The Periodic TableChapter 6

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.

Searching For an Organizing Principle

Searching For an Organizing Principle◦ How did chemists begin to organize the known

elements? Chemists used the properties of elements to sort

them into groups (vertical columns).

6.1

Searching For an Organizing Principle

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

6.1

Mendeleev’s Periodic Table Mendeleev’s Periodic Table

◦ How did Mendeleev organize his periodic table? Mendeleev organized elements into groups based on

a set of repeating properties and according to increasing atomic mass. He used the periodic table to predict the properties of

undiscovered elements.

6.1

Mendeleev’s Periodic Table An Early Version of Mendeleev’s Periodic Table

6.1

The Periodic Law The Periodic Law

◦ How is the modern periodic table organized? In the modern periodic table, elements are arranged

in order of increasing atomic number.

6.1

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 (row)

change as you move across a period from left to right. This same pattern of properties then repeats across the

next period.

6.1

Metals, Nonmetals, and Metalloids Metals, Nonmetals, and Metalloids

◦ What are three broad classes of elements? Three classes of elements are metals, nonmetals,

and metalloids.

6.1

Metals, Nonmetals, and Metalloids

Metals, Metalloids, and Nonmetals in the Periodic Table

6.1

Metals, Nonmetals, and Metalloids

Metals, Metalloids, and Nonmetals in the Periodic Table

6.1

Metals, Nonmetals, and Metalloids

◦ Metals Metals are good conductors of heat and electric

current. 80% of elements are metals. All metals are solids at room temperature except

mercury, which is a liquid. Metals have a high luster, are ductile, and are malleable.

6.1

Metals, Nonmetals, and Metalloids

Uses of Iron, Copper, and Aluminum

6.1

Metals, Nonmetals, and Metalloids

Uses of Iron, Copper, and Aluminum

6.1

Metals, Nonmetals, and Metalloids

Uses of Iron, Copper, and Aluminum

6.1

Metals, Nonmetals, and Metalloids

Metals, Metalloids, and Nonmetals in the Periodic Table

6.1

Metals, Nonmetals, and Metalloids

◦ 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.

6.1

Metals, Nonmetals, and Metalloids

Metals, Nonmetals, and Metalloids

Metals, Metalloids, and Nonmetals in the Periodic Table

6.1

Metals, Nonmetals, and Metalloids

◦ 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. Metalloids are also known as semi-metals.

6.1

Metals, Nonmetals, and Metalloids

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.

6.1

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

◦ Down a group (column), the properties of elements become more metallic and less nonmetallic.

Where is the most metallic element?

Metallic Character

6.2

Classifying the Elements

A coin may contain much information in a small space—its value, the year it was minted, and its country of origin. Each square in a periodic table also contains information. You will learn what types of information are usually listed in a periodic table.

6.2

Squares in the Periodic Table Squares in the Periodic Table

◦ What type of information can be displayed in a periodic table? The periodic table displays the symbols and names

of the elements, along with information about the structure of their atoms.

http://www.privatehand.com/flash/elements.html

The Element Song!

Squares in the Periodic Table Some element families have names:

◦ The Group 1 elements are called alkali metals.◦ The Group 2 elements are called alkaline earth

metals.◦ The nonmetals of Group 17 are called halogens.◦ The nonmetal gases of group 18 are called noble

gases.

6.2

6.2

Electron Configurations in Groups Electron Configurations in Groups

◦ How can elements be classified based on their electron configurations? Elements can be sorted into groups based on their

electron configurations. Elements in the same family have the same outer

electron configuration = valence electrons.

6.2

Electron Configurations in Groups

◦ The Noble Gases The noble gases are the elements in Group 18 of

the periodic table; all noble gases have a full outer electron energy level.

6.2

Helium (He) 2Neon (Ne) 2-8Argon (Ar) 2-8-8Krypton (Kr) 2-8-18-8

Electron Configurations in Groups

◦ The alkali metals. In atoms of the Group 1 elements below, there is

only one electron in the highest occupied energy level; one valence electron.

6.2

Lithium (Li) 2-1Sodium (Na) 2-8-1Potassium (K) 2-8-8-1

Electron Configurations in Groups

◦ The carbon family In atoms of the Group 14 elements below, there are

four valence electrons.

6.2

Carbon (C) 2-4Silicon (Si) 2-8-4Germanium (Ge) 2-8-18-4

Transition Elements Transition Elements

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

6.2

Transition Elements In atoms of a transition metal, the d sublevel is

filling with electrons. In atoms of an inner transition metal, the f sublevel

is filling with electrons.

6.2

Transition Elements◦ Blocks of Elements

6.2

The Elements: Forged in Stars - YouTube

The Elements: Forged in Stars

In the Earth’s Crust:◦ Oxygen◦ Silicon◦ Aluminum◦ Iron◦ Calcium◦ Sodium◦ Potassium◦ Magnesium◦ Titanium◦ Hydrogen

Elements Around You

Dissolved in the Oceans:◦ Chlorine◦ Sodium◦ Magnesium◦ Sulfur◦ Calcium◦ Potassium◦ Bromine◦ Carbon◦ Strontium◦ Boron

Elements Around You

In the Atmosphere:◦ Nitrogen◦ Oxygen◦ Argon◦ Neon◦ Helium◦ Krypton◦ Hydrogen◦ Xenon◦ Radon

Elements Around You

In the Sun:◦ Hydrogen◦ Helium◦ Oxygen◦ Carbon◦ Nitrogen◦ Silicon◦ Magnesium◦ Neon◦ Iron◦ Sulfur

Elements Around You

In your body:◦ Oxygen◦ Carbon◦ Hydrogen◦ Nitrogen◦ Calcium◦ Phosphorus◦ Sulfur◦ Potassium◦ Sodium◦ Chlorine

Elements Within You

Soft, silver-grey metals. Low melting and boiling points. One valence electron. Most reactive: not found uncombined in

nature.◦ Obtained in the pure form by electrolysis of their

fused salts. Potassium Video - The Periodic Table of Vide

os - University of Nottingham

Group 1: Alkali Metals

Relatively soft, but harder than alkali metals. Two valence electrons. Although not as reactive as alkali metals, still

very reactive and not found in nature in the elemental state.◦ Obtained in the pure form through electrolysis of

their fused salts. Densities, melting and boiling points are

higher than respective alkali metals. Radium Video - The Periodic Table of Videos -

University of Nottingham

Group 2: Alkaline Earth Metals

Most are ductile, malleable and good conductors of heat and electricity.

Compounds of transition metals tend to have color.

One or two valence electrons. Obtained from mineral deposits (ores) in the

earth’s crust (smelting). Precious metals are used for currency among

other things. Darmstadtium

Video - The Periodic Table of Videos - University of Nottingham

Transition Metals

Nonmetals. Very reactive; not found in nature

uncombined.◦ Obtained from the electrolysis of their fused salts.

Seven valence electrons. Commercial applications include

antibacterial properties. Chlorine Video - The Periodic Table of Videos

- University of Nottingham

Group 17: Halogens

Full outer electron level. Non-reactive (inert) gases.

◦ Can be forced to combine with fluorine. Commercial applications include colored

signs lit up as discharge tubes. Incandescent light bulbs are filled with

argon. Radon Video - The Periodic Table of Videos -

University of Nottingham

Group 18: Noble Gases

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.

6.3

Trends in Atomic Size Trends in Atomic Size

◦ What are the trends among the elements for atomic size? The atomic radius is one half of the distance

between the nuclei of two atoms of the same element when the atoms are joined.

6.3

Trends in Atomic Size◦ 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. Down a group, atomic size increases due to additional

energy levels. Across a period atomic size decreases due to increasing

nuclear charge.

6.3

Trends in Atomic Size

6.3

Trends in Atomic Size

6.3

Ions 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.

6.3

Ions Ions

◦ How do ions form?

6.3

Ions

Positive ions form when an atom loses electron(s).

6.3

IonsNegative ions form when an atom gains electron(s).

6.3

Trends in Ionization Energy Trends in Ionization Energy

◦ What are the trends among the elements for first ionization energy, ionic size, and electronegativity? 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 a second electron is

called the second ionization energy.

6.3

Trends in Ionization Energy◦ Group and Periodic Trends in Ionization Energy

First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period. Down a group increasing levels of electrons shield the

effect of the nucleus therefore reducing energy needed to remove an outer electron.

Across a period there in no increase in energy levels, and increasing nuclear charge makes it more difficult to remove an outer electron.

6.3

Trends in Ionization Energy

6.3

Trends in Ionization Energy

6.3

Trends in Ionic Size Trends in Ionic Size

◦ 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. Cations are always smaller than the atoms from

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

they form.

6.3

Trends in Ionic Size Relative Sizes of Some Atoms and Ions

6.3

Trends in Electronegativity◦ Electronegativity is the ability of an atom to

attract electrons to itself when it is in involved in a bond. In general, electronegativity values decrease from

top to bottom within a group, and increase from left to right across a period. Electronegativity decreases down a group because of

increasing atomic size and the shielding effect of inner level electrons.

Electronegativity increases across a period because of decreasing atomic size and increasing nuclear charge.

6.3

Trends in Electronegativity

Summary of Trends Summary of Trends

◦ What is the underlying cause of periodic trends? Periodic trends can be explained by variations in

atomic structure, nuclear charge, and shielding effect.

6.3