The Modern Periodic Table The modern periodic table

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

The Modern Periodic Table (cont. ) • 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. ) • 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. • Non-metals are elements that are generally gases or brittle, dull-looking solids, and poor conductors of heat and electricity. • Metalloids have physical and chemical properties of both metals and non-metals, such as silicon and germanium.

Group 1: Alkali Metals • Hydrogen is not a member, it is a non-metal • 1 electron in the outer shell • Soft and silvery metals • Very reactive, esp. with water • Conduct electricity

• Group 2: Alkaline Earth Metals • 2 electrons in the outer shell • White and malleable • Reactive, but less than Alkali metals • Conduct electricity

The Modern Periodic Table (cont. ) • 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.

Group 13 (3 A) • BORON/ALUMINUM FAMILY • 3 electrons in the outer shell • Most are metals • Boron is a metalloid

• CARBON FAMILY Group 14 (4 A) • 4 electrons in the outer shell • Contains metals, metalloids, and a nonmetal Carbon (C)

• NITROGEN FAMILY Group 15 (5 A) • 5 electrons in the outer shell • Can share electrons to form compounds • Contains metals, metalloids, and nonmetals

• OXYGEN FAMILY Group 16 (6 A) • 6 electrons in the outer shell • Contains metals, metalloids, and nonmetals • Reactive

Halogens Group 17 (7 A) • 7 electrons in the outer shell • All are non-metals • Very reactive are often bonded with elements from Group 1

Noble Gases Group 18 (8 A) • Exist as gases • Non-metals • 8 electrons in the outer shell = Full • Helium (He) has only 2 electrons in the outer shell = Full • Not reactive with other elements

The Modern Periodic Table (cont. )

Section 6. 1 Assessment What is a row of elements on the periodic table called? A. octave B. period C. group D. transition A. B. C. D. A B C D

Section 6. 1 Assessment What is silicon an example of? A. metal B. non-metal C. inner transition metal D. metalloid A. B. C. D. A B C D

Organizing the Elements by Electron Configuration • Recall electrons in the highest principal energy level are called valence electrons. • All group 1 elements have one valence electron.

Organizing the Elements by Electron Configuration (cont. ) • 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.

Organizing the Elements by Electron Configuration (cont. )

The s-, p-, d-, and f-Block Elements (cont. ) • 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 • 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 (cont. ) • After the s-orbital is filled, valence electrons occupy the p-orbital. • Groups 13 -18 contain elements with completely or partially filled p orbitals.

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

The s-, p-, d-, and f-Block Elements (cont. ) • The f-block contains the inner transition metals. • f-block elements have filled or partially filled outermost s orbitals and filled or partially filled 4 f and 5 f orbitals. • The 7 f orbitals hold 14 electrons, and the inner transition metals span 14 groups.

Section 6. 2 Assessment 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 A. B. C. D. A B C D

Section 6. 2 Assessment Which block spans 14 elemental groups? A. s-block B. p-block C. f-block D. g-block A. B. C. D. A B C D

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

Development of the Periodic Table (cont. ) • The 1800 s 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. ) • Newlands noticed when the elements were arranged by increasing atomic mass, their properties repeated every eighth element.

Development of the Periodic Table (cont. ) • 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.

Development of the Periodic Table (cont. )

Atomic Radius • 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.

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

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.

Atomic Radius (cont. )

Atomic Radius (cont. ) • Atomic radius generally increases as you move down a group. • The outermost orbital size increases down a group, making the atom larger.

Ionic Radius • 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.

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

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.

Ionic Radius (cont. ) • Both positive and negative ions increase in size moving down a group.

Ionization Energy • 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.

Ionization Energy (cont. )

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.

Ionization Energy (cont. )

Ionization Energy (cont. ) • 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.

Ionization Energy (cont. )

Ionization Energy (cont. ) • 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.

Ionization Energy (cont. ) • 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.

Ionization Energy (cont. )

Section 6. 3 Assessment The lowest ionization energy is the ____. A. first B. second C. third D. fourth A. B. C. D. A B C D

Section 6. 3 Assessment 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 A. B. C. D. A B C D

Chemistry Online Study Guide Chapter Assessment Standardized Test Practice Image Bank Concepts in Motion

Section 6. 1 Development of the Modern Periodic Table 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.

Section 6. 1 Development of the Modern Periodic Table (contd. ) Key Concepts • Elements are classified as either metals, nonmetals, or metalloids.

Section 6. 2 Classification of the Elements 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.

Section 6. 3 Periodic Trends 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.

The actinide series is part of the A. s-block elements. B. inner transition metals. C. non-metals. D. alkali metals. A. B. C. D. A B C D

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 A. B. C. D. A B C D

Which block contains the transition metals? A. s-block B. p-block C. d-block D. f-block A. B. C. D. A B C D

An element with a full octet has how many valence electrons? A. two B. six C. eight D. ten A. B. C. D. A B C D

How many groups of elements are there? A. 8 B. 16 C. 18 D. 4 A. B. C. D. A B C D

Which group of elements are the least reactive? A. alkali metals B. inner transition metals C. halogens D. noble gases A. B. C. D. A B C D

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 A. B. C. D. A B C D

Unreactive gases are mostly found where on the periodic table? A. halogens B. group 1 and 2 C. group 18 D. f-block A. B. C. D. A B C D

Bromine is a member of the A. noble gases. B. inner transition metals. C. earth metals. D. halogens. A. B. C. D. A B C D

How many groups does the d-block span? A. two B. six C. ten D. fourteen A. B. C. D. A B C D

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Table 6. 4 Noble Gas Electron Configuration Figure 6. 5 The Periodic Table Figure 6. 11 Trends in Atomic Radii Figure 6. 18 Trends in Electronegativity

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