is like a grape,
which fruit can represent a proton/neutron?
How do they compare? (Mass)
Proton
Neutron
Electron
Watermelon
Watermelon
Grape
How do they compare? (Mass)
Proton
Neutron
Electron
1.7 x 10-27 kg
1.7 x 10-27 kg
9.1 x 10-31 kg
Watermelon
Watermelon
Grape
How do they compare? (Electric Charge)
• Neutrons Charge = ?
• Proton Charge = ?
• Electrons Charge = ?
How do they compare? (Electric Charge)
• Neutrons Charge = 0 (Neutral)
• Proton Charge = +1
• Electrons Charge = -1
•
Protons & Electrons have opposite charge
How do they compare?
Proton
Neutron
Electron
1.7 x 10-27 kg
1.7 x 10-27 kg
9.1 x 10-31 kg
Watermelon
Watermelon
Grape
+ 1 = Positive
0 = Neutral
-1 = Negative
How do they compare? (Location)
• Neutrons are
• Protons are
• Electrons are
How do they compare? (Location)
• Neutrons are in the Nucleus
• Protons are in the Nucleus
• Electrons are outside the Nucleus
How do they compare? (Location)
• Neutrons are in the Nucleus
• Protons are in the Nucleus
• Electrons are outside the Nucleus
How do they compare?
Proton
Neutron
Electron
1.7 x 10-27 kg
1.7 x 10-27 kg
9.1 x 10-31 kg
Watermelon
Watermelon
Grape
+ 1 = Positive
0 = Neutral
-1 = Negative
In Nucleus
In Nucleus
Outside Nucleus
What determines the identity (element)
for an atom?
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# or protons
What is the number of protons called?
The Atomic Number
The Atomic Number is listed on the Periodic
Table
What determines the identity (element)
for an atom?
• # or protons
• What is the number of protons called?
• The Atomic Number
• The Atomic Number is listed on the Periodic
Table
What is an Isotope?
• Atoms of the same Element
• With differing numbers of Neutrons
What is an Isotope?
• Atoms of the same Element
• With differing numbers of Neutrons
What is different about the two Helium
Isotopes?
What is the same for the two Helium
Isotopes?
What is an Isotope?
• Atoms of the same Element
• With differing numbers of Neutrons
What is different about the two Helium
Isotopes?
The number of Neutrons (shown in Yellow)
What is the same for the two Helium
Isotopes?
The number of electrons and the number
of protons.
What is an Isotope?
• What are the symbols for this Isotopes?
Use the Symbol for the Element:
He
Add a subscript in front which is the Atomic
Number:
2He
Add the MASS NUMBER as a superscript in front.
Mass Number = (# or P) + ( # or N)
Here Mass Number = (2) +(2)
𝟒
𝟐𝐇𝐞
𝟒
𝟐𝐇𝐞
can also be written a He-4 or Helium-4
Notice that if you subtract the bottom # from
the top number you get the number of
Neutrons.
Try this one:
Try this one:
What makes an Isotope Stable.
For the answer to this visit the https://phet.colorado.edu/en/simulation/build-an-atom
Or to a Search for: phet Build and Atom
Nature does not make all Isotopes in equal amounts. Below are
examples of the Isotopes of Boron, Carbon and Nitrogen and the
Mass Numbers with their abundance illustrated in the graph.
Which Isotope of Carbon is most Abundant?
About what percentage of Carbon atoms are C-13?
If not all Atoms of an Element are the same Mass,
what mass should be assigned to that element?
If not all people have the same height, what
height should be assigned to represent all people?
A weighted Average is used:
A weighted Average gives more influence to the more abundant Isotopes
A weighted Average gives less influence to less abundant Isotopes.
The Average Atomic Mass is given on the Periodic Table
for each element. This number represents several things:
Average Atomic Mass – mass of a single atom
Molar Mass – mass of 6.02 x 1023 atoms
Relative Mass – Mass compared with a Hydrogen Atom