Do Now: Pass in homework to be peer
graded and returned
Objective: 4.3 Distinguishing Atoms
Home Work: Pg. 119 # 25 – 29, 32
1.
2.
3.
8.
9.
Indivisible and indestructible
By using experimental methods
Scanning Tunneling Microscope
Protons, Neutrons, and Electrons
A positively charges nucleus surrounded by electrons
which take up most of the volume
10. Proton + 1 , Neutron + 1, Electron – 1/1840
13. So many of the alpha particles went straight through
the gold foil.
14. Rutherford had a positively charged dense nucleus
that was tiny in comparison with the atom as a whole
while Thompson’s “plumpudding” model had
electrons that were stuck in the large positive area.
4.3 Distinguishing Among Atoms
Atomic Number
• Elements are different because they contain
different numbers of protons.
Atomic Number =
Atomic Number
• Elements are different because they contain
different numbers of protons.
Atomic Number = the number of protons in
the nucleus of an atom of a
given element.
Mass Number
• Mass Number = The total number of protons
and neutrons in the nucleus
of an atom
Mass Number
• Mass Number = The total number of protons
and neutrons in the nucleus
of an atom
# of Neutrons = Mass Number - Atomic Number
Isotopes
• Isotopes = Atoms with the same number of
protons but different number of neutrons
Isotopes
• Isotopes = Atoms with the same number of
protons but different number of neutrons
Neon – 20
Neon – 21
Neon – 22
Atomic Mass
• An Atomic Mass Unit (amu)
is defined as 1/12th of the mass
of a Carbon-12 atom
Atomic Mass Numbers on the Periodic Table are
averages of the elements in nature.
The Periodic Table
If there are around 117 elements why do you
think we organize them as in the Periodic Table
and don’t simply list them 1 -117?
The Periodic Table
Periods are the horizontal rows
Groups are the vertical columns
• Do Now – Current Events and Chemistry
• Objective – Chapter 4 Review
5.1 Models of the Atom
• Homework – Start Pg. 132 # 1-6 (Due Tuesday)