Ch. 6: The Periodic Table

6.1 Organizing the ElementsMendeleev, Periodic Law, metals, nonmetals, metalloids

6.2 Classifying the Elementssquares in the periodic table, periods and groups (p. 118), electron configurations, transition elements

6.3 Periodic Trendsatomic size, ions, ionization energy, ionic size,

electronegativity

The properties of the elements exhibit trends and these trends can be predicted with the help of the periodic table. They can also be explained and understood by analyzing the electron configurations of the elements. This is because, elements tend to gain or lose valence electrons to achieve the stable octet formation. (http://perfectprintables.myfuntips.com/documents/printableperiodictable.html)

6.1 Organizing the ElementsChemists used the properties of elements to sort them into

groups Chlorine, bromine, and iodine have very similar

chemical properties. (Dobereiner, 1829)

6.1

Mendeleev is given credit for an organized table; he arranged the elements in his periodic table in order of increasing atomic mass.

However, there were many other versions before we accepted Mendeleev’s version. Today, we arrange by atomic number instead of atomic mass.

Alchemy & Diderot's Alchemical Chart of Affinities (1778)

Lavoisier's Table of Simple Substances (1789)

John Dalton Elements

A very early notebook (1803)

A fuller list of Dalton's elements and symbols (1808)

Johann Dobereiner's Triads (1780 - 1849)

The Telluric Helix or Screw (1862)

Newlands' Octaves (1864)

Meyer's Periodic Table of 1870

Mendeleev's Tables of 1869 and 1871

More examples!

An Early Version of Mendeleev’s Periodic Table

6.1

He published his work early.

Newly discovered elements fit into his model.

The Periodic LawThe 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.

6.1

periods are the rows 1-7groups or families are the columns (use IA to VIIIA for representative elements and noble gases

Metals, Nonmetals, and Metalloids

»Metals, Metalloids, and Nonmetals in the Periodic Table

6.1

Metals, Nonmetals, and Metalloids

6.1

Metals are good conductors of heat and electric current.–80% of elements are metals.

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

Metals, Nonmetals, and Metalloids

» Uses of Iron, Copper, and Aluminum

6.1

Metals, Nonmetals, and Metalloids6.1

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.

Metals, Nonmetals, and Metalloids6.1

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.

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

6.2 Classifying the Elements

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

6.2

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.The nonmetals of Group 7A are called halogens.

6.2

Electron Configurations in GroupsElements 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.

6.2

Group 1A elements -- there is only one electron in the highest occupied energy level.

Group 4A elements -- there are four electrons in the highest occupied energy level.

Electron Configurations in GroupsElements can be sorted into noble gases, representative elements, transition metals, or inner transition metals based on their electron configurations.

6.2

noble gases are the elements in Group 8A

Representative Elements6.2

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

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

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

6.2

6.3 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

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.

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

6.3

Trends in Atomic Size6.3

Size generally decreases

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

Ions

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

6.3

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.

Chlorine gained an electron and becomes an anion; sodium loses an electron and becomes a cation

Trends in Ionic SizeDuring 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

Relative Sizes of Some Atoms and Ions

Trends in Ionic Size

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Trends in Ionization EnergyThe 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.

6.3

Energy generally increases

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.

Trends in ElectronegativityElectronegativity 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.

6.3

What you need to know: Ch. 6

• What is the underlying cause of periodic trends?

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

• Ch. 6 packet (worksheets, periodic table activity, elements videos)

• Vocabulary: group or family, period; metals, nonmetals, metalloids; alkali metals, alkaline earth metals, halogens; noble gases, representative elements, transition metals, inner transition metals; atomic radius, cation, anion, ionization energy, electronegativity

For example…can you talk about period, group, family, energy levels, valence electrons, electron configuration, cations, anions, metals, non-metals, metalloids, transition elements, alkali metals, alkaline earth metals, halogens, noble gases, lanthanides, actinides, representative elements, Mendeleev, trends (atomic radius, ionization energy, valence electrons, electronegativity)?