# The Periodic Table

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• Published : January 13, 2013

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The Periodic Law…………………………. 1.
What Are Elements?..………………………2.
Groups/Periods……………………………. 3.
Electrons………………………………....... 4.
The Families………………………………. 5.
Metals/Non-Metals/Metalloids……………. 6.
Ionization Energy………………………….. 7.
Electronegativity…………………………... 8.
The Octet Rule……………………………. 10.
Glossary………………………………........11.

The Periodic Law

The modern periodic table, based on atomic number and electron configuration, was created primarily by a Russian chemist, Dmitri Ivanovich Mendeleev.

Mendeleev created the first periodic tablebased on atomic weight. He observed that many elements had similar properties, and that they occur periodically, which basically made the table’s name. His periodic law states that the chemical and physical properties of the elements vary in a periodic way with their atomic weights. The modern one states that the properties vary with atomic number, not weight.

What Are Elements?

An Element is a type of atom that is defined by its atomic number (number of protons or electrons), atomic mass, symbol, and much more but for now lets start with the basics. Here is an example of how to read an element off the table:

The name of this element is Sulfur.

This is the Periodic Table of Elements, you can understand the basics of each element by reading them as you just read the image above.

￼Groups and Periods

Periods

Rows of elements are called periods. The period number of an element signifies the highest unexcited energy level for an electron in that element. The number of elements in a period increases as you move down the periodic table because there are more sublevels per level as the energy level of the atom increases

Groups

Columns of elements help define element groups. Elements within a group share several common properties. Groups are elements have the same outer electron arrangement. The outer electrons are called valence electrons. Because they have the same number of valence electrons, elements in a group share similar chemical properties.

Electrons

Electrons:

Electrons are arranged in energy levels around the nucleus. When electrons gain or lose energy, they jump between energy levels as they are rotating around the nucleus. For example, as electrons gain energy, they might move from the second to the third level. Then, as they lose energy, they might move back to the second level or even to the first energy level. Only a certain number of electrons can be in an energy level at the same time.

Valence Electrons:

The presence of valence electrons can determine the element's chemical properties and whether it may bond with other elements: For a main group element, a valence electron can only be the last number of electrons in the configuration. In a transition metal, a valence electron can also be in an inner shell. Each group of the periodic table has its own valence electron. Example: All of group 1‘s elements (Li, Na, K, Rb, Cs, Fr) all have configurations that end with 1.

Electron Configuration:

Electron configuration was first conceived of under the Bohr model of the atom, and it is still common to display the electron shells. Electronic configurations describe electrons as each moving independently in an orbital, in an average field created by all other orbitals. The number of electrons get larger as they go down a group which also increase the number of shells.

The Families

Elements in Mendeleev's table were arranged in rows called periods. The columns were called groups. Elements of each group had similar properties, One property would be that every element of the same group had the same Valence Electron. The Periodic table can be divided into nine families of elements each having similar properties. The families include:

Alkali metals, Alkaline metals, The Transition, metals, Other metals,...