PERIODIC TABLE
Chapter Fifteen: Elements and
the Periodic Table
15.1 The Periodic Table of the
Elements
15.2 Properties of the Elements
Chapter 15.1 Learning Goals
Differentiate physical and chemical
properties of elements.
Explain how the periodic table is
organized.
Identify metals, semimetals, and
nonmetals on the periodic table.
Investigation 15A
The Periodic Table
Key Question:
How is the periodic table organized?
15.1 Physical properties
Characteristics that you can see through
direct observation are called physical
properties.
Physical properties include color, texture,
density, brittleness, and state (solid,
liquid, or gas).
Melting point, boiling point, and specific
heat are also physical properties.
15.1 Physical properties
 A physical change does not result in
a new substance being formed.
15.1 Chemical properties
Properties that can only be observed
when one substance changes into a
different substance are called chemical
properties.
Any change that transforms one
substance into a different substance is
called a chemical change.
15.1 The Periodic Table
The periodic table organizes the elements
according to how they combine with other
elements (chemical properties).
The periodic table is organized in order of
increasing atomic number.
15.1 The Periodic Table
The periodic table is
further divided into
periods and groups.
Each horizontal row
is called a period.
Each vertical column
is called a group.
15.1 The Periodic Table
All the elements in
Group 1 of the periodic
table form similar
compounds.
The metals lithium,
sodium, and potassium
all form compounds
with a ratio of 2 atoms
of the metal to 1 atom
of oxygen.
15.1 Atomic Mass
The mass of individual atoms is so
small that the numbers are difficult to
work with.
To make calculations easier, scientists
use the atomic mass unit (amu).
The atomic mass of any element is the
average mass (in amu) of an atom of
each element.
15.1 Atomic Mass
Atomic masses
differ from mass
numbers because
most elements in
nature contain more
than one isotope.
15.1 Atomic Number
 Remember, the atomic number is the
number of protons all atoms of that element
have in their nuclei.
If the atom is neutral, it will have the same
number of electrons as protons.
15.1 Groups of the periodic table
The first group is known as the
alkali metals.
The alkali metals are soft and silvery
in their pure form and are highly
reactive.
This group includes the elements
lithium (Li), sodium (Na), and
potassium (K).
15.1 Groups of the periodic table
The group two metals include
beryllium (Be), magnesium (Mg), and
calcium (Ca).
They also bond easily with oxygen.
15.1 Halogens
The halogens tend to be toxic
gases or liquids in their pure form.
Fluorine (F), chlorine (Cl), and
bromine (Br) form salts when the
bond with alkali metals.
15.1 Noble Gases
The noble gases, including
the elements helium (He),
neon (Ne), and argon (Ar).
These elements do not
naturally form chemical
bonds with other atoms
and are almost always
found in their pure state.
Chapter Fifteen: Elements and
the Periodic Table
15.1 The Periodic Table of the
Elements
15.2 Properties of the Elements
Chapter 15.2 Learning Goals
Differentiate the electrical and thermal
conductivity of metals and nonmetals.
Define periodicity and discuss
examples.
Predict properties of an element based
on its position on the periodic table.
Investigation 15B
Atomic Challenge
Key Question:
What information can you get from the
periodic table?
15.2 Properties of the elements
Most of the pure elements are solid
at room temperature.
Only 11 naturally occurring elements
are a gas.
Only 2 elements (Br and Hg) are
liquid at room temperature.
15.2 Periodic properties of elements
Periodicity means properties repeat
each period (row) of the periodic
table.
This pattern is an example of periodicity.
15.2 Thermal and electrical
conductivity
Electricity is the movement
of electric charge, usually
electrons.
Some materials allow
electrons to flow easily
through them.
We call these materials
electrical conductors.
15.2 Thermal and electrical
conductivity
Like copper, most
metals are good
thermal conductors.
That is one reason pots
and pans are made of
metal.
15.2 Thermal and electrical
conductivity
Elements on the far right
of the table are called nonmetals.
Nonmetals make good
insulators.
An insulator is a material
which slows down or
stops the flow of either
heat or electricity.
15.2 Metals and metal alloys
An alloy is a solid mixture
of one or more elements.
Most metals are used as
alloys and not in their pure
elemental form.
Yellow brass is an alloy of
72% copper, 24% zinc, 3%
lead, and 1% tin.
15.2 Metals and metal alloys
Titanium combines the
strength and hardness
of steel with the light
weight of aluminum.
Titanium, a rare and
expensive alloy, is used
for military aircraft and
racing bicycles.
15.2 Carbon and carbon-like
elements
Almost all the molecules
that make up plants and
animals are constructed
around carbon.
The chemistry of carbon
is so important it has its
own name, organic
chemistry.
15.2 Carbon and carbon-like
elements
Pure carbon is found
in nature as either
graphite or diamond.
Why are carbon and
silicon important?
Silicon is the second
most abundant
element in the
Earth’s crust, second
only to oxygen.
15.2 Nitrogen, oxygen and
phosphorus
Oxygen and nitrogen are
crucial to living animals
and plants.
For example, proteins and
DNA both contain nitrogen.
Phosphorus is a key
ingredient of DNA, the
molecule responsible for
carrying the genetic code
in all living creatures.
15.2 Nitrogen, oxygen and
phosphorus
Proteins and DNA both
contain oxygen and
nitrogen, making these
elements crucial to life.
46% of the mass of
Earth’s crust is also
oxygen bound up in
rocks and minerals.
15.2 Nitrogen, oxygen and
phosphorus
Phosphorus is a key
ingredient of DNA, the
molecule responsible
for carrying the genetic
code in all living
creatures.
When phosphorus
atoms absorb light, they
store energy, then
release it in a greenish
glow.
Investigation 15C
Electrons and the Periodic Table
Key Question:
How do electrons fill up
the energy levels?
Silicon- The Super Element
Although silicon can form a
myriad of useful compounds,
it’s best known for its impact
on the modern world in the
form of the microchip, a
miniaturized electric circuit
that fits into computers,
cellular telephones,
microwaves, and other digital
appliances.