chapter menu section 3.1section 3.1development of the periodic table section 3.2 section 3.2 using...

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Section 3.1 Development of the Periodic Table

Section 3.2 Using the Periodic Table

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Section 3.1

Development of the Periodic Table

• Outline the steps in the historical development of the periodic table.

• Predict similarities in properties of the elements by using the periodic table.

Section 3.1


electron cloud: space around the nucleus of an atom where the atom’s electrons are found

Section 3.1


periodicity

periodic law

The periodic table evolved over time as scientists discovered more useful ways to compare and organize the elements.

Section 3.1

The Search for a Periodic Table

• Early scientists needed a system that would show similarities and differences between individual and groups of elements.

• J.W. Döbereiner classified some elements that had similar chemical properties into triads, organizing them according to their atomic mass.

Section 3.1

The Search for a Periodic Table (cont.)

Section 3.1


• Dmitri Mendeleev’s research revealed that the chemical and physical properties of the elements repeated in an orderly way when he organized the elements according to increasing atomic mass.

• Density, melting point, and boiling point all increase as atomic mass increases.

Section 3.1


Section 3.1


• By applying his theory of periodicity, or the tendency to recur at regular intervals, Mendeleev was able to predict properties of elements that had not yet been discovered.

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• Henry Moseley proposed rearranging the elements according to their atomic number, which resulted in the structure of the modern periodic table.

Section 3.1


Section 3.1

The Modern Periodic Table

• Each block of the modern periodic table shows the element’s name, symbol, atomic number, and atomic mass.

• At present, elements up to atomic number 118 have been discovered or synthesized.

• Atomic number increases by one as you move from element to element across a row.

Section 3.1

The Modern Periodic Table (cont.)

• With the exception of the first row, each row begins with a metal and ends with a noble gas.

• The idea that the physical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number is known as the modern periodic law.

Section 3.1

Section Assessment

The return of the full moon every 28 days is an example of ___.

A. phases

B. periodicity

C. frequency

D. periodic law

Section 3.1

Section Assessment

The most unreactive elements are found in which group?

A. 1

B. 2

C. 17

D. 18

End of Section 3.1

Section 3.2

Using the Periodic Table

• Relate an element’s valence electron structure to its position in the periodic table.

• Use the periodic table to classify an element as a metal, nonmetal, or metalloid.

• Compare the properties of metals, nonmetals, and metalloids.

Section 3.2


periodicity: the tendency to recur at regular intervals

Section 3.2


period

group

noble gas

metal

transition element

lanthanide

actinide

nonmetal

metalloid

semiconductor

Elements are organized in the periodic table according to their electron configurations.

Section 3.2

Relationship of the Periodic Table to Atomic Structure• Elements are organized in the periodic

table according to their electron configurations.

Section 3.2

Periods and Groups

• A period is a horizontal row on the periodic table.

• A group, or family, consists of elements in a vertical column of the periodic table.

Section 3.2

Periods and Groups (cont.)

• Group 18 elements, which have the maximum number of eight valence electrons and are generally unreactive, are known as the noble gases.

• The period number of an element is the same as the number of its outermost energy level.

Section 3.2


• The number of valence electrons changes from one to eight as you move from left to right across a period; when you get to group 18, the pattern repeats.

Section 3.2


• Because elements in the same group have the same number of valence electrons, they have similar properties.

Section 3.2


• Common names for some groups

– alkali metals in group 1

– alkaline earth metals in group 2

– chalcogens in group 16

– halogens in group 17

– noble gases in group 18

Section 3.2

Physical States and Classes of the Elements• Most elements are solid at room

temperature and normal atmospheric pressure.

• Synthetic elements are not found in nature but are produced artificially in particle accelerators.

Section 3.2

Physical States and Classes of the Elements (cont.)

• Elements are classified as metals, metalloids, or nonmetals on the basis of their physical and chemical properties.

Section 3.2


• Metals are elements that have luster, conduct heat and electricity, and usually bend without breaking.

– The majority of elements are metals.

– Most metals are solid at room temperature and have extremely high melting points.

– With the exception of tin, lead, and bismuth, metals have one, two, or three valence electrons.

Section 3.2


• The metals in groups 3 through 12 of the periodic table are called the transition elements.

• The unpredictable behavior and properties of the transition metals is due to the more complicated atomic structure of these elements.

Section 3.2


• The transition elements are divided into transition metals and inner transition metals.

• The two sets of inner transition metals are called the lanthanide series and actinide series and are located at the bottom of the periodic table.

Section 3.2


• Nonmetals are elements that are generally gases or brittle, dull-looking solids, and poor conductors of heat and electricity.

Section 3.2


• Metalloids have physical and chemical properties of both metals and nonmetals, such as silicon and germanium.

• Some metalloids are semiconductors, or an element that does not conduct electricity as well as a metal but does conduct slightly better than a nonmetal.

Section 3.2


• When undergoing chemical reactions, metals tend to lose valence electrons, whereas nonmetals tend to share electrons or gain electrons from other atoms.

Section 3.2

Semiconductors and Their Uses

• Most metals conduct an electric current because their valence electrons are not held tightly by the positive nucleus and are free to move.

Section 3.2

Semiconductors and Their Uses (cont.)

• The electrical conductivity of a semiconductor such as silicon can be increased by a process known as doping—the addition of a small amount of another element to a crystal of a semiconductor.

– n-type semiconductor

– p-type semiconductor

Section 3.2


Section 3.2


• Many semiconductors are made by combining n- and p-type semiconductors to form a diode.

• Transistors, diodes, and other semiconductors are incorporated into thin slices of silicon to form integrated circuits and are widely used in the development of technology.

Section 3.2

Section Assessment

An element with a full octet has how many valence electrons?

A. two

B. six

C. eight

D. ten

Section 3.2

Section Assessment

The actinide series is part of the:

A. s-block elements

B. inner transition metals

C. nonmetals

D. alkali metals

Study Guide 1

Key Concepts

• In his periodic table, Mendeleev organized the elements according to increasing atomic mass and placed elements with similar properties into groups.

• The modern periodic law states that the physical and chemical properties of the elements repeat in a regular pattern when they are arranged in order of increasing atomic number.

Study Guide 2

Key Concepts

• Atomic structure and the number of valence electrons can be related to an element’s position on the periodic table.

• Elements are classified as metals, nonmetals, or metalloids.

• The number of valence electrons and how tightly they are held determine the chemical properties of an element.

• The conductivity of semiconductors can be increased by adding small amounts of other elements.

Chapter Assessment 1

Which chemist used triads to organize elements?

A. Döbereiner

B. Mendeleev

C. Moseley

D. Curie


Elements are organized in the periodic table according to their ___ configurations.

A. electron

B. proton

C. neutron

D. atomic


What is a row of elements on the periodic table called?

A. octave

B. period

C. group

D. transition


At room temperature and in normal atmospheric pressure, most elements are ___.

A. gases

B. liquids

C. solids


By which method are synthetic elements created?

A. nuclear reactions

B. splitting electrons

C. chemical reactions

D. splitting neutrons

STP 1

The majority of elements are ___.

A. synthetic

B. metalloids

C. nonmetals

D. metals

STP 2

Which element is a transition element?

A. nickel

B. zinc

C. tin

D. lead

STP 3

Which elements are sometimes called the rare earth elements?

A. actinides

B. lanthanides

C. noble gases

D. metalloids

STP 4

Which group of elements are the least reactive?

A. alkali metals

B. inner transition metals

C. halogens

D. noble gases

STP 5

What is silicon an example of?

A. metal

B. nonmetal

C. metalloid

D. inner transition metal

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chapter menu section 3.1section 3.1development of the periodic table section 3.2 section 3.2 using...

Documents

periodic table section

modern periodic table

periodic law slide

periodic table electron

section assessment

modern periodic law

end of section

periodicity slide