By: Cathy Yang

The Periodic Table

History of the Periodic Table Chemists had been searching or a

precise classification scheme of the known elements at that time.

The history of the periodic table reflects over a century of growth in the understanding of chemical properties. The most important event in its history occurred in 1869, when the table was published by Dmitri Ivanovich Mendeleev, who built upon earlier discoveries by scientists such as Antoine-Laurent de Lavoisier and John Newlands.

The modern Periodic Table is largely based upon Mendeleev’s model.

The Periodic Table is an arrangement of elements based on their atomic number, electron configurations, and recurring chemical similarities.

Elements are presented in order of increasing atomic number.

The Periodic Table

Squares of the Periodic TableDifferent tables give different

information, but they will usually include: The atomic number, referring

to how many protons an atom of the element has. Oxygen’s atomic number is 8, so it has 8 protons.

The chemical symbol of the element and its name. For example, the chemical symbol of Oxygen is O.

The atomic mass, the “weight” of the atom calculated by adding the number of protons with the number of neutrons.

The standard periodic table has 18 columns and 7 rows with two rows of elements below that.

Layout of the table

Groups/families PeriodsGroups, or families are

organized in columns with elements with similar chemical properties going in a vertical line numbered 1 to 18.

Four significant groupsGroup 1: the Alkali metalsGroup 2: the Alkaline

Earth MetalsGroup 17: the HalogensGroup 18: the Noble gases

Periods are organized in rows with increasing atomic numbers going left to right and top to bottom, and are numbered 1 to 7.

The elements in a period do not share similar chemical properties.

The first element in a period is always an extremely active solid and the last element in a period is always an inactive gas.

The Periodic Table can also be organized by categories. The elements can be conveniently classified according to their shared physical and chemical properties into the major categories of metals, metalloids, and non-metals.

Organizing by Categories

Non-metal – Hydrogen Hydrogen is located

above the Alkali family, but is not a member of it. Hydrogen can be classified as its own family.

It is in gas form at room temperature.

It has one proton, one electron, and only one energy level.

Hydrogen requires two electrons to fill its valence shell.

Hydrogen is the most abundant element in the Universe, making up ¾ of all matter.

Metals – Alkali MetalsFound in the first column

of the Periodic Table.The atoms of Alkali metals

have one valence electron.They’re shiny, extremely

reactive, and are malleable.

They react violently with water.

They’re never found independently in nature since they’re combined with another element.

They’re never found uncombined with another element in nature.

They have two valence electrons.They’re reactive, but not as reactive as the

Alkali metals.

Metals – Alkaline Earth Metals

Metals – Transition metalsContains the metals that

are the most familiar to people, such as: copper, tin, zinc, iron, nickel, gold, and silver.

They’re good conductors of heat and electricity.

Their compounds are usually brightly colored and often used to color paints.

Transition elements usually have 1 or 2 valence electrons.

Transition elements have similar chemical properties with other metals, but their properties do not fit in with any other family.

Many transition metals chemically combine with oxygen to form oxides.

Metals – Transition metals (cont.)

Non-metal – HalogensHalogens have seven

valence electrons, making them the most active non-metals.

They’re never found by themselves in nature.

Atoms only need to gain one electron to completely fill their valence shells.

They react with Alkali metals to form salts.

Non-metal – Noble GasesNoble Gases are colorless

gases that are completely unreactive.

They’re inactive because their outermost valence shell is full, already having eight valence electrons.

They do not easily combine with other elements to form compounds, so the Noble Gases are called inert.

Noble Gases are found in small amounts in the Earth’s atmosphere.

Noble Gases

Metals - Rare Earth ElementsThe seventeen Rare Earth

Elements are composed of the Lanthanide series plus Scandium and Yttrium.

Despite their name as Rare Earth Elements, they are relatively abundant in the Earth’s crust.

One element from the Lanthanide series and most elements from the Actinide series are called trans-uranium, which means synthetic or man-made.

Boron familyNamed after the first

element in the family, Boron.

Elements have three valence electrons.

Includes a metalloid, Boron, but the rest are metals.

Includes the most abundant metal in the Earth’s crust, Aluminum.

Carbon FamilyAtoms have four

valence electrons.Includes a non-metal,

Carbon, metalloids, and metals.

Carbon element is called the “basis of life.”

Organic chemistry is a branch of chemistry devoted to Carbon compounds.

Nitrogen FamilyNamed after the

element that makes up about 78% of the atmosphere, Nitrogen.

Includes non-metals, metalloids, and metals.

Atoms have five valence electrons and tend to share electrons when they bond.

Oxygen familyNamed after Oxygen.

Oxygen is the most abundant element in the Earth’s crust, making up about 46.6% of the Earth’s mass.

It is extremely active and combines with almost all the elements.

Atoms have six valence electrons.

Most elements share electrons when forming compounds.

Organizing by Blocks The table can also be

deconstructed into four rectangular blocks.

Named according to the subshell in which the “last” electron resides. s-block consists of the Alkali

metals and the Alkaline metals as well as hydrogen and helium.

p-block consists of groups 13 to 18, contains all of the metalloids.

d-block consists of 3 to 12, contains all of the transition metals.

f-block, which is usually the two rows below the rest of the table, consists of the Lanthanides and Actinides.

The Periodic Table can be used to find: The number of protons Number of neutrons Number of electrons The valence electrons The electron configuration The number of shells The atomic number Mass number Atomic mass number Whether the element is a metal, non-metal, or metalloid Whether the element is a solid, liquid, or gas How reactive the element is The physical and chemical properties of the element The chemical bonding possibilities of the element, etc

Use of the Periodic Table

http://www.wou.edu/las/physci/ch412/perhist.htmhttp://www.can-do.com/uci/lessons98/Periodic.htmlhttps://www.youtube.com/watch?v=0RRVV4Diomghttp://en.wikipedia.org/wiki/Chemical_elementhttp://www.chem4kids.com/files/elem_families.htmlhttp://www.learner.org/interactives/periodic/groups.

htmlhttp://chemistry.about.com/cs/howthingswork/f/blab

undant.htmhttp://www.powayusd.com/teachers/mnelson/PowerP

oints%20for%20Posting/periodic%20table.ppt_files/frame.htm

http://en.wikipedia.org/wiki/Rare_earth_elementhttp://www.chemicalelements.com/groups/rareearth.

htmlhttp://en.wikipedia.org/wiki/Rare_earth_element

Sources