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Explanation of the Periodic Table of the Elements - Succeed in Chemistry. Also refer to physical science, compounds, isotopes, molecules, atoms, protons, electrons, neutrons, nucleus, orbits, shells, ions, noble gas, Ron Kurtus, School for Champions. Copyright © Restrictions

Periodic Table of the Elements

by Ron Kurtus (16 April 2007)

The periodic table is an arrangement of the chemical elements that is a powerful tool for studying those elements and how they combine. The elements are arranged in rows according to their atomic number and in columns according to their valence electrons or number of electrons in the outer shell. Elements in a given column have similar chemical characteristics. A detailed periodic table typically gives information on the name, symbol, atomic number, atomic weight, shell configuration and other material.

Questions you may have include:

• How are the elements arranged?
• What do the rows and columns indicate?
• How do you use the table?

This lesson will answer those questions. There is a mini-quiz near the end of the lesson.

Arrangement of elements

The elements in the periodic table are arranged in rows according to atomic number and in columns according to the configuration of the outer orbit or shell.

Partial periodic table

The chart below just shows the first 18 elements, so you can get an idea of how the periodic table arranges them. Since there are over 100 elements, the table is more complex than this.

The elements are listed by their abbreviations. H = Hydrogen, He = Helium, and so on.

First three rows of Periodic Table

Rows and columns

By examining the rows and columns of the periodic table, you can see how useful it can be.

Rows

If you go along the rows from left to right, the elements are numbered 1 - H, 2 - He, 3 - Li, 4 - Be, 5 - B, and so on. The atomic number is also the number of protons in the element's nucleus.

The first row lists just H and He, since they only have one electron shell or orbit. The second row lists elements that have electrons in two shells. Lithium (Li) has one electron in shell 2, while Neon (Ne) has a full shell of 8 electrons. Elements in the third row not only have two electrons in the first shell and eight in the second shell, but they also have electrons in a third shell. Silicon (Si) has four electrons in its outer orbit or shell.

Columns

If you go down a column, each element has the same number of electrons in its outer orbit or shell. For example, H, Li, and Na each has one electron in the outer shell. On the other hand, O, S, and those elements below each has 6 electrons in the outer shell or 2 short of filling the outer shell with 8 electrons. The number of electrons in the outer shell determines the element's chemical properties.

There is a maximum number of electrons allowed in each shell. Only 2 can be in the first shell, 8 in the second, 18 in the third, 32 in the fourth, and so on.

(See The Atom in the Physical Science section for a detailed explanation of the orbits or shells.)

After the half-way point, the columns indicate how many less than full are in the outer orbit or shell. The maximum electrons in the second orbit is 8. Thus Oxygen (O) has 2 electrons less than the maximum of 8 in its outer orbit.

Interactive periodic table

A complete periodic table of the elements is illustrated below. This version of the table is interactive, allowing you to get more information on the various elements. Information on using it is listed below the table.

(Note: To find the name of the element for a given symbol, see the lesson on Chemical Elements.)

Using the table

When you click on any underlined abbreviation for an element, detailed information is displayed in the lower table.

• Name gives the full name of the element
• Number is the atomic number (also the number of protons in the nucleus)
• Weight is the average atomic weight or mass, including isotopes
• Shells are the electron shells or orbits in order (i.e. 2, 8, 8, 3)
• Orbital is an indication of the orbital occupancy of the electrons (this is complex and not really covered or used in our material)
• Melting is the melting point of the material in degrees Celsius
• Boiling is the boiling point of the material in degrees Celsius

So, you can get quite a bit of information from this table.

State at room temperature

The table also color-coded each element as to whether it is solid, liquid or gas at room temperature.

Man-made elements are usually made in such small quantities and are so short-lived that it is difficult to tell what form they exist in. By their placement in the table, they are probably solids.

Summary

You can use this Periodic Table to obtain considerable information about the elements and their relationship to each other, as well as possible chemical combinations.

Answers to Readers' Questions

You have the potential to be great

Resources

The following resources provide information on this subject:

Websites

Chemical Elements.com - Site with details on Periodic Table

Chemistry Resources

Books

Top-rated books on Chemistry

Miscellaneous

Mini-quiz to check your understanding

1. How many elements are there in a standard periodic table?

2. How many electrons does Sodium have in its outer shell?

3. How many shells does Gold (Au) have?

If you got all three correct, you are on your way to becoming a Champion in Chemistry. If you had problems, you had better look over the material again.

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