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General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
1
Chapter 3 Atoms and Elements
3.1
Elements and Symbols
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
2
Elements are
pure substances that cannot be separated into simpler substances by ordinary laboratory processes
the building blocks of matter
gold carbon aluminum
Elements
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
3
Sources of Some Element Names
Some elements are
named for planets,
mythological figures,
minerals, colors,
scientists, and places.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
4
A symbol
represents the name of an element
consists of 1 or 2 letters
starts with a capital letter
Examples:
1-Letter Symbols 2-Letter Symbols
C carbon Co cobalt
N nitrogen Ca calcium
F fluorine Al aluminum
O oxygen Mg magnesium
Symbols of Elements
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
5
Some symbols are derived from Latin names, as shown
below.
Cu, copper (cuprum) Au, gold (aurum)
Fe, iron (ferrum) Ag, silver (argentum)
Symbols from Latin Names
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
6
Physical Properties of Elements
The physical properties of an element
are observed or measured without changing its
identity
include the following:
shape
color
odor
taste
density
melting point
boiling point
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
7
Physical Properties of Elements
Some physical properties of
copper are:
Color Red-orange
Luster Very shiny
Melting point 1083 °C
Boiling point 2567 °C
Conduction
of electricity Excellent
Conduction
of heat Excellent
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
8
Select the correct symbol for each of the following:
A. Calcium
1) C 2) Ca 3) CA
B. Sulfur
1) S 2) Sl 3) Su
C. Iron
1) Ir 2) FE 3) Fe
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
9
Select the correct symbol for each of the following:
A. Calcium
2) Ca
B. Sulfur
1) S
C. Iron
3) Fe
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
10
Select the correct name for each symbol.
A. N
1) neon 2) nitrogen 3) nickel
B. P
1) potassium 2) phlogiston 3) phosphorus
C. Ag
1) silver 2) agean 3) gold
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
11
Select the correct name for each symbol.
A. N
2) nitrogen
B. P
3) phosphorus
C. Ag
1) silver
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
12
Chapter 3 Atoms and Elements
3.2
The Periodic Table
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
13
Groups and Periods
On the periodic table
Groups contain elements with similar properties and
are arranged in vertical columns.
Periods are the horizontal rows of elements.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
14
Groups and Periods (continued)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
15
Periodic Table
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
16
Group Numbers
Group Numbers
Use numbers 1–18 to identify the columns from left to
right.
Use the letter A for the representative elements (1A to
8A) and the letter B for the transition elements.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
17
Representative Elements
Several groups of representative elements are
known by common names.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
18
Alkali Metals
Group 1A(1), the alkali metals, includes lithium,
sodium, and potassium.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
19
Halogens
Group 7A(17),
the halogens,
includes
chlorine,
bromine, and
iodine.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
20
Identify the element described by the following:
A. Group 7A(17), Period 4
1) Br 2) Cl 3) Mn
B. Group 2A(2), Period 3
1) beryllium 2) magnesium 3) boron
C. Group 5A(15), Period 2
1) phosphorus 2) arsenic 3) nitrogen
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
21
A. Group 7A (17), Period 4
1) Br
B. Group 2A (2), Period 3
2) magnesium
C. Group 5A(15), Period 2
3) nitrogen
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
22
Metals, Nonmetals, and Metalloids
The heavy zigzag line
separates metals and
nonmetals.
Metals are located to
the left.
Nonmetals are located
to the right.
Metalloids are located
along the heavy zigzag
line between the metals
and nonmetals.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
23
Metals
are shiny and ductile
are good conductors of heat and electricity
Nonmetals
are dull, brittle, and poor conductors of heat and
electricity
are good insulators
Metalloids
are better conductors than nonmetals, but not as
good as metals
are used as semiconductors and insulators
Properties of Metals, Nonmetals,
and Metalloids
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
24
Comparing a Metal, Metalloid,
and Nonmetal
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
25
Identify each of the following elements as 1) metal,
2) nonmetal, or 3) metalloid.
A. sodium ____
B. chlorine ____
C. silicon ____
D. iron ____
E. carbon ____
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
26
Identify each of the following elements as 1) metal, 2)
nonmetal, or 3) metalloid.
A. sodium 1 metal
B. chlorine 2 nonmetal
C. silicon 3 metalloid
D. iron 1 metal
E. carbon 2 nonmetal
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
27
Match the elements to the description.
A. Metals in Group 4A(14)
1) Sn, Pb 2) C, Si 3) C, Si, Ge, Sn
B. Nonmetals in Group 5A(15)
1) As, Sb, Bi 2) N, P 3) N, P, As, Sb
C. Metalloids in Group 4A(14)
1) C, Si, Ge, 2) Si, Ge 3) Si, Ge, Sn, Pb
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
28
Match the elements to the description.
A. Metals in Group 4A (14)
1) Sn, Pb
B. Nonmetals in Group 5A(15)
2) N, P
C. Metalloids in Group 4A(14)
2) Si, Ge
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
29
Chapter 3 Atoms and Elements
3.3
The Atom
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
30
Dalton’s Atomic Theory
Atoms
are tiny particles of matter
of an element are similar to
each other but are different
from atoms of other
elements
of two or more different
elements combine to form
compounds
are rearranged to form new
combinations in a chemical
reaction
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
31
Subatomic Particles
Atoms contain subatomic particles.
Protons have a positive (+) charge.
Electrons have a negative (–) charge.
Like charges repel, and unlike
charges attract.
Neutrons are neutral.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
32
Rutherford’s Gold-Foil Experiment
In Rutherford’s gold-foil experiment, positively
charged particles
were aimed at atoms of gold
mostly went straight through the atoms
were deflected only occasionally
Conclusion:
There must be a small, dense, positively charged
nucleus in the atom that deflects positive particles
that come close.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
33
Rutherford’s Gold-Foil Experiment
(continued)
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
34
Structure of the Atom
An atom consists
of a nucleus that
contains protons
and neutrons
of electrons in a
large, empty
space around the
nucleus
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
35
Atomic Mass Scale
On the atomic mass scale for subatomic particles:
1 atomic mass unit (amu) is defined as 1/12 of the
mass of the carbon-12 atom.
A proton has a mass of about 1 (1.007) amu.
A neutron has a mass of about 1 (1.008) amu.
An electron has a very small mass, 0.000549 amu.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
36
Particles in the Atom
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
37
Learning Check
Identify each statement as describing a(n) 1) proton,
2) neutron, or 3) electron.
A. __ found outside the nucleus
B. __ has a positive charge
C. __ is neutral
D. __ found in the nucleus
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
38
Solution
Identify each statement as describing a(n) 1) proton,
2) neutron, or 3) electron.
A. 3 found outside the nucleus
B. 1 has a positive charge
C. 2 is neutral
D. 1, 2 found in the nucleus
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
39
Chapter 3 Atoms and Elements
3.4
Atomic Number and Mass Number
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
40
The atomic number
is specific for each element
is the same for all atoms of an element
is equal to the number of protons in an atom
appears above the symbol of an element
Atomic Number
11
Na
Atomic Number
Symbol
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
41
Examples of atomic number and number of protons:
Hydrogen has atomic number 1; every H atom has
one proton.
Carbon has atomic number 6; every C atom has six
protons.
Copper has atomic number 29; every Cu atom has
29 protons.
Gold has atomic number 79; every Au atom has 79
protons.
Atomic Number and Protons
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
42
State the number of protons in each.
A. A nitrogen atom
1) 5 protons 2) 7 protons 3) 14 protons
B. A sulfur atom
1) 32 protons 2) 16 protons 3) 6 protons
C. A barium atom
1) 137 protons 2) 81 protons 3) 56 protons
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
43
State the number of protons in each.
A. A nitrogen atom
2) atomic number 7; 7 protons
B. A sulfur atom
2) atomic number 16; 16 protons
C. A barium atom,
3) atomic number 56; 56 protons
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
44
An atom
of an element is electrically neutral; the net charge
of an atom is zero
has an equal number of protons and electrons.
number of protons = number of electrons
of aluminum has 13 protons and 13 electrons; the
net charge is zero
13 protons (13+) + 13 electrons (13–) = 0
Number of Electrons in an Atom
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
45
Mass Number
The mass number
represents the number of particles in the nucleus.
is equal to the
number of protons + number of neutrons
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
46
Atomic Models
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
47
An atom of zinc has a mass number of 65.
A. How many protons are in this zinc atom?
1) 30 2) 35 3) 65
B. How many neutrons are in the zinc atom?
1) 30 2) 35 3) 65
C. What is the mass number of a zinc atom that has
37 neutrons?
1) 37 2) 65 3) 67
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
48
An atom of zinc has a mass number of 65.
A. How many protons are in this zinc atom?
1) 30 (atomic number 30)
B. How many neutrons are in the zinc atom?
2) 35 (65 – 30 = 35)
C. What is the mass number of a zinc atom that has 37 neutrons?
3) 67 (30 + 37 = 67)
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
49
An atom has 14 protons and 20 neutrons.
A. Its atomic number is
1) 14 2) 20 3) 34
B. Its atomic number is
1) 14 2) 20 3) 34
C. The element is
1) Si 2) Ca 3) Se
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
50
Chapter 3 Atoms and Elements
3.5 Isotopes and Atomic Mass
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
51
Isotopes
are atoms of the same element that have different
mass numbers
have the same number of protons but different
numbers of neutrons
Isotopes
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52
A nuclear symbol
represents a particular atom of an element
gives the mass number in the upper left corner and
the atomic number in the lower left corner
Example: An atom of sodium with atomic number
11 and a mass number 23 has the following atomic
symbol:
mass number
atomic number
Nuclear Symbol
23 11 Na
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
53
For an atom, the nuclear symbol gives the number of
protons (p+)
neutrons (n)
electrons (e–)
8 p+ 15 p+ 30 p+
8 n 16 n 35 n
8 e– 15 e– 30 e–
Nuclear Symbols
16 8 O 31
15 P 65 30
Zn
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
54
Naturally occurring carbon consists of three isotopes,
C-12, C-13, and C-14. State the number of protons,
neutrons, and electrons in each of the following.
protons ______ ______ ______
neutrons ______ ______ ______
electrons ______ ______ ______
Learning Check
12 6 C
13 6 C
14 6 C
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55
protons 6 p+ 6 p+ 6 p+
neutrons 6 n 7 n 8 n
electrons 6 e– 6 e– 6 e–
Solution
12 6 C
13 6 C
14 6 C
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
56
Write the nuclear symbols for atoms with the
following subatomic particles:
A. 8p+, 8n, 8e– ___________
B. 17p+, 20n, 17e– ___________
C. 47p+, 60n, 47e– ___________
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
57
A. 8p+, 8n, 8e–
B. 17p+, 20n, 17e–
C. 47p+, 60n, 47e–
Solution
16 8 O
37
17 Cl
107
47 Ag
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
58
Learning Check
1. Which of the following pairs are isotopes of the
same element?
2. In which of the following pairs do both atoms have
8 neutrons?
A.
B.
C.
12 6 X 15
7 X
12 6 Z 14
6 Z
15 7 Z 16
8 Z
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
59
Solution
1. B
Both nuclear symbols represent isotopes of carbon
with six protons each, but one has 6 neutrons and
the other has 8.
2. C
An atom of nitrogen (atomic number 7) and an atom
of oxygen (atomic number 8) each have 8 neutrons.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
60
Isotopes of Magnesium
In naturally occurring magnesium, there are 3 isotopes.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
61
Isotopes of Sulfur
A sample of naturally
occurring sulfur contains
several isotopes with the
following abundances:
Isotope % Abundance
95.02
0.75
4.21
0.02
32
16 S
33
16 S
34 16 S 36 16 S
32 33 34 36
16 16 16 16 S S S S
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
62
Atomic Mass
The atomic mass of an element
is listed below the symbol of each
element on the periodic table
gives the mass of an “average” atom of
each element compared to C-12
is not the same as the mass number
Na
22.99
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
63
Some Elements and Their Atomic
Mass
Most elements have two or more isotopes that
contribute to the atomic mass of that element.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
64
Atomic Mass for Cl
The atomic mass of chlorine is
based on all naturally
occurring Cl isotopes
not a whole number
the weighted average
of the Cl-35 and Cl-37
isotopes
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
65
Atomic Mass for Mg
The atomic mass of Mg is
based on all naturally
occurring Mg isotopes
not a whole number
the weighted average
of the Mg-24, Mg-25, and
Mg-26 isotopes
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
66
Using the periodic table, give the atomic mass of
each element.
A. calcium __________
B. aluminum __________
C. lead __________
D. barium __________
E. iron __________
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
67
Using the periodic table, give the atomic mass of
each element.
A. calcium 40.08 amu
B. aluminum 26.98 amu
C. lead 207.2 amu
D. barium 137.3 amu
E. iron 55.85 amu
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
68
An atom has 14 protons and 20 neutrons.
A. Its atomic number is
1) 14
B. Its atomic number is
3) 34 (14 + 20 = 34)
C. The element is
1) Si (atomic number 14)
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
69
Chapter 3 Atoms and Elements
3.6
Electron Energy Levels
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
70
Electromagnetic Radiation
Electromagnetic radiation
is energy that travels as waves through space
is described in terms of wavelength and
frequency
moves at the speed of light in a vacuum
speed of light = 3.0 x 108 m/s
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71
Electromagnetic Spectrum
The electromagnetic spectrum
arranges forms of energy from lowest to highest
arranges energy from longest to shortest wavelengths
shows visible light with wavelengths from 700–400 nm
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
72
Learning Check
1. Which of the following has the shortest wavelength?
A. microwaves B. blue light C. UV light
2. Which of the following has the lowest energy?
A. red light B. blue light C. green light
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
73
Solution
1. Which of the following has the shortest wavelength?
C. UV light
2. Which of the following has the lowest energy?
A. red light
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
74
Spectra
White light that passes
through a prism
is separated into all
colors that together are
called a continuous
spectrum
gives the colors of a
rainbow
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75
Atomic Spectrum
An atomic spectrum consists of
lines of different colors formed when light from a
heated element passes through a prism
photons emitted when electrons drop to lower
energy levels
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76
Example of Atomic Spectra
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
77
Electron Energy Levels
Electrons are arranged in
specific energy levels that
are labeled n = 1, n = 2,
n = 3, and so on
increase in energy as n
increases
have the electrons with the
lowest energy in the first
energy level (n = 1) closest
to the nucleus
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78
Energy Level Changes
An electron absorbs
energy to “jump” to a
higher energy level.
When an electron falls to
a lower energy level,
energy is emitted.
In the visible range, the
emitted energy appears
as a color.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
79
In each of the following energy level changes, indicate
if energy is 1) absorbed, 2) emitted, or 3) not changed.
A. An electron moves from the first energy level (n = 1)
to the third energy level (n = 3).
B. An electron falls from the third energy level to the
second energy level.
C. An electron moves within the third energy level.
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
80
In each of the following energy level changes, indicate
if energy is 1) absorbed, 2) emitted, or 3) not changed.
A. An electron in an atom moves from the first energy
level (n = 1) to the third energy level (n = 3).
1) absorbed
B. An electron falls from the third energy level to the
second energy level.
2) emitted
C. An electron moves within the third energy level.
3) not changed
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
81
Sublevels
Sublevels
contain electrons with the same energy
are found within each energy level.
are designated by the letters s, p, d, and f
The number of sublevels is equal to the value of the
principal quantum number (n).
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82
Number of Sublevels
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83
Energy of Sublevels
In any energy level
the s sublevel has the lowest energy
the s sublevel is followed by the p, d, and f sublevels
(in order of increasing energy)
higher sublevels are possible, but only s, p, d, and f
sublevels are needed to hold the electrons in the
atoms known today
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84
Orbitals
An orbital
is a three-dimensional space
around a nucleus where an
electron is most likely to be found
has a shape that represents
electron density (not a path the
electron follows)
can hold up to 2 electrons
contains two electrons that must
spin in opposite
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85
s Orbitals
An s orbital
has a spherical shape
around the nucleus
increases in size around the
nucleus as the energy level
n value increases
is a single orbital found in
each s sublevel
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86
p Orbitals
A p orbital
has a two-lobed shape
is one of three p orbitals that make up each p
sublevel
increases in size as the value of n increases
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87
Sublevels and Orbitals
Each sublevel consists of a specific number of
orbitals.
An s sublevel contains one s orbital.
A p sublevel contains three p orbitals.
A d sublevel contains five d orbitals.
An f sublevel contains seven f orbitals.
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
88
Electrons in Each Sublevel
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
89
Learning Check
Indicate the number and type of orbitals in each of the
following:
A. 4s sublevel
B. 3d sublevel
C. n = 3
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90
Solution
A. 4s sublevel
one 4s orbital
B. 3d sublevel
five 3d orbitals
C. n = 3
one 3s orbital, three 3p orbitals,
and five 3d orbitals
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91
Learning Check
The number of
A. electrons that can occupy a p orbital is
1) 1 2) 2 3) 3
B. p orbitals in the 2p sublevel is
1) 1 2) 2 3) 3
C. d orbitals in the n = 4 energy level is
1) 1 2) 3 3) 5
D. electrons that can occupy the 4f sublevel is
1) 2 2) 6 3) 14
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92
Solution
The number of
A. electrons that can occupy a p orbital is
2) 2
B. p orbitals in the 2p sublevel is
3) 3
C. d orbitals in the n = 4 energy level is
3) 5
D. electrons that can occupy the 4f sublevel is
3) 14
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
93
Chapter 3 Atoms and Elements
3.7
Electron Configurations
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94
Energy levels are filled with electrons
in order of increasing energy
beginning with quantum number n = 1
beginning with s followed by p, d, and f
Order of Filling
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95
Energy Diagram for Sublevels
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96
An orbital diagram shows
orbitals as boxes in each sublevel
electrons in orbitals as vertical arrows
electrons in the same orbital with opposite spins (up
and down vertical arrows)
Example:
Orbital diagram for Li
1s2 2s1 2p
filled half-filled empty
Orbital Diagrams
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
97
Order of Filling
Electrons in an atom
fill orbitals in sublevels of the same type with
one electron each until all sublevels are half full
then pair up in the orbitals using opposite spins
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98
Writing Orbital Diagrams
The orbital diagram
for carbon consists of
two electrons in the 1s
orbital
two electrons in the 2s
orbital
one electron each in
two of the 2p orbitals
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
99
Write the orbital diagrams for
A. nitrogen
B. oxygen
C. magnesium
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
100
Write the orbital diagrams for
A. nitrogen
1s 2s 2p
B. oxygen
1s 2s 2p
C. magnesium
1s 2s 2p 3s
Solution
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
101
An electron configuration
lists the sublevels filling with electrons in order of
increasing energy
uses superscripts to show the number of electrons
in each sublevel
for neon is as follows:
number of electrons
sublevel 1s22s22p6
Electron Configuration
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102
Period 1 Configurations
In Period 1, the first two electrons enter the 1s orbital
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
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Abbreviated Configurations
An abbreviated configuration shows
the symbol of the noble gas in brackets that
represents completed sublevels
the remaining electrons in order of their sublevels
Example: Chlorine has a configuration of
1s22s22p63s23p5
[Ne]
The abbreviated configuration for chlorine is
[Ne]3s23p5
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
104
Period 2 Configurations
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
105
Period 3 Configurations
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
106
A. The correct electron configuration for nitrogen is
1) 1s22p5 2) 1s22s22p6 3) 1s22s22p3
B. The correct electron configuration for oxygen is
1) 1s22p6 2) 1s22s22p4 3) 1s22s22p6
C. The correct electron configuration for calcium is
1) 1s22s22p63s23p63d2
2) 1s22s22p63s23p64s2
3) 1s22s22p63s23p8
Learning Check
General, Organic, and Biological Chemistry Copyright © 2010 Pearson Education, Inc.
107
A. The correct electron configuration for nitrogen is
3) 1s22s22p3
B. The correct electron configuration for oxygen is
2) 1s22s22p4
C. The correct electron configuration for calcium is
2) 1s22s22p63s23p6s2
Solution
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108
Write the electron configuration and abbreviated
configuration for each of the following elements:
A. Cl
B. S
C. K
Learning Check
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A. Cl
1s22s22p63s23p5 [Ne]3s23p5
B. S
1s22s22p63s23p4 [Ne]3s23p4
C. K
1s22s22p63s23p64s1 [Ar]4s1
Solution
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Sublevel Blocks on the
Periodic Table
The periodic table consists of sublevel blocks
arranged in order of increasing energy.
Groups 1A(1) to 2A(2) = s level
Groups 3A(13) to 8A(18) = p level
Groups 3B(3) to 2B(12) = d level
Lanthanides/Actinides = f level
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Sublevel Blocks
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Using Sublevel Blocks
To write a configuration
using sublevel blocks
Locate the element on
the periodic table.
Starting with H in 1s,
write each sublevel
block in order going
left to right across
each period.
Write electrons for
each block.
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113
Using the periodic table, write the electron configuration
for silicon.
Solution:
Period 1 1s block 1s2
Period 2 2s → 2p blocks 2s2 2p6
Period 3 3s → 3p blocks 3s23p2 (at Si)
Writing all the sublevel blocks in order gives:
1s22s22p63s23p2
Writing Electron Configurations
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114
The 4s orbital has a lower energy than the 3d
orbitals.
In potassium (K), the last electron enters the 4s
orbital instead of the 3d (as shown below).
1s 2s 2p 3s 3p 3d 4s
Ar 1s2 2s22p6 3s23p6
K 1s2 2s22p6 3s23p6 4s1
Ca 1s2 2s22p6 3s23p6 4s2
Sc 1s2 2s22p6 3s23p6 3d1 4s2
Ti 1s2 2s22p6 3s23p6 3d2 4s2
Electron Configurations of the d
Level
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115
Using the periodic table, write the electron configuration
for manganese.
Solution:
Period 1 1s block 1s2
Period 2 2s → 2p blocks 2s2 2p6
Period 3 3s → 3p blocks 3s2 3p6
Period 4 4s → 3d blocks 4s2 3d5 (at Mn)
Writing all the sublevel blocks in order gives:
1s22s22p63s23p64s23d5
Writing Electron Configurations
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116
4s Block
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117
3d Block
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4p Block
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119
A. The last two sublevel blocks in the electron
configuration for Co are
1) 3p64s2
2) 4s24d7
3) 4s23d7
B. The last three sublevel blocks in the electron
configuration for Sn are
1) 5s25p24d10
2) 5s24d105p2
3) 5s25d105p2
Learning Check
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120
A. The last two sublevel blocks in the electron
configuration for Co are
3) 4s23d7
B. The last three sublevel blocks in the electron
configuration for Sn are
2) 5s24d105p2
Solution
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121
Using the periodic table, write the electron
configuration and abbreviated configuration for
each of the following elements:
A. Zn
B. Sr
C. I
Learning Check
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122
A. Zn
1s22s22p63s23p64s23d10
[Ar]4s23d10
B. Sr
1s22s22p63s23p64s23d104p65s2
[Kr]5s2
C. I
1s22s22p63s23p64s23d104p65s24d105p5
[Kr]5s24d105p5
Solution
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123
Learning Check
Give the symbol of the element that has
A. the abbreviated configuration [Ar]4s23d6
B. four 3p electrons
C. two electrons in the 4d sublevel
D. the electron configuration
1s22s22p63s23p64s23d2
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Solution
Give the symbol of the element that has
A. the abbreviated configuration [Ar]4s23d6 Fe
B. four 3p electrons S
C. two electrons in the 4d sublevel Zr
D. the electron configuration Ti
1s22s22p63s23p64s23d2
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Chapter 3 Atoms and Elements
3.8
Periodic Trends
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Valence Electrons
The valence electrons
determine the chemical properties of the elements
are the electrons in the outermost, highest energy
level
are related to the Group number of the element
Example: Phosphorus has 5 valence electrons.
5 valence
electrons
P Group 5A(15) 1s22s22p63s23p3
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All the elements in a group have the same number of
valence electrons.
Example: Elements in Group 2A(2) have two (2)
valence electrons.
Be 1s22s2
Mg 1s22s22p63s2
Ca [Ar]4s2
Sr [Kr]5s2
Groups and Valence Electrons
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Periodic Table and
Valence Electrons
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State the number of valence electrons for each.
A. O
1) 4 2) 6 3) 8
B. Al
1) 13 2) 3 3) 1
C. Cl
1) 2 2) 5 3) 7
Learning Check
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130
State the number of valence electrons for each.
A. O
2) 6
B. Al
2) 3
C. Cl
3) 7
Solution
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131
State the number of valence electrons for each.
A. Calcium
1) 1 2) 2 3) 3
B. Group 6A (16)
1) 2 2) 4 3) 6
C. Tin
1) 2 2) 4 3) 14
Learning Check
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132
State the number of valence electrons for each.
A. Calcium
2) 2
B. Group 6A (16)
3) 6
C. Tin
2) 4
Solution
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133
State the number of valence electrons for each.
A. 1s22s22p63s23p1
B. 1s22s22p63s2
C. 1s22s22p5
Learning Check
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134
State the number of valence electrons for each.
A. 1s22s22p63s23p1 3
B. 1s22s22p63s2 2
C. 1s22s22p5 7
Solution
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135
Electron-Dot Symbols
An electron-dot symbol
indicates valence electrons
as dots around the symbol of
the element
of Mg shows two valence
electrons as single dots on the
sides of the symbol Mg
· · · Mg · or Mg · or · Mg or · Mg
·
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Writing Electron-Dot Symbols
The electron-dot symbols for
Groups 1A(1) to 4A(14) use single dots · · Na · · Mg · · Al · · C ·
· Groups 5A(15) to 7A(17) use pairs and single dots. · · · · · P · : O · · ·
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Groups and Electron-Dot Symbols
in a group, all the electron-dot symbols have the
same number of valence electrons (dots).
Example: Atoms of elements in Group 2A(2) each
have 2 valence electrons.
2A(2)
· Be ·
· Mg ·
· Ca ·
· Sr ·
· Ba ·
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138
A. X is the electron-dot symbol for 1) Na 2) K 3) Al
B. X is the electron-dot symbol for
Learning Check
1) B 2) N 3) P
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Solution
A. X is the electron-dot symbol for 1) Na 2) K
B. X is the electron-dot symbol for
2) N 3) P
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140
Atomic Size
Atomic size
is described using the atomic radius
is the distance from the nucleus to the valence
electrons
increases going down a group
decreases going across a period from left to right
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Atomic Size (continued)
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Atomic Radius Within A Group
Atomic radius
increases going
down a group
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Learning Check
Select the element in each pair with the larger atomic
radius.
A. Li or K
B. K or Br
C. P or Cl
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Solution
Select the element in each pair with the larger atomic
radius.
A. K is larger than Li
B. K is larger than Br
C. P is larger than Cl
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145
Ionization Energy
Ionization energy
is the energy it takes to remove a valence electron
from an atom in the gaseous state
Na(g) + Energy (ionization) Na+(g) + e–
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Ionization Energy and Valence
Electrons
Ionization energy
decreases going down
a group as the distance
between the nucleus
and valance electrons
increases
146
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Ionization Energy
The ionization
energies of
metals are
low
nonmetals
are high
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Learning Check
Select the element in each pair with the higher
ionization energy.
A. Li or K
B. K or Br
C. P or Cl
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Solution
Select the element in each pair with the higher
ionization energy.
A. Li is higher than K
B. Br is higher than K
C. Cl is higher than P