Index
Atoms and Elements
Chemistry Unit 02
Based on the PowerPoints by Kevin Boudreux.
Honors Unit 02 Module 03: The Structure of Atoms
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Index
Honors Unit 02 Module 03
THE STRUCTURE OF ATOMS
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Index
The Atom and the Subatomic Particles
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The Atom and the Subatomic Particles
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Atomic Number, Mass Number, and Isotopes
• What makes elements different from one another is the
number of protons in their atoms, called the atomic
number (Z). All atoms of the same element contain
the same number of protons.
• The mass number (A) is the sum of the number of
protons (Z) and neutrons (N) in the nucleus of an atom:
A=Z+N
• Isotopes of an element have the same atomic number,
but different #’s of neutrons. Isotopes of an element
have nearly identical chemical behavior.
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Atomic Number (z) Summarized
• Symbol = z
• Number of protons (+).
• On periodic table.
• # of protons determines the
element
•
(Add a proton to oxygen it becomes fluorine –
nuclear reactions only)
6
C
Carbon
12.011
• For a neutral atom,
# electrons = # protons
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Mass Number (A) Abridged Version
• Total number of protons and neutrons.
• Not on the periodic table.
• Determines the isotope.
6
C
• A = #neutrons + #protons
• #neutrons = A - #protons
•
bigger number
Carbon
12.011
• Close to the mass of the isotope.
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Index
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Atomic Symbols
• The atomic symbol specifies information
about the nuclear mass (i.e. the mass number),
atomic number, and the charge on a particular
element. Every element has a one- or twoletter symbol based on its English or Latin
name.
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Index
Sometimes referred to as nuclear notation or isotopic notation.
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Ions
• Neutral atoms have the same numbers of electrons as
protons. In many chemical reactions, atoms gain or lose
electrons to form charged particles called ions.
• For example, sodium loses one electron, resulting in a
particle with 11 protons and 10 electrons, having a +1
charge:
+
-
Na ® Na + e
• Positively charged ions are called cations.
• Fluorine gains one electron, resulting in a particle with 9
protons and 10 electrons, having a -1 charge:
-
F +e ® F
-
• Negatively charged ions are called anions.
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Index
Hyphen notation of isotopes
“isotope” hyphen “mass number”
Isotope-A
Carbon-12
Oxygen-18
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Nuclear or Isotopic Notation of
Isotopes
A
Z
Carbon-14
A= mass #
X
Z=atomic #
X=element
14
6
C
Big number on
top.
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Index
1.
2.
3.
4.
5.
Important Facts about
Subatomic Particles
# of electrons determines the charge of the atom
• #e- = #p+ Charge is zero (neutral)
• #e- > #p+ (greater than) Charge is negative.
• #e- < #p+ (less than) Charge is positive.
# of protons determines what element it is.
# of protons and neutrons determines the mass
of the atom. (Since electron’s mass ~0)
An electron and proton can combine to form a
neutron and vice versa. (nuclear reactions only)
A neutron has the most mass.
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How to Determine the Number of e-, p+ & n
#p+ = atomic #
If charge = 0, then #p+ = #e#e- = #p+ - charge
#e- - reason it out – Who’s wining? By how
much?
5. charge = #p+ - #e6. #n = A – Z (mass # - atomic #)
1.
2.
3.
4.
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Example
How many protons? Electrons?
Ca
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Example
How many protons? electrons?
Mg2+
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Examples
How many electrons?
F-
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Example
How many protons? electrons?
P3-
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Your Turn
How many protons? Electrons?
Mg
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Your Turn
How many protons? Electrons?
Li
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Your Turn
How many protons? Electrons?
Cu
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Your Turn
How many protons? electrons?
K+
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Your Turn
How many protons? electrons?
S2-
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Example
How many protons, electrons, and neutrons
does carbon-14 have? (A=14)
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#Neutrons
How many protons, electrons, and neutrons
does neon-22 have? (A=22)
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Your turn
How many neutrons does oxygen-18 have?
(A=18)
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Your turn
How many protons, electrons, and neutrons
does Silicon-30 have? (A=30)
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Your turn
Determine the number of protons, electrons, and
neutrons of Boron-12.
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Index
Hyphen notation examples
Put in hyphen notation
A nuclide of fluorine has 9 protons and 10
neutrons.
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Index
Hyphen notation of isotopes
“isotope” hyphen “mass number”
Isotope-A
Carbon-12
Oxygen-18
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Hyphen notation examples
Put in hyphen notation
A nuclide of calcium has a mass number of 44
and an atomic number of 20.
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Hyphen notation examples
Put in hyphen notation
A nuclide of nickel has a 28 protons and 32
neutrons.
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Your turn
Put in hyphen notation
A nuclide of arsenic has an atomic number of 33
and a mass number of 75
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Your turn
Put in hyphen notation
An unknown nuclide has a 30 protons and 34
neutrons.
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Your turn
Put in hyphen notation
A nuclide has a 37 protons and 48 neutrons.
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Index
Nuclear or Isotopic Notation of
Isotopes
A
Z
Carbon-14
A= mass #
X
Z=atomic #
X=element
14
6
C
Big number on
top.
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Nuclear notation Examples
Put in nuclear notation.
A nuclide has 8 protons and 8 neutrons.
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Nuclear notation Examples
Put in nuclear notation.
A nuclide has a mass number of 130 and an
atomic number of 56.
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Nuclear notation Examples
Determine the number of electrons, neutrons,
and protons of:
U
239
92
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Your turn
Determine the number of electrons, neutrons,
and protons of:
124
54
Xe
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Your turn
Determine the number of electrons, neutrons,
and protons of:
124
53
I
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Your turn
Put in nuclear notation. Tin-113
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Your turn
Put in nuclear notation. A nuclide has 27
protons, 30 neutrons, and 24 electrons.
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Tutorials EPN
• Tutorials on how to find the number of electrons,
protons, and neutrons
– http://www.youtube.com/watch?v=Z4v1_Qj60a8&feature=youtu.be
– http://www.youtube.com/watch?v=n4WZ0-fItt8
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Tutorials - Isotopes
• Tutorials for writing the isotopes in hyphen
notation or nuclear (isotopic) notation
– http://www.youtube.com/watch?v=BYiu0kIWd30
– http://www.youtube.com/watch?v=8oBedASNVxg
&feature=c4overview&list=UUVdtS_cnwkNuP6fGs4efTEw
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