The Periodic Table Introduction and Overview

The Father of the Periodic Table— Dmitri Mendeleev Mendeleev ( ) was the first scientist to notice a relationship between the elements Mendeleev ( ) was the first scientist to notice a relationship between the elements Around 1865 he arranged his periodic table by atomic mass Around 1865 he arranged his periodic table by atomic mass Said properties of unknown elements could be predicted by the properties of elements around the missing element Said properties of unknown elements could be predicted by the properties of elements around the missing element

Dmitri Mendeleev

The Periodic Table Henry Moseley ( ) later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass. Henry Moseley ( ) later discovered that the periodic nature of the elements was associated with atomic number, not atomic mass.

Here is a “periodic” table. What is it?

The columns are called “GROUPS” or families. What is represented by the groups on this periodic table? DAYS

The rows are “PERIODS”. What information is in the horizontal periods? WEEKS

The Periodic Table Column = Group or Family 18 columns on the Periodic Table Row = Period 7 rows on the Periodic Table

Groups Each column is called a “group” or family. Each element in a group has the same number of electrons in its outer orbital, also known as its outer shell. Except for He, it has 2 electrons The electrons in the outer shell are called “valence electrons.” Hint: Your Family tree is vertical.

Periods Each row is called a “period” The elements in each period have the same number of electron shells Hint: A period comes at the end of a sentence--a horizontal line.

What does the information in the box tell me? 1H1.008 Atomic Number = # of protons and # of electrons Atomic Mass = # of protons plus neutrons Elemental Symbol

Metals, Nonmetals, and Metalloids Metals are to the left of the stair- step Hydrogen (H) the only nonmetal on the metal side Nonmetals are on the right of the stair-step Semi-metals, “metalloids,” touch the stair-step

VALANCE ELECTRONS The electrons that are in the outermost energy level of any atom. Examples: Hydrogen has 1 valance electron Oxygen has 6 valance electrons Argon has 8 valance electrons Boron has 3 valance electrons

Most atoms are more stable if they Most atoms are more stable if they have 8 valence electrons. IMPORTANT!! IMPORTANT!! Number of Valence Electrons determines many properties like …How they bond to other atoms Number of Valence Electrons determines many properties like …How they bond to other atoms

The Groups of the Periodic Table Group 1 or 1a: The Alkali Metals Group 1 or 1a: The Alkali Metals HIGHLY REACTIVE metals HIGHLY REACTIVE metals Rarely found free in nature Rarely found free in nature Charge of +1, 1 valence electron Charge of +1, 1 valence electron

Group 2 or 2a: The Alkaline Earth Metals Group 2 or 2a: The Alkaline Earth Metals Still quite reactive: loses 2 electrons easily Still quite reactive: loses 2 electrons easily Charge of +2, 2 valence electrons Charge of +2, 2 valence electrons

T he Groups of the Periodic Table Groups 3-12 or Transition Metals Groups 3-12 or Transition Metals Good Conductors Good Conductors Found freely and in compounds in nature Found freely and in compounds in nature Charge is usually +2 but can vary—usually 2 valence electrons Charge is usually +2 but can vary—usually 2 valence electrons Not very reactive Not very reactive

Transition Metals Transition Metals have slightly different rules for shells and valence electrons. This is something you will learn about in High School Chemistry. For now, assume they each have two valence electrons.

Group 13 or 3a: Boron Family Group 13 or 3a: Boron Family Charge is +3, 3 valence electrons Charge is +3, 3 valence electrons

The Groups of the Periodic Table Group 14 or 4a: The Carbon Family Group 14 or 4a: The Carbon Family Contains elements that can form unusual bonds (carbon and silicon) Contains elements that can form unusual bonds (carbon and silicon) Charge is +4 or -4, contains 4 valence electrons Charge is +4 or -4, contains 4 valence electrons

Group 15 or 5a: The Nitrogen Family Group 15 or 5a: The Nitrogen Family Charge is -3, contains 5 valence electrons Charge is -3, contains 5 valence electrons

The Groups of the Periodic Table Group 16 or 6a: The Oxygen Family Group 16 or 6a: The Oxygen Family Also known as the chalcogens Also known as the chalcogens Charge is -2, 6 valence electrons Charge is -2, 6 valence electrons

Group 17 or 7a: The Halogens Group 17 or 7a: The Halogens Most reactive nonmetals Most reactive nonmetals charge is -1, 7 valence electrons charge is -1, 7 valence electrons

Group 18 or 8a: The Noble Gases (The Inert Gases) Group 18 or 8a: The Noble Gases (The Inert Gases) Inert means Nonreactive, don’t normally react with other elements Inert means Nonreactive, don’t normally react with other elements Charge is 0, 2 or 8 valence electrons Charge is 0, 2 or 8 valence electrons

Metal vs. Nonmetal Metal vs. Nonmetal -Physical Properties: *Solid at room temp *Solid at room temp *Shiny *Shiny *Malleable *Malleable *Ductile *Ductile *Good conductors of *Good conductors of heat & electricity heat & electricity -Chemical Properties: *Reactivity varies *Reactivity varies *usually LOSES electrons *usually LOSES electrons -Physical Properties: -Physical Properties: *Usually gas at room temp *Usually gas at room temp *Dull *Dull *Brittle *Brittle *lower density *Poor conductors of heat & electricity heat & electricity -Chemical Properties: *VERY Reactive *VERY Reactive *by GAINING electrons *by GAINING electrons *Fl-most reactive element

Chemical Properties of Metals 1. Reactivity- 1. Reactivity- Ease and speed that an element combines or reacts with other elements Ease and speed that an element combines or reacts with other elements Determined by the elements tendency to give up an electron Determined by the elements tendency to give up an electron Na reacts strongly if exposed to air or water…to prevent a reaction sodium is stored under oil in a sealed container Na reacts strongly if exposed to air or water…to prevent a reaction sodium is stored under oil in a sealed container Gold and Platinum are valued for their lack of reactivity and rareness. Gold and Platinum are valued for their lack of reactivity and rareness.

Examples of Reactivity Corrosion – Corrosion – destruction of metal destruction of metal Ex. - Fe (Iron) reacts slowly with Oxygen in the air, forming iron oxide, or Rust. Ex. - Fe (Iron) reacts slowly with Oxygen in the air, forming iron oxide, or Rust.

Special Rows on the PT Lanthanides Actinides We call these rare earth metals because they are rarely found on earth.

What are the rare earth metals? They rarely occur naturally on earth, lathanides more so than actinides. They rarely occur naturally on earth, lathanides more so than actinides. They are placed at the bottom of the period table for convenience – so the table is of a usable size for chemists. They are placed at the bottom of the period table for convenience – so the table is of a usable size for chemists. Elements with atomic numbers higher than 92 are described as synthetic as they are synthesized in particle accelerators. Elements with atomic numbers higher than 92 are described as synthetic as they are synthesized in particle accelerators.

A little more about rare earth metals! Many of these are used in nuclear reactors to produce energy. Many of these are used in nuclear reactors to produce energy. Most of the Actinides are radioactive. Most of the Actinides are radioactive. Again, the reason they are located at the bottom of the table is for convenience only. Again, the reason they are located at the bottom of the table is for convenience only.