Name
CHAPTER 12
Class
Date
The Periodic Table
SECTION
1 Arranging the Elements
National Science
Education Standards
BEFORE YOU READ
After you read this section, you should be able to answer
these questions:
PS 1b
• How are elements arranged on the periodic table?
• What are metals, nonmetals, and metalloids?
• What patterns are shown by the periodic table?
What Are Patterns of Elements?
By the 1860s, scientists had discovered more than 60
different elements. As they studied these elements, the
scientists saw that some elements had properties that
were very similar. For example, sodium and potassium
are both metals that can explode if put into water. On the
other hand, gold and silver are stable metals that react
very slowly with water.
To understand the elements, chemists needed a way
to organize what they knew about these elements. If the
properties of elements formed a pattern, it would help
scientists understand how elements interact with
one another. A Russian chemist, Dmitri Mendeleev,
discovered a pattern in 1869.
Mendeleev wrote the names of the elements and their
properties on cards. When he arranged the cards in order
of increasing atomic mass, he found that a pattern developed. He put elements that had similar properties in the
same vertical column. See the table below.
Arranging the Elements in a Table
STUDY TIP
Clarifying Concepts Take
turns reading this section
out loud with a partner. Stop
to discuss ideas that seem
confusing.
READING CHECK
1. Describe What discovery
allowed Mendeleev to make
his periodic table?
TAKE A LOOK
Hydrogen
1
Lithium
7
Beryllium
9
Boron
11
Carbon
12
Oxygen
16
Fluorine
19
Sodium
23
Magnesium
24
Aluminum
27
Silicon
28
Sulfur
32
Chlorine
35
Potassium
39
Calcium
40
The elements were placed in order by atomic mass. Sodium is similar to lithium
and potassium, so they are in the same column. The same is true for elements in
the other columns.
2. Make a Prediction Look
at the pattern of atomic
masses of the elements.
Predict where element
X (atomic mass 31) and
element Y (atomic mass 14)
should be placed. Write X
or Y in the correct boxes in
the table.
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The Periodic Table
Name
SECTION 1
Class
Date
Arranging the Elements continued
Say It
Discuss Many things occur
in patterns that are periodic.
In groups of three or four,
discuss things in your life or
in the world around you that
occur at regular intervals.
How many different types of
patterns can you think of?
TAKE A LOOK
3. Identify Look at
Mendeleev’s chart. How
many new elements did
he predict that would be
discovered later?
Math Focus
4. Compare Mendeleev
predicted an atomic mass for
the element that was later
discovered and named
germanium. How much does
germanium’s actual atomic
mass differ from his prediction?
How Were The Patterns Used?
Mendeleev found that the pattern repeated several times.
He started a new row with an element whose properties,
such as reactivity, were similar to lithium. Then all the elements in the first column reacted in a similar way. All the
elements in the second row also had similar properties.
The pattern continued across the table, and then was
repeated for elements in the third row, forming a periodic
pattern. Periodic means “happening at regular intervals.”
Mendeleev found that the pattern of elements repeated
after every seven elements. His table became known
as the periodic table of the elements. The figure below
shows part of a chart that Mendeleev made using his periodic table. Notice that there are several question marks
beside atomic masses.
Mendeleev used question marks
to note elements that he thought
would be found later.
When all the known elements were placed on the
chart, there seemed to be gaps in the pattern. Mendeleev
left blanks in his periodic table where these gaps
appeared. He predicted that elements would be discovered that would fill these blanks.
By 1886, the gaps in the table had been filled by newly
discovered elements. These elements had the properties
that Mendeleev had predicted. The table below compares
one of Mendeleev’s predictions with the actual element,
germanium, discovered in 1871.
Properties of Germanium
Atomic mass
Mendeleev’s
predictions (1869)
Actual properties
70 amu
72.6 amu
Density*
5.5 g/cm
Appearance
dark gray metal
gray metal
Melting point*
high
937°C
3
5.3 g/cm3
* at room temperature and pressure
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The Periodic Table
Name
Class
Date
Arranging the Elements continued
SECTION 1
What Does The Modern Periodic Table
Look Like?
The first periodic table included only 63 elements.
Today, scientists know about more than 100 elements,
although some of them are very rare. The modern table
contains information that is similar to Mendeleev’s, but
there are some differences.
Mendeleev’s periodic table showed the elements in
order of atomic mass. A few of the elements did not
appear to fall in the right order. Mendeleev placed them
where he thought they should be based on their properties. He thought that better atomic mass measurements
would correct the problem.
In 1914, scientists began using atomic numbers. An
atomic number is the number of protons in an atom.
The elements were all in the right place when they were
ordered by atomic number instead of atomic mass. The
figure below shows a modern periodic table.
Each row of elements, from left to right, is called a
period. The physical and chemical properties of elements in a period follow the same pattern as those of the
periods above and below. Each column of elements (top
to bottom) is called a group. Elements in a group tend
to have similar chemical and physical properties. Groups
are sometimes called families.
Atoms of elements in Groups 13–18
have 10 fewer valence electrons than
their group number. However, helium
atoms have only 2 valence electrons.
Atoms of elements in Groups
1 and 2 have the same
number of valence electrons
as their group number.
Atoms of elements in Groups 3–12 do
not have a rule relating their valence
electrons to their group number.
H
1
2
Li
Be
18
13 14 15 16 17 He
B
C
N
O
F
Ne
10 11 12 Al
Si
P
S
Na Mg 3
4
5
6
Cl
Ar
Ca Sc
Ti
V
Cr Mn Fe Co Ni Cu Zn Ga Ge As Se Br
Kr
K
Rb Sr
Y
8
9
Zr Nb Mo Tc Ru Rh Pd Ag Cd In Sb Sb Te
Cs Ba La Hf Ta
Fr
7
W Re Os
Ir
Pt Au Hg Tl
I
Xe
Critical Thinking
5. Explain Why is atomic
number a better property for
organizing the elements than
atomic mass?
TAKE A LOOK
6. Describe How many
groups and how many
periods does the modern
periodic table have? Hint:
hydrogen and helium should
be counted as in the first
period.
Pb Bi Po At Rn
Ra Ac Rf Db Sg Bh Hs Mt Ds Uuu Uub Uut Uuq Uup
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The Periodic Table
Name
SECTION 1
Class
Date
Arranging the Elements continued
How Are the Elements on the Table
Classified?
STANDARDS CHECK
PS 1b Substances react
chemically in characteristic ways
with other substances to form
new substances (compounds)
with different characteristics.
In chemical reactions, the total
mass is conserved. Substances
are often placed in categories
or groups if they react in similar
ways; metals is an example of
such a group.
Word Help: chemical
of or having to do with
properties or actions of
substances
Word Help: reaction
a response or change
7. Compare What are four
categories of elements
found on the periodic table?
When you look at the elements on the periodic table,
there are three classes of elements. Usually, the classes
of elements are related to the number of electrons in the
outer energy level, the valence electrons. The number of
valence electrons increases from left to right in a period.
Based on their properties, the elements are classified as:
• metals - the lighter shade to the left and center of the
periodic table
• nonmetals - the darker shade to the right side of the table
• metalloids - the region shown on either side of a zigzag
line between the metals and nonmetals
• inert gases - Group 18 on the periodic table
METALS
When you look at the periodic table, you can see that
most of the elements are metals. Most metal atoms have few
electrons in their outer energy levels. Except for mercury,
which is a liquid, metals are solids at room temperature. The
figure below shows some of the properties of metals.
Properties of Metals
Metals tend to be
shiny, such as the
reflective surface of
this mirror.
TAKE A LOOK
8. Identify What are five
properties of metals?
Most metals are
malleable, which
means they
can be flattened without
shattering,
such as
a piece of
aluminum foil.
Most metals are
ductile, which
means they can
be drawn into
thin wires, such as
these copper wires.
All metals are good
conductors of
electrical current.
Most metals are
good conductors of heat
(thermal
energy),
such as the
iron in this
griddle.
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The Periodic Table
Name
Class
SECTION 1
Date
Arranging the Elements continued
NONMETALS
Nonmetals are found on the right side of the table.
Atoms of most nonmetals have a nearly full outer energy
level. Many of the nonmetal elements are gases at room
temperature. In general, the properties of nonmetals are
the opposite of the properties of metals. Some of the
properties of nonmetals are described in the figure below.
METALLOIDS
Metalloids are the elements found on either side of the
zigzag line between metals and nonmetals. Their outer
energy levels are about half filled. Metalloids have some
properties of metals and some properties of nonmetals,
as described in the figure below.
READING CHECK
9. Compare How are the
outer energy levels of
nonmetals different from the
outer energy levels of metals?
Properties of Nonmetals and Metalloids
Nonmetals are not malleable or
ductile. Solid nonmetals, such as
carbon in the graphite of pencil lead,
are brittle and will break or shatter
when hit with a hammer.
TAKE A LOOK
10. Identify Circle the
word in the figure’s text that
describes how a metalloid
responds to a hammer blow.
Boron, a metalloid, is almost as hard as a
diamond and is also very brittle. At high
temperatures, it is a good conductor of
electric current.
What Information Is on the Periodic Table?
The next page is a more detailed look at parts of the
periodic table. It includes the two groups to the left side
of the table and the six groups to the right. Each element
occupies one block that includes information about that
element. This includes the element’s name, its atomic
number, and its atomic mass.
Each block also shows the chemical symbol of the element. This is a one or two letter abbreviation that represents that element in a chemical formula. These symbols
are used in the chemical formulas for compounds. If you
see an unfamiliar symbol in a formula, you can use the
periodic table to identify the element.
READING CHECK
11. Describe What is a
chemical symbol?
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The Periodic Table
Name
SECTION 1
Class
Date
Arranging the Elements continued
TAKE A LOOK
12. List What are the four
pieces of information about
an element that are shown
on the periodic table?
Atomic number
Chemical symbol
#ARBON
Element name
Atomic mass
Each square on the periodic table of elements includes the
element’s name, chemical symbol, atomic number, and
atomic mass.
Periodic Table of Elements
0ERIOD
'ROUP
'ROUP
0ERIOD
0ERIOD
Critical Thinking
13. Analyze Relationships
Scientists can make atoms of
large elements which have
not been previously known.
Identify an element that would
have similar properties to an
atom that has 118 protons.
0ERIOD
'ROUP 'ROUP 'ROUP 'ROUP 'ROUP
i
,ITHIUM
"ERYLLIUM
"ORON
#ARBON
>
3ODIUM
"
.ITROGEN
/XYGEN
&LUORINE
(ELIUM
i
.EON
}

-ˆ
*
-

À
-AGNESIUM
!LUMINUM
3ILICON
0HOSPHORUS
3ULFUR
#HLORINE
!RGON
>
>
i
Ã
-i
À
À
0OTASSIUM
#ALCIUM
'ALLIUM
'ERMANIUM
!RSENIC
3ELENIUM
"ROMINE
+RYPTON
,L
-À
˜
-˜
-L
/i
8i
2UBIDIUM
3TRONTIUM
)NDIUM
4IN
!NTIMONY
4ELLURIUM
)ODINE
8ENON
>
/
*L
ˆ
*œ
Ì
,˜
4HALLIUM
,EAD
"ISMUTH
0OLONIUM
!STATINE
2ADON
,>
1ÕÌ
2ADIUM
5NUNTRIUM
A row of
elements is
called a period.
1Õµ
1Õ«
"ARIUM
À
Ã
&RANCIUM
#ESIUM
0ERIOD
'ROUP
0ERIOD
i
ˆ
0ERIOD
(YDROGEN
5NUNQUADIUM 5NUNPENTIUM
A column of
elements is called
a group or family.
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The Periodic Table
Name
Class
SECTION 1
Date
Arranging the Elements continued
How Do You Read The Table?
On the previous page, the top figure shows how to
read a square on the periodic table. The symbol for the
element is generally the largest item on a periodic table.
In this table, the atomic number is above the symbol. The
name of the element and the atomic mass are below it.
Notice that for elements with one-letter symbols, the
symbol is always capitalized. For elements with twoletter symbols, the first letter is capitalized and the
second letter is lower case. Three-letter symbols
represent elements with temporary names.
The bottom figure shows part of the periodic table. In
order to fit onto the page, it only shows eight groups of
elements. All of the elements follow the periodic law.
The periodic law states that the repeating chemical and
physical properties change periodically with the elements’ atomic numbers. An atomic number is the number
of protons in an atom of the element.
Although the atomic number increases from left to
right in every period, the atomic mass does not necessarily do so. There are several places where the atomic mass
of an element is greater than that of the element to its
right. An example is tellurium and iodine in Period 5.
Most tellurium atoms have at least two more neutrons
than iodine atoms have. That is why the atomic mass of
tellurium is higher than the atomic mass of iodine, even
though iodine has one more proton.
READING CHECK
14. Identify What does a
three-letter chemical symbol
show?
Finding the Atomic Number
14
92
-ˆ
1
Silicon
28.1
Atomic Number:
Number of protons:
Uranium
238.0
86
,˜
Radon
(222)
Atomic Number:
Number of protons:
Atomic Number:
Number of protons:
TAKE A LOOK
15. Identify Use the
information from the
periodic table boxes to write
the atomic number and
number of protons for each
element. Fill in the blanks in
the figure to the left.
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The Periodic Table
Name
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Date
Section 1 Review
NSES
PS 1b
SECTION VOCABULARY
group a vertical column of elements in the
periodic table; elements in a group share
chemical properties
period in chemistry, a horizontal row of
elements in the periodic table
periodic describes something that occurs or
repeats at regular intervals
periodic law the law that states that the
repeating chemical and physical properties of
elements change periodically with the atomic
numbers of the elements
1. Compare Which elements would likely have similar properties: two elements in
the same group, or two elements in the same period?
2. Organize Fill in the table below with the correct classification of element.
Location
Classification
Left side and center of periodic table
Right side of periodic table
Zigzag line toward right side of
periodic table
3. Identify Relationships Use the periodic table to answer this question: Are the
properties of rubidium (Rb) more similar to those of cesium (Cs) or those of
strontium (Sr)? Explain your answer.
4. Apply Concepts Use the periodic table on page 218 to identify the elements in the
following compounds: PbS, KBr, RaO
5. Apply Concepts Use the periodic table to determine whether each element is a
metal or a nonmetal: sodium (Na), krypton (Kr), phosphorus (P)
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The Periodic Table
Physical Science Answer Key continued
5.
6.
7.
8.
9.
10.
Particle
Charge
Mass (amu)
Proton
1
1
Neutron
0
1
Electron
1
1/1,840
Review
1. All atoms of an element have the same
They have different numbers of protons.
to keep the protons from moving apart
because protons alone repel each other
the number of protons in the nucleus of an
atom
Element
Hydrogen
Helium
Number of
protons
1
2
Number of
neutrons
0
2
Number of
electrons
1
2
Atomic number
1
2
2.
3.
4.
5.
11. atoms that have the same number of protons
Chapter 12 The Periodic
Table
but a different number of neutrons
12. The number of neutrons does not affect the
chemical properties of oxygen.
13. 5 neutrons in boron-10 and 6 neutrons in
boron-11
14. Isotope
Mass number
Atomic number
Hydrogen-2
2
SECTION 1 ARRANGING THE ELEMENTS
1. He found a pattern in the properties of
2.
1
Helium-4
4
2
Carbon-13
13
6
Oxygen-16
16
8
3.
4.
5.
15. No, the mass number is the atomic number
plus the number of neutrons, so it can never
be smaller than the atomic number.
16. (10 0.20 2.0) (11× 0.80 8.8)
10.8 amu
17. The atom changes into an atom of a
different element because there is one more
proton in the nucleus.
18. Forces in the Atom
Description
Force
Force that affects changes
of particles in the nucleus
weak force
Attractive interaction
between objects with mass
gravitational force
Attractive force between
particles in the nucleus
strong force
Attractive or repulsive
force between objects
with opposite charges
electromagnetic force
number of protons, so they have the same
atomic number. Isotopes have different
numbers of neutrons, so they have different
mass numbers.
neutron, charge is 0, proton, charge is
1, electron, charge is 1
Without neutrons, the repulsion of the protons would cause the nucleus to break apart.
Each atom of carbon has 6 protons in its
nucleus, and each atom of nitrogen has
7 protons. So, the number of neutrons in
carbon-14 is 14 6 8 neutrons. The
number of neutrons in nitrogen-14 is
14 7 7 neutrons.
(69 0.6) (71 0.4) 41.4 28.4 69.8 amu
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
elements.
Top box: Y
Bottom box: X
3
2.6 amu higher than predicted
Every atom of a particular element has
the same atomic number, but atomic mass
depends on the number of neutrons.
7 periods, 18 groups
metals, nonmetals, metalloids, inert gases
Metals are shiny, malleable, ductile, and
good electric current and heat conductors.
Nonmetals have nearly full outer energy levels, but metals have only one or two
electrons in their outer energy level.
There should be a circle around “brittle” or
“very brittle.”
a one or two letter abbreviation that identifies an element
Name, symbol, atomic number, atomic mass
Rn, Xe, Kr, Ar, Ne, or He
an element with a temporary name and
symbol
14, 14, 86, 86, 92, 92
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Physical Science
Physical Science Answer Key continued
Review
1. two elements in the same group
2. Location
Classification
Left side and center of
periodic table
metal
Right side of periodic
table
nonmetal
Zig-zag line toward right
side of periodic table
metalloid
2. Top blank box: elements
Middle blank box: groups
Bottom blank boxes, from left to right: alkali
metals, halogens, noble gases, metals, metalloids, nonmetals
3. Because they are so unreactive, there was
no way to detect the noble gases chemically.
4. All of the nonmetals have outer energy levels that are at least half filled, so they don’t
tend to lose electrons easily.
3. The properties of rubidium are more like
those of cesium because they are both in
Group 1, but strontium is in Group 2.
4. PbS—lead and sulfur, KBr—potassium and
bromine, RaO—radium and oxygen
5. sodium—metal, krypton—nonmetal, phosphorus—nonmetal
Chapter 13 Chemical
Bonding
SECTION 1 ELECTRONS AND CHEMICAL
BONDING
1.
2.
3.
4.
5.
6.
7.
8.
SECTION 2 GROUPING THE ELEMENTS
1. They have the same number of electrons in
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
the outer energy level, so they react in similar ways.
lithium, 3, sodium, 11, potassium, 19, rubidium, 17, cesium, 55, francium, 87
They need to lose two electrons instead of
the one electron that alkali metals lose.
112
mercury
5, 13, 31, 49, 81, 113
It is a lightweight, strong metal.
carbon
N and P
Sulfur is a brittle, yellow solid.
fluorine, 9, chlorine, 17, bromine, 35, iodine,
53, astatine, 65
the noble gases
In the current model, noble gases have a
filled outer energy level, so the theory predicts they would not be reactive. This agrees
with observations.
Although, like the alkali metals, it loses one
electron, it has properties more like those of
the nonmetals.
Atoms gain, lose, or share electrons.
in energy levels outside the nucleus
in the outermost energy level
six protons, six electrons
two
six
to get a full outermost energy level
lose
Review
1. Atoms bond by losing electrons to other
2.
3.
4.
5.
atoms, gaining electrons from other atoms,
or sharing electrons with other atoms.
two dots on inner circle, seven red dots on
outer circle
The easiest way for an atom with seven
valence electrons to complete its outermost
level is to gain one electron from another
atom (but it may share electrons).
The Mg atom can give its two valence electrons to the O atom.
16, 16
SECTION 2 IONIC BONDS
1. when valence electrons are transferred from
2.
Review
1. Both groups are one electron away from
3.
4.
having a stable, full outer electron energy
level. Alkali metals need to lose one electron; halogens need to gain one electron.
5.
6.
one atom to another
Ions are atoms that have gained or lost electrons. Atoms are neutral; ions have a charge.
2+
The attraction between the electron and the
protons has to be broken.
from forming negative ions
nonmetals
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Physical Science