YAY NOTES 
 Helpful hint
Anything in pink italics are hints.
If writing dude is not present on the page then you are welcome
to write the information but they are not required notes
You only need to leave space if the notes specifically tell you!
OBJ 2.5: Determine the number of protons, neutrons and
electrons in a neutral atom using the periodic table
Definitions
 NEUTRAL: having no charge
 NEUTRAL ATOM: an atom having no charge
 Number of protons = number of electrons
 Neutron: A neutral subatomic particle that holds the atom
together
 Mass Number
M=P+N
Element
Atomic
number
P=e
Mass number Protons
(M)
(P)
Be
8
12
Ne
Fe
11
S
Neutrons
(N)
5
9
12
11
30
20
12
10
15
Electrons
(e)
19
9
How do all of these particles stay in
place?
 Both attraction and repulsion occurs between subatomic
particles
 These forces have an important impact on the structure
of the atom
Definitions
 Law of attraction: opposite charges attract; like charges
repel.
 Proton (+) & Proton (+):
 Proton (+) & Electron (-):
 Electron (-) & Electron (-):
Repel
Attract
Repel
 Strong Nuclear Force:The force that occurs between protons
and neutrons.
 137 times stronger then the attraction between protons and
electrons
 This is why protons in the nucleus do not repel.
GIST the following statement in 12
words or less.
 Shielding is an effect in which the outer electrons in atom are
“shielded” from the nucleus. In other words, outer electrons
do not feel the attraction of the nucleus as strongly as inner
electrons.
 Don’t copy this whole statement.Write a 12 word GIST
(summary) of the information given
OBJ 2.6: Draw a diagram of a specific atom showing the
correct location of subatomic particles
Remember
 The nucleus is in the center of the atom and contains protons
and neutrons
 The electrons are located in the orbitals (shells) outside of
the nucleus
Model of Helium – Draw!
Nucleus
Leave 1/3 of a page for two more
drawings
YAY!
 Your take home notes for this section are done!