Download Day 05- Atomic Changes and Std Atomic Notation

Agenda
1) Group Activity: Sig Figs, Accuracy and Precision
GOAL
Use significant digits correctly in calculations
Explain the difference between accuracy and precision.
2) Note + WS: The Atom
GOAL
• describe particles of the atom (p,n,e)
• use standard atomic notation to show mass number and atomic number of an element
• describe what happens to a neutral atom when you change the number of protons, neutrons or electrons
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The Atom
As new discoveries are made our model of the atom has changed. • An atom is the smallest particle of any element that still retains the identity and properties of that element.
• Atoms are made up of even smaller subatomic particles called protons, neutrons, and electrons.
Element Builder Gizmo
http://www.explorelearning.com/index.cfm?
method=cResource.dspDetail&ResourceID=424
Size of the Atom
The average size of the atom is 10­10 m in diameter. Subatomic particles are even smaller than that! Secret Worlds: The Universe Within http://micro.magnet.fsu.edu/primer/java/
scienceopticsu/powersof10/
Subatomic Particles
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Changing the Number of Protons
The number of protons defines the element. If you change the number of protons, you change the element.
Every atom of helium contains 2 protons.
Every atom of sulfur contains 16 protons.
Chemists use the term ATOMIC NUMBER to refer to the
number of protons in the nucleus.
Where in the classroom How many protons can you find the atomic does each atom of number for Aluminum? Aluminum have?
If you could take a proton out of the Al nucleus what would you have?
Changing the Number of Electrons
Neutral atoms do not have a + or ­ charge. # of electrons = # of protons
Ions are atoms with a + or ­ charge. There are 2 types of ions:
1) Cations are atoms that have a + charge because they are missing one or more electrons. ex.
2) Anions are atoms that have a ­ charge because they have extra electrons. ex
For a neutral atom, how would you find the number of e ?
What is the difference between an atom and an ion?
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Changing the Number of Neutrons
Isotopes are atoms of an element that have the same number of protons, but different numbers of neutrons. ­12
The decimal number you see on your periodic table is a weighted average (average atomic mass) of the masses of the isotopes found in nature for that particular element. 4
sulfur­32
16
16
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Standard Atomic Notation (Chemical Notation)
Mass Number = protons + neutrons + Electrons are so tiny that their mass is almost 0 so they are not included.
Atomic Number = protons
How can you find neutrons if you know the atomic number and the mass number?
For Carbon­12
Mass number = 12 = # neutrons + # protons
Atomic number = 6 = # protons
You can find # neutrons if you know the mass # and atomic #
Mass number = n + p
12 = n + 6
n = 6
For Carbon­16
Mass number = 16 = # neutrons + # protons
Atomic number = 6 = # protons
Mass number = n + p
16 = n + 6
n = 10
The Nucleus: Crash Course Chemistry #1 (10 min) Awesome video!!
http://www.youtube.com/watch?v=FSyAehMdpyI
Complete Subatomic Particles Worksheet
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