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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
Atomic
Most Number
of the atom’s mass.
neutral atom
equals the # of...
QUARKS
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Mass Number
• mass # = protons + neutrons
• always a whole number
Neutron
+
• NOT on the
Periodic Table!
Electrons
Nucleus
+
+
+
+
+
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
Proton
Nuclide Symbols
Contain the symbol of the element, the mass
number and the atomic number
# protons
+ # neutrons
mass number
# protons
Mass
number
Atomic
number
X
Nuclide Symbols
• Find the
– number of protons = 9 +
– number of neutrons = 10
– number of electrons = 9
– Atomic number = 9
– Mass number = 19
19
9
F
Nuclide Symbols
Find the
– number of protons = 11
– number of neutrons = 12
– number of electrons = 10
– Atomic number = 11
– Mass number = 23
23
11
1+
Na
Sodium ion
Isotopes
Dalton was wrong.
Atoms of the same element can have different
numbers of neutrons
Have different mass numbers
Called isotopes
C-12
California WEB
vs.
C-14
Isotopes
• Atoms of the same element with different
mass numbers.
• Nuclear symbol:
Mass #
12
Atomic #
6
• Hyphen notation: carbon-12
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
C
Isotopes
Neutron
+
Electrons
Nucleus
+
+
+
+
+
Nucleus
Proton
Proton
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
+
+
+
+
Neutron
Electrons
+
+
Carbon-14
Neutrons 8
Protons
6
Electrons 6
Nucleus
27
Co
58.9332
Co-60
ISOTOPES
Co-59
a) element symbol
b) mass of isotope
59
2+
Co
27
p+ =
27
n0 =
33
e- =
27
p+ =
27
n0 =
32
e- =
27
p+ =
27
n0 =
32
e- =
25
Isotopes have different number of...
neutrons
Ions have different number of...
electrons
1
Nonmetals
2
3
M
M
N + 3e-
e-
M+
+
2e- + M2+
N3-
4
Metals form CATIONS
5
Metals
6
Nonmetals form ANIONS
7
Metalloids
Isotopes
• Chlorine-37
– atomic #:
17
– mass #:
37
– # of protons:
17
– # of electrons:
17
– # of neutrons:
20
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
37
17
Cl
Relative Atomic Mass
•
12C
atom = 1.992 × 10-23 g
• atomic mass unit (amu)
• 1 amu = 1/12 the mass of a 12C atom
• 1 p+ = 1.007276 amu
1 n0 = 1.008665 amu
1 e- = 0.0005486 amu
+
Electrons
Nucleus
+
Neutron
+
+
+
+
Nucleus
Carbon-12
Neutrons 6
Protons
6
Electrons 6
Proton
Average Atomic Mass
•
•
•
•
•
How heavy is an atom of oxygen?
There are different kinds of oxygen atoms.
More concerned with average atomic mass.
Based on abundance of each element in nature.
Units are AMUs
Mass spectrums reflect the abundance of
naturally occurring isotopes.
Natural Abundance of Common Elements
Hydrogen
1H
= 99.985%
2H
= 0.015%
Carbon
12C
= 98.90%
13C
= 1.10%
Nitrogen
14N
= 99.63%
15N
= 0.37%
Oxygen
16O
= 99.762%
17O
= 0.038%
Sulfur
32S
= 95.02%
33S
= 0.75%
34S
= 4.21%
36S
= 0.02%
Chlorine
35Cl
= 75.77%
37Cl
= 24.23%
Bromine
79Br
= 50.69%
81Br
= 49.31%
18O
= 0.200%
Average Atomic Mass
• weighted average of all isotopes
• on the Periodic Table
• round to 2 decimal places
Avg.
(mass)(%) + (mass)(%)
Atomic =
100
Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem
Average Atomic Mass
• EX: Calculate the avg. atomic mass of oxygen if its
abundance in nature is 99.76% 16O, 0.04% 17O, and 0.20%
18O.
Avg.
(16)(99.76) + (17)(0.04) + (18)(0.20)
16.00
Atomic =
=
amu
100
Mass
Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem