Chapter 6: The Periodic Table and Periodic Law CHEMISTRY Matter and Change.

Chapter 6: The Periodic Table and Periodic LawChapter 6: The Periodic Table and Periodic Law

CHEMISTRY Matter and Change

Section 6.1 Development of the Modern Periodic Table

Section 6.2 Classification of the Elements

Section 6.3 Periodic Trends

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Table Of ContentsCHAPTER

6

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• Trace the development of the periodic table.

atomic number: the number of protons in an atom

• Identify key features of the periodic table.

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

SECTION6.1

Development of the Modern Periodic Table

periodic law

group

period

representative elements

transition elements

metal

alkali metals

alkaline earth metals

transition metal

inner transition metal

lanthanide series

actinide series

nonmetals

halogen

noble gas

metalloid

SECTION6.1


• In the 1700s, Lavoisier compiled a list of all the known elements of the time.

Development of the Periodic Table

SECTION6.1


• The 1800s brought large amounts of information and scientists needed a way to organize knowledge about elements.

• John Newlands proposed an arrangement where elements were ordered by increasing atomic mass.

Development of the Periodic Table (cont.)

SECTION6.1


• Newlands noticed when the elements were arranged by increasing atomic mass, their properties repeated every eighth element.


SECTION6.1


• Meyer and Mendeleev both demonstrated a connection between atomic mass and elemental properties.

• Moseley rearranged the table by increasing atomic number, and resulted in a clear periodic pattern.

• Periodic repetition of chemical and physical properties of the elements when they are arranged by increasing atomic number is called periodic law.


SECTION6.1



SECTION6.1


• The modern periodic table contains boxes which contain the element's name, symbol, atomic number, and atomic mass.

The Modern Periodic Table

SECTION6.1


• Columns of elements are called groups.

• Rows of elements are called periods.

• Elements in groups 1,2, and 13-18 possess a wide variety of chemical and physical properties and are called the representative elements.

• Elements in groups 3-12 are known as the transition metals.

The Modern Periodic Table (cont.)

SECTION6.1


• Elements are classified as metals, non-metals, and metalloids.

• Metals are elements that are generally shiny when smooth and clean, solid at room temperature, and good conductors of heat and electricity.

• Alkali metals are all the elements in group 1 except hydrogen, and are very reactive.

• Alkaline earth metals are in group 2, and are also highly reactive.


SECTION6.1


• 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.


SECTION6.1


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

• Group 17 is composed of highly reactive elements called halogens.

• Group 18 gases are extremely unreactive and commonly called noble gases.


SECTION6.1


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


SECTION6.1



SECTION6.1


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

A. octave

B. period

C. group

D. transition

SECTION6.1

Section Check

What is silicon an example of?

A. metal

B. non-metal

C. inner transition metal

D. metalloid

SECTION6.1

Section Check

• Explain why elements in the same group have similar properties.

valence electron: electron in an atom's outermost orbitals; determines the chemical properties of an atom• Identify the four blocks

of the periodic table based on their electron configuration.

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

SECTION6.2

Classification of the Elements

• Recall electrons in the highest principal energy level are called valence electrons.

• All group 1 elements have one valence electron.

SECTION6.2


Organizing the Elements by Electron Configuration

• The energy level of an element’s valence electrons indicates the period on the periodic table in which it is found.

• The number of valence electrons for elements in groups 13-18 is ten less than their group number.

SECTION6.2


Organizing the Elements by Electron Configuration (cont.)

SECTION6.2


Organizing the Elements by Electron Configuration (cont.)

• The shape of the periodic table becomes clear if it is divided into blocks representing the atom’s energy sublevel being filled with valence electrons.


The s-, p-, d-, and f-Block Elements

SECTION6.2

• s-block elements consist of group 1 and 2, and the element helium.

• Group 1 elements have a partially filled s orbital with one electron.

• Group 2 elements have a completely filled s orbital with two electrons.


The s-, p-, d-, and f-Block Elements (cont.)

SECTION6.2

• After the s-orbital is filled, valence electrons occupy the p-orbital.

• Groups 13-18 contain elements with completely or partially filled p orbitals.

SECTION6.2



• The d-block contains the transition metals and is the largest block.

• There are exceptions, but d-block elements usually have filled outermost s orbital, and filled or partially filled d orbital.

• The five d orbitals can hold 10 electrons, so the d-block spans ten groups on the periodic table.

Classification of the ElementsSECTION6.2


• The f-block contains the inner transition metals.

• f-block elements have filled or partially filled outermost s orbitals and filled or partially filled 4f and 5f orbitals.

• The 7 f orbitals hold 14 electrons, and the inner transition metals span 14 groups.

SECTION6.2



Which of the following is NOT one of the elemental blocks of the periodic table?

A. s-block

B. d-block

C. g-block

D. f-block

SECTION6.2

Section Check

Which block spans 14 elemental groups?

A. s-block

B. p-block

C. f-block

D. g-block

SECTION6.2

Section Check

• Compare period and group trends of several properties.

principal energy level: the major energy level of an atom

ion

ionization energy

octet rule

electronegativity

• Relate period and group trends in atomic radii to electron configuration.

Trends among elements in the periodic table include their size and their ability to lose or attract electrons

SECTION6.3

Periodic Trends

• Atomic size is a periodic trend influenced by electron configuration.

• For metals, atomic radius is half the distance between adjacent nuclei in a crystal of the element.

SECTION6.3

Periodic Trends

Atomic Radius

• For elements that occur as molecules, the atomic radius is half the distance between nuclei of identical atoms.

SECTION6.3

Periodic Trends

Atomic Radius (cont.)

• There is a general decrease in atomic radius from left to right, caused by increasing positive charge in the nucleus.

• Valence electrons are not shielded from the increasing nuclear charge because no additional electrons come between the nucleus and the valence electrons.

SECTION6.3

Periodic Trends


SECTION6.3

Periodic Trends


• Atomic radius generally increases as you move down a group.

• The outermost orbital size increases down a group, making the atom larger.

SECTION6.3

Periodic Trends


• An ion is an atom or bonded group of atoms with a positive or negative charge.

• When atoms lose electrons and form positively charged ions, they always become smaller for two reasons:

1. The loss of a valence electron can leave an empty outer orbital resulting in a small radius.

2. Electrostatic repulsion decreases allowing the electrons to be pulled closer to the radius.

SECTION6.3

Periodic Trends

Ionic Radius

• When atoms gain electrons, they can become larger, because the addition of an electron increases electrostatic repulsion.

SECTION6.3

Periodic Trends

Ionic Radius (cont.)

• The ionic radii of positive ions generally decrease from left to right.

• The ionic radii of negative ions generally decrease from left to right, beginning with group 15 or 16.

SECTION6.3

Periodic Trends


• Both positive and negative ions increase in size moving down a group.

SECTION6.3

Periodic Trends


• Ionization energy is defined as the energy required to remove an electron from a gaseous atom.

• The energy required to remove the first electron is called the first ionization energy.

SECTION6.3

Periodic Trends

Ionization Energy

SECTION6.3

Periodic Trends

Ionization Energy (cont.)

• Removing the second electron requires more energy, and is called the second ionization energy.

• Each successive ionization requires more energy, but it is not a steady increase.

SECTION6.3

Periodic Trends


Periodic TrendsSECTION6.3



• The ionization at which the large increase in energy occurs is related to the number of valence electrons.

• First ionization energy increases from left to right across a period.

• First ionization energy decreases down a group because atomic size increases and less energy is required to remove an electron farther from the nucleus.

SECTION6.3

Periodic Trends


SECTION6.3

Periodic Trends


• The octet rule states that atoms tend to gain, lose or share electrons in order to acquire a full set of eight valence electrons.

• The octet rule is useful for predicting what types of ions an element is likely to form.

SECTION6.3

Periodic Trends

• The electronegativity of an element indicates its relative ability to attract electrons in a chemical bond.

• Electronegativity decreases down a group and increases left to right across a period.

SECTION6.3

Periodic Trends


SECTION6.3

Periodic Trends


The lowest ionization energy is the ____.

A. first

B. second

C. third

D. fourth

SECTION6.3

Section Check

The ionic radius of a negative ion becomes larger when:

A. moving up a group

B. moving right to left across period

C. moving down a group

D. the ion loses electrons

SECTION6.3

Section Check

Chemistry Online

Study Guide

Chapter Assessment

Standardized Test Practice

Resources

The Periodic Table and Periodic LawCHAPTER

6

Key Concepts

• The elements were first organized by increasing atomic mass, which led to inconsistencies. Later, they were organized by increasing atomic number.

• The periodic law states that when the elements are arranged by increasing atomic number, there is a periodic repetition of their chemical and physical properties.

• The periodic table organizes the elements into periods (rows) and groups (columns); elements with similar properties are in the same group.

Study Guide

SECTION6.1


Key Concepts

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

Study Guide

SECTION6.1


Key Concepts

• The periodic table has four blocks (s, p, d, f).

• Elements within a group have similar chemical properties.

• The group number for elements in groups 1 and 2 equals the element’s number of valence electrons.

• The energy level of an atom’s valence electrons equals its period number.

Study Guide

Classification of the ElementsSECTION6.2

Key Concepts• Atomic and ionic radii decrease from left to right across

a period, and increase as you move down a group.

• Ionization energies generally increase from left to right across a period, and decrease as you move down a group.

• The octet rule states that atoms gain, lose, or share electrons to acquire a full set of eight valence electrons.

• Electronegativity generally increases from left to right across a period, and decreases as you move down a group.

Study Guide

Periodic TrendsSECTION6.3

The actinide series is part of the

A. s-block elements.

B. inner transition metals.

C. non-metals.

D. alkali metals.

The Periodic Table and Periodic Law

Chapter Assessment

CHAPTER

6

In their elemental state, which group has a complete octet of valence electrons?

A. alkali metals

B. alkaline earth metals

C. halogens

D. noble gases


Chapter Assessment

CHAPTER

6

Which block contains the transition metals?

A. s-block

B. p-block

C. d-block

D. f-block


Chapter Assessment

CHAPTER

6

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

A. two

B. six

C. eight

D. ten

CHAPTER

6 The Periodic Table and Periodic Law

Chapter Assessment

How many groups of elements are there?

A. 8

B. 16

C. 18

D. 4

The Periodic Table and Periodic LawCHAPTER

6

Chapter Assessment

Which group of elements are the least reactive?

A. alkali metals

B. inner transition metals

C. halogens

D. noble gases

CHAPTER

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On the modern periodic table, alkaline earth metals are found only in ____.

A. group 1

B. s-block

C. p-block

D. groups 13–18

CHAPTER

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Unreactive gases are mostly found where on the periodic table?

A. halogens

B. group 1 and 2

C. group 18

D. f-block

CHAPTER

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Bromine is a member of the

A. noble gases.

B. inner transition metals.

C. earth metals.

D. halogens.

CHAPTER

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How many groups does the d-block span?

A. two

B. six

C. ten

D. fourteen

CHAPTER

6



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Chapter 6: The Periodic Table and Periodic Law CHEMISTRY Matter and Change.

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