organizing the elements

© Copyright Pearson Prentice Hall

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6.1 Organizing the Elements

In a self-service store, the products are grouped according to similar characteristics. With a logical classification system, finding and comparing products is easy. You will learn how elements are arranged in the periodic table and what that arrangement reveals about the elements.


Organizing the Elements >

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Searching For an Organizing Principle

Searching For an Organizing Principle

How did chemists begin to organize the known elements?

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Organizing the Elements > Searching For an Organizing Principle

Chemists used the properties of elements to sort them into groups.

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Organizing the Elements > Searching For an Organizing Principle

Chlorine, bromine, and iodine have very similar chemical properties.

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Mendeleev’s Periodic Table

Mendeleev’s Periodic Table

How did Mendeleev organize his periodic table?

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Organizing the Elements > Mendeleev’s Periodic Table

Mendeleev arranged the elements in his periodic table in order of increasing atomic mass.

The periodic table can be used to predict the properties of undiscovered elements.

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Organizing the Elements > Mendeleev’s Periodic Table

An Early Version of Mendeleev’s Periodic Table

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The Periodic Law

The Periodic Law

How is the modern periodic table organized?

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Organizing the Elements > The Periodic Law

In the modern periodic table, elements are arranged in order of increasing atomic number.

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Organizing the Elements > The Periodic Law

The periodic law: When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.

• The properties of the elements within a period change as you move across a period from left to right.

• The pattern of properties within a period repeats as you move from one period to the next.

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Metals, Nonmetals, and Metalloids

Metals, Nonmetals, and Metalloids

What are three broad classes of elements?

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Organizing the Elements > Metals, Nonmetals, and Metalloids

Three classes of elements are metals, nonmetals, and metalloids.

Across a period, the properties of elements become less metallic and more nonmetallic.

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Metals, Metalloids, and Nonmetals in the Periodic Table

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Metals

Metals are good conductors of heat and electric current.

• 80% of elements are metals.

• Metals have a high luster, are ductile, and are malleable.

• Have only a few electrons in their outer shell

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Uses of Iron, Copper, and Aluminum

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Nonmetals

In general, nonmetals are poor conductors of heat and electric current.

• Most nonmetals are gases at room temperature.

• A few nonmetals are solids, such as sulfur and phosphorus.

• One nonmetal, bromine, is a dark-red liquid.

• Usually have more than 3 electrons in their outer shell.

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Metalloids

A metalloid generally has properties that are similar to those of metals and nonmetals.

The behavior of a metalloid can be controlled by changing conditions.

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If a small amount of boron is mixed with silicon, the mixture is a good conductor of electric current. Silicon can be cut into wafers, and used to make computer chips.

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1. The modern periodic table has elements arranged in order of

a. colors.

b. melting and boiling points.

c. increasing atomic mass.

d. increasing atomic number.

6.1 Section Quiz


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2. Mendeleev arranged the elements in his periodic table in order of increasing

a. atomic number.

b. number of protons.

c. number of electrons.

d. atomic mass

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3. Which one of the following is NOT a general property of metals?

a. ductility

b. malleability

c. having a high luster

d. poor conductor of heat and electricity

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6.2 Squares in the Periodic Table

Squares in the Periodic Table

What type of information can be displayed in a periodic table?


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a. The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms.

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a. The background colors in the squares are used to distinguish groups of elements.

The Group 1A elements are called alkali metals.

The Group 2A elements are called alkaline earth metals.

Group 6A elements are called the chalcogens.

The nonmetals of Group 7A are called halogens.

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Squares in the Periodic Table6.2


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Electron Configurations in Groups


How can elements be classified based on their electron configurations?

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a. Elements can be sorted into noble gases, representative elements, transition metals, or inner transition metals based on their electron configurations.

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a. The blimp contains helium, one of the noble gases.

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The Noble Gases

a. The noble gases are the elements in Group 8A of the periodic table. The electron configurations for the first four noble gases in Group 8A are listed below.

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The Representative Elements

a. Elements in groups 1A through 7A are often referred to as representative elements because they display a wide range of physical and chemical properties.

The s and p sublevels of the highest occupied energy level are not filled.

The group number equals the number of electrons in the highest occupied energy level.

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a. In atoms of the Group 1A elements below, there is only one electron in the highest occupied energy level.

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a. In atoms of the Group 4A elements below, there are four electrons in the highest occupied energy level.

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Representative Elements

a. Representative Elements

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Transition Elements

Transition Elements

a. There are two types of transition elements—transition metals and inner transition metals. They are classified based on their electron configurations.

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Transition Elements

a. In atoms of a transition metal, the highest occupied s sublevel and a nearby d sublevel contain electrons.

b. In atoms of an inner transition metal, the highest occupied s sublevel and a nearby f sublevel generally contain electrons.

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Transition Elements

Blocks of Elements

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6.2 Section Quiz

1. Which of the following information about elements is usually NOT included in a periodic table?

a. color

b. symbol

c. atomic number

d. atomic mass


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6.2 Section Quiz

2. An alkali metal would have in the highest occupied energy level

a. an s2 electron.

b. an s1 electron.

c. p2 electrons.

d. p6 electrons.


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3. Which one of the following is incorrectly labeled?

a. Ne, noble gas

b. Cu, transition metal

c. Ga, transition metal

d. Cl, halogen

6.2 Section Quiz


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6.2 Section Quiz

4. Transition metals are characterized as being different than representative elements because they have electrons in which suborbitals?

a. p

b. d

c. s

d. f


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Periodic Trends

Sodium chloride (table salt) produced the geometric pattern in the photograph. Such a pattern can be used to calculate the position of nuclei in a solid. You will learn how properties such as atomic size are related to the location of elements in the periodic table.

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Trends in Atomic Size


What are the trends among the elements for atomic size?

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The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined.

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Group and Periodic Trends in Atomic Size

In general, atomic size increases from top to bottom within a group and decreases from left to right across a period.

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Trends in Atomic Size6.3


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Trends in Atomic Size6.3


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Ions

Ions

How do ions form?

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Ions

a.Positive and negative ions form when electrons are transferred between atoms.

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Ions

a.Positive and negative ions form when electrons are transferred between atoms.

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Ions

a. Some compounds are composed of particles called ions.

An ion is an atom or group of atoms that has a positive or negative charge.

A cation is an ion with a positive charge.

An anion is an ion with a negative charge.

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Trends in Ionization Energy


What are the trends among the elements for first ionization energy, ionic size, and electronegativity?

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a. The energy required to remove an electron from an atom is called ionization energy.

The energy required to remove the first electron from an atom is called the first ionization energy.

The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy.

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Group and Periodic Trends in Ionization Energy

a. First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.

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Trends in Ionization Energy6.3


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Trends in Ionic Size


a. During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form.

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a. Cations are always smaller than the atoms from which they form. Anions are always larger than the atoms from which they form.

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a. Relative Sizes of Some Atoms and Ions

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a. Trends in Ionic Size

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Trends in Electronegativity


a. Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound.

In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period.

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Representative Elements in Groups 1A through 7A

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Summary of Trends

Summary of Trends

What is the underlying cause of periodic trends?

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Summary of Trends

a. The trends that exist among these properties can be explained by variations in atomic structure.

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1. Which of the following sequences is correct for atomic size?

a. Mg > Al > S

b. Li > Na > K

c. F > N > B

d. F > Cl > Br

6.3 Section Quiz


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6.3 Section Quiz

2. Metals tend to

a. gain electrons to form cations.

b. gain electrons to form anions.

c. lose electrons to form anions.

d. lose electrons to form cations.


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6.3 Section Quiz

3. Which of the following is the most electronegative?

a. Cl

b. Se

c. Na

d. I


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organizing the elements

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