Topic #12: The Periodic Table of Elements. Valence electrons - outermost electrons of an atom, which are important in determining how the atom reacts.

Topic #12: The Periodic Table of Elements

• Valence electrons - outermost electrons of an atom, which are important in determining how the atom reacts chemically with other atoms.

• Ion-atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.

Cation – positively charged ion

Anion – negatively charged ion

• Oxidation Number-is equal to the charge on the ion

The Modern Periodic Table --- continued

Period ( rows on the periodic table)

The periodic table consists of rows called Periods (There are a total of 7 rows or periods, beginning with hydrogen)

•These rows also designate the energy level where electrons are found (more about this when we talk about electron configuration).

The Modern Periodic TableGroups (sometimes called Families)

• are columns numbered from 1-8, followed by a letter “A” or “B”.

•The groups designated with a letter “A” (1A to 8A) are often referred as the main group or the “REPRESENTATIVE ELEMENTS”.

•The groups designated with a “B” (1B through 8B) are referred to as the “TRANSITION ELEMENTS”.

• A more recent numbering system, which uses the numbers 1 through 18, also appears above each group.

The Modern Periodic Table --- Classifying the Elements

Metals --- elements that are generally shiny when smooth and clean, solid at room temperature, good conductors of heat and electricity.• Most metals are ductile (drawn into wires) and malleable (moldable).

Metals are in green

The Modern Periodic Table --- Classifying the Elements

Nonmetals --- elements that are generally gases or brittle, dull-looking solids. They are poor conductors of electricity.•The only nonmetal that is a liquid at room temperature is Bromine.

Non metals are in orange

The Modern Periodic Table --- Classifying the Elements

Metalloids --- elements with physical and chemical properties of both metals and nonmetals.•Silicon and Germanium are two of the most important metalloids, as they are used extensively in computer chips and solar cells.

Metalloids are in purple

THE REPRESENTATIVE ELEMENTS

Group 1A – The Alkali Metals• Elements in this family have 1

valence electron. • Lose their valence electron to form a

+1 charged ion.• Belong to the s-block in the periodic

table.

THE REPRESENTATIVE ELEMENTSGroup 2A – The Alkaline Earth Metals

• Elements in this family have 2 valence electrons.

• Lose their valence electrons to form a +2 charged ion.

• Belong to the s-block in the periodic table.

THE REPRESENTATIVE ELEMENTS

Group 3A – The Boron Group

• Is named for the metalloid Boron

• Elements in this family have 3 valence electrons

• Lose their valence electrons to form a +3 charged ion.

• Belong to the p-block in the periodic table

THE REPRESENTATIVE ELEMENTS

Group 4A – The Carbon Group

• Is named for the nonmetal Carbon• Elements in this family have 4 valence

electrons • Lose their valence electrons to form a

+4 charged ion OR can gain 4 electrons and form a –4 charged ion.

• Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS

Group 5A – The Nitrogen Group

• Is named for the nonmetal Nitrogen• Elements in this family have 5 valence

electrons • Gain 3 electrons to form a -3 charged ion.

Except Bismuth, which can lose 3 electrons and form ions with a +3 charge.

THE REPRESENTATIVE ELEMENTS

Group 6A – The Oxygen Group

• Is named for the nonmetal Oxygen. • Elements in this family have 6 valence

electrons.• Gain 2 electrons to form a -2 charged ion.• Polonium is the most metallic member of

this family; it was discovered by Marie & Pierre Curie and named after there native land Poland; it is rare, radioactive & extremely toxic.

• Contains all three classifications: oxygen and sulfur are nonmetals, selenium & tellurium are metalloids, and polonium is a metal.

• Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS

Group 7A – The Halogens• Are named for their ability to form compounds

with all metals. Because these compounds are called salts, Group 7A are called “salt formers,” or Halogens

• Elements in this family have 7 valence electrons.

• Gain 1 electron to form a -1 charged ion.• Fluorine is a gas & the most reactive of all

halogens. • Belong to the p-block in the periodic table.

THE REPRESENTATIVE ELEMENTS

Group 8A – The Noble Gases• Were among the last naturally

occurring elements to be discovered because they are colorless and unreactive.

• Elements in this family have 8 valence electrons. This means they have the maximum number of electrons in their outermost energy level, 8, except for helium, which has two.

• Belong to the p-block in the periodic table.

THE TRANSITION METALSGroups 1B- 8B (or more commonly referred to as Groups 3-12)

• Most are hard solids with high melting & boiling points.

• Transition metals can lose 2 s electrons and form an ion with a +2 charge

• Because unpaired electrons can move to the outer energy level, these elements can form ions with a +3 charge or higher, as well.

• Transition metals belong to the d-block in the periodic table

THE INNER TRANSITION METALS -- The Lanthanide Series(Period 6 on the Periodic Table)

• Silvery metals with relatively high melting points.

• Because there is very little variation in properties among the inner transition metals, they are found mixed together in nature and are extremely difficult to separate.

• Belong to the f-block in the periodic table

THE INNER TRANSITION METALS -- The Actinide Series (Period 7 on the Periodic Table)

• Actinides are radioactive elements.

• Belong to the f-block in the periodic table

• The atomic radius of a chemical element is a measure of the size of its atoms.

• Electronegativity, is a chemical property that describes the ability of an atom to attract electrons towards itself.

• The Electron affinity of a molecule or atom is the energy change when an electron is added to the neutral species to form a negative ion.

• The ionization energy (EI) of an atom is the minimal energy required to remove electrons from atoms.

Electronegativity

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