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THE PERIODIC TABLEChapter 7
THE PERIODIC TABLE
Lesson 1Using the Periodic Table Lesson 2Metals Lesson 3Nonmetals and Metalloids
LESSON 1: USING THE PERIODIC TABLE Key Concepts
How are elements arranged on the periodic table? What can you learn about elements from the
periodic table?
LESSON 1: USING THE PERIODIC TABLE What is the periodic table?
The periodic table is a chart of the elements arranged into rows and columns according to their physical and chemical properties.
It can be used to determine the relationships among the elements.
LESSON 1: USING THE PERIODIC TABLE Developing a periodic table
When Russian chemist Dimitri Mendeleev was working on classifying the elements, he placed his list of elements into a table and arranged them in rows of increasing atomic mass.
Elements with similar properties were grouped in the same column.
LESSON 1: USING THE PERIODIC TABLE
Mendeleev noticed that melting point is one property that shows a repeating pattern.
LESSON 1: USING THE PERIODIC TABLE Developing a periodic table (cont.)
Boiling point and reactivity also follow a periodic pattern.
Mendeleev believed that the atomic masses of certain elements must be invalid because the elements appeared in the wrong place on the periodic table.
He placed elements whose properties resembled each other’s closer together in the table.
LESSON 1: USING THE PERIODIC TABLE
When Moseley listed the elements according to atomic number, columns contained elements with similar properties, such as copper, silver, and gold.
LESSON 1: USING THE PERIODIC TABLE Today’s periodic table
You can identify many of the properties of an element from its placement on the periodic table.
periodScience Use the completion of a cycle; a row on the periodic tableCommon Use a point used to mark the end of a sentence; a time frame
LESSON 1: USING THE PERIODIC TABLE
The table is organized into columns, rows, and blocks, which are based on certain patterns of properties.
LESSON 1: USING THE PERIODIC TABLE Today’s periodic table (cont.)
The element key shows an element’s chemical symbol, atomic number, and atomic mass.
The key also contains a symbol that shows the state of matter at room temperature.
LESSON 1: USING THE PERIODIC TABLE Today’s periodic table (cont.)
A group is a column on the periodic table. Elements in the same group have similar
chemical properties and react with other elements in similar ways.
LESSON 1: USING THE PERIODIC TABLE Today’s periodic table (cont.)
The rows on the periodic table are called periods.
The atomic number of each element increases by one as you read from left to right across each period.
LESSON 1: USING THE PERIODIC TABLE Today’s periodic table
Metals are on the left side and in the middle of the periodic table.
With the exception of hydrogen, nonmetals are located on the right side of the periodic table.
Between the metals and the nonmetals on the periodic table are the metalloids.
LESSON 1: USING THE PERIODIC TABLE How scientists use the periodic table
Even today, new elements are created in laboratories, named, and added to the present-day periodic table.
LESSON 1: USING THE PERIODIC TABLE How scientists use the periodic table
(cont.) Scientists can use the periodic table to
predict the properties of new elements they create.
The periodic table contains more than 100 elements, each with its unique properties that differ from the properties of other elements.
LESSON 1: USING THE PERIODIC TABLE Summary
On the periodic table, elements are arranged according to increasing atomic numbers and similar properties.
A column of the periodic table is called a group. Elements in the same group have similar properties.
A row of the periodic table is called a period. Properties of elements repeat in the same pattern from left to right across each period.
LESSON 2: METALS
Key Concepts What elements are metals? What are the properties of metals?
LESSON 2: METALS
What is a metal? More than three-quarters of the elements
on the periodic table are metals. With the exception of hydrogen, all of the
elements in groups 1-12 on the periodic table are metals.
Some of the elements in groups 13-15 are metals.
To be a metal, an element must have certain properties.
LESSON 2: METALS
What is a metal? (cont.) A metal is an element that is generally
shiny. It is easily pulled into wires or hammered into thin sheets. A metal is a good conductor of electricity and thermal energy.
Luster describes the ability of a metal to reflect light.
Ductility is the ability to be pulled into
thin wires.
LESSON 2: METALS
What is a metal? (cont.) Malleability is the ability of a substance
to be hammered or rolled into sheets. Gold is so malleable that it can be
hammered into thin sheets. In general the density, strength, boiling
point, and melting point of a metal are greater than those of other elements.
LESSON 2: METALS
Group 1: Alkali Metals The elements in group 1 are called alkali
metals. The alkali metals include lithium, sodium,
potassium, rubidium, cesium, and francium. Alkali metals react quickly with other elements,
such as oxygen and in nature, occur only in compounds.
Alkali metals react violently with water. They are also soft enough to be cut with a knife.
LESSON 2: METALS
Group 2: Alkaline Earth Metals The elements in group 2 on the periodic table
are called alkaline earth metals. The alkaline earth metals are beryllium,
magnesium, calcium, strontium, barium, and radium.
Pure alkaline earth metals do not occur naturally but instead combine with other elements and form compounds.
LESSON 2: METALS
Groups 3-12: Transition Elements The elements in groups 3-12 are called
transition elements. Transition elements are in a block at the
center and two rows at the bottom of the periodic table.
Many colorful materials contain small amounts of transition elements.
LESSON 2: METALS
Groups 3-12: Transition Elements (cont.) All transition elements are metals with higher
melting points, greater strength, and higher densities than the alkali metals and the alkaline earth metals.
Because of their high densities, strength, and resistance to corrosion, transition elements make good building materials.
Two rows of transition elements—the lanthanide and actinide series—were removed from the main part of the table so that periods 6 and 7 were not longer than the other periods.
LESSON 2: METALS
Patterns in properties of metals Metallic properties include luster,
malleability, and electrical conductivity.
LESSON 2: METALS
Summary Properties of metals include conductivity,
luster, malleability, and ductility. Alkali metals and alkaline earth metals
react easily with other elements. These metals make up groups 1 and 2 on the periodic table.
Transition elements make up groups 3-12 and the lanthanide and actinide series on the periodic table.
LESSON 3: METALS AND METALLOIDS Key Concepts
Where are nonmetals and metalloids on the periodic table?
What are the properties of nonmetals and metalloids?
LESSON 3: METALS AND METALLOIDS The elements of life
More than 96 percent of the mass of the human body comes from four nonmetals–oxygen, carbon, hydrogen, and nitrogen.
LESSON 3: METALS AND METALLOIDS The elements of life (cont.)
Nonmetals are elements that have no metallic properties.
The four elements that make up most of the human body, along with phosphorus and sulfur, are the six elements in proteins, fats, nucleic acids, and other large molecules in your body and in all other living things.
LESSON 3: METALS AND METALLOIDS How are nonmetals different from metals?
Nonmetals have properties that are different from those of metals.
Many nonmetals are gases at room temperature and those that are solid at room temperature have a dull surface, which means they have no luster.
Because nonmetals are poor conductors of electricity and thermal energy, they are good insulators.
LESSON 3: METALS AND METALLOIDS
Phosphorus and carbon are dull, brittle solids that do not conduct thermal energy or electricity.
LESSON 3: METALS AND METALLOIDS How are nonmetals different from
metals? (cont.) An element in group 17 of the periodic
table is galled a halogen. The term halogen refers to an element that
can react with a metal and form a salt.
LESSON 3: METALS AND METALLOIDS How are nonmetals different from metals?
(cont.) Halogens react readily with other elements and
form compounds. Halogens can only occur naturally in compounds. In general, halogens are less reactive as you move
down the group. The elements in group 18 are known as the noble
gases.
LESSON 3: METALS AND METALLOIDS How are nonmetals different from metals? (cont.)
Unlike the halogens, the only way elements in this group react with other elements is under special conditions in a laboratory.
Of all the elements, hydrogen has the smallest atomic mass and is the most common element in the universe.
Hydrogen is most often classified as a nonmetal because it has many properties like those of nonmetals.
However, hydrogen also has some properties similar to those of the group 1 alkali metals.
Under conditions on Earth, hydrogen usually behaves as a nonmetal.
LESSON 3: METALS AND METALLOIDS Metalloids
Between the metals and the nonmetals on the periodic table are elements known as metalloids.
LESSON 3: METALS AND METALLOIDS Metalloids (cont.)
A metalloid is an element that has physical and chemical properties of both metals and nonmetals.
The elements boron, silicon, germanium, arsenic, antimony, tellurium, polonium, and astatine are metalloids.
Silicon is the most abundant metalloid in the universe.
LESSON 3: METALS AND METALLOIDS Metalloids (cont.)
A property of metalloids is the ability to act as a semiconductor.
A semiconductor conducts electricity at high temperatures, but not at low temperatures.
Silicon is used in making semiconductor devices for computers and other electronic products.
LESSON 3: METALS AND METALLOIDS Metals, nonmetals, and metalloids
An element’s position on the periodic table tells you a lot about the element.
Understanding the properties of elements can help you decide which element to use in a given situation.
LESSON 3: METALS AND METALLOIDS Summary
A nonmetal is an element that has no metallic properties. Solid nonmetals are dull and brittle and do not conduct thermal energy or electricity.
Halogens and noble gases are nonmetals. These elements are found in group 17 and group 18 of the periodic table.
Metalloids have some metallic properties and some nonmetallic properties. The most important use of metalloids is as semiconductors.
CHAPTER WRAP-UP
Lesson 1: Using the Periodic Table Elements are organized on the periodic table by
increasing atomic number and similar properties.
Elements in the same group, or column, of the periodic table have similar properties.
Elements’ properties change across a period, which is a row of the periodic table.
Each element key on the periodic table provides the name, symbol, atomic number, and atomic mass for an element.
CHAPTER WRAP-UP
Lesson 2: Metals Metals are located on the left and middle
parts of the periodic table. Metals are elements that have ductility,
malleability, luster, and conductivity. The alkali metals are in group 1 of the
periodic table, and the alkaline earth metals are in group 2.
Transition elements are metals in groups 3-12 of the periodic table, as well as the lanthanide and actinide series.
CHAPTER WRAP-UP Lesson 3: Nonmetals
and Metalloids Nonmetals are on the
right side of the periodic table, and metalloids are located between metals and nonmetals.
Nonmetals are elements that have no metallic properties. Solid nonmetals are dull in appearance, brittle, and do not conduct electricity. Metalloids are elements that have properties of both metals and nonmetals.
Some metalloids are semiconductors. Elements in group 17 are called halogens, and
elements in group 18 are noble gases.
