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Slide 1
Particles in the Atom
Slide 2
Particles in the
Atom
Electrons
(-) charge
no mass
located outside the nucleus
1 amu
located inside the nucleus
1 amu
located inside the nucleus
Protons
(+) charge
Neutron
no charge
Slide 3
Subatomic Particles
Name
Symbol
Relative
Charge mass
Actual
mass (g)
Electron
e-
-1
1/1840
9.11 x 10-28
Proton
p+
+1
1
1.67 x 10-24
Neutron
no
0
1
1.67 x 10-24
Slide 4
Structure of the Atom
– There are two regions
• The nucleus
– With protons and neutrons
• Positive charge
• Almost all the mass
–
Electron cloud
• Most of the volume of an atom
• The region where the electron can be found
Slide 5
Subatomic Particles
ATOM
ATOM
NUCLEUS
NUCLEUS
ELECTRONS
ELECTRONS
PROTONS
PROTONS
NEUTRONS
NEUTRONS
POSITIVE
Positive
CHARGE
Charge
NEUTRAL
Neutral
CHARGE
Charge
NEGATIVE
CHARGE
Negative Charge
equal in a
MostNumber
of the atom’s mass.
Atomic
neutral atom
equals the # of...
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Slide 6
Size of an atom
•Atoms are incredibly tiny.
•Measured in picometers (10-12 meters)
–Hydrogen atom, 32 pm radius
•Nucleus tiny compared to atom
–Radius of the nucleus near 10-15 m.
–Density near 1014 g/cm
•IF the atom was the size of a stadium, the
nucleus would be the size of a marble.
Slide 7
Counting the Pieces
Atomic Number = number of protons
# of protons determines kind of atom
Atomic Number = number of electrons in a
neutral atom
Mass Number = the number of protons + neutron
Slide 8
Symbols
Contain the symbol of the element, the
mass number and the atomic number
# protons
+ # neutrons
mass number
# protons
Mass
number
Atomic
number
X
Slide 9
Symbols
•Find the
–number of protons 9
–number of neutrons 10
–number of electrons 9
–Atomic number 9
–Mass number 19
19
9
F
Slide 10
Symbols
•Find the
–number of protons 35
–number of neutrons 45
–number of electrons 35
–Atomic number 35
–Mass number 80
80
35
Br
Slide 11
Symbols
•Find the
–number of protons 11
–number of neutrons 12
–number of electrons 11
–Atomic number 11
–Mass number 23
23
11
Na
Slide 12
Symbols
•Find the
–number of protons 23
–number of neutrons 28
–number of electrons 23
–Atomic number 23
–Mass number 51
51
23
V
Slide 13
Symbols
If an element has 60 protons and
144 neutrons what is the
–Atomic number 60
–Mass number 204
–Number of electrons 60
–Complete symbol
60
204
Nd