Chemistry

How the Periodic Table of Elements used in Chemistry



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When a layperson looks at the elaborate Periodic Table of the Elements, he or she may think it looks like a game of Spider Solitaire; It's clear that the chart has nothing to do with cards or insects!  To hopeful chemistry students, it is a roadmap to the elements and to established chemists, it is the key in understanding chemical properties and reactions of the atoms; however, in order to use the table, a person would have to have working knowledge of how it’s organized and notated. 

Nomenclature

Each element is represented by a square on the Periodic Table of Elements and each is denoted by it’s own unique series of letters.  Hydrogen is H and Helium is He.  An element can have one to three letters in its chemical name. 

The elements are listed in increasing atomic number order.  And in each element square, an atomic number and atomic mass are included. The atomic number represents the number of protons in the nucleus or the electrons orbiting the nucleus. The atomic mass is the average mass of the protons, electrons and neutrons in a single atom.

Parts of the Table

Groups

Groups are noted by the vertical column and represent families of elements. These groups, which there are 18, consists of the elements have similar chemical and physical properties.  For example, Group 18 consists of the noble gases - Helium, Neon, Argon, Radon, Ununoctium, Krypton and Xenon.  These elements have low melting and boiling points, and they each are colorless, odorless, tasteless, and nonflammable. This group is known for its low chemical reactivity.   

Periods

Periods are noted by the horizontal rows on the periodic chart.   Each element in a period row tends to have the same number of electron orbits.   Based on what man knows about the existing elements, seven is the maximum number of orbits and element can have. 

The periodic chart has 7 periods.   Elements such as Hydrogen and Helium are in Period 1- meaning they have one electron orbit.  Elements such as Sodium and Magnesium, Aluminum, Potassium and Chlorine are in Period 3- meaning they have there electron orbits.

Other Useful Aspects

Blocks

While groups and periods are useful in understanding the chemical families, elements are also seen as being organized by blocks.  There are 4 blocks (s, d, p and f) and blocks represent the subshell in which the last electron of the element resides.  This pairing relates to atomic orbit type.  The s block family includes hydrogen, helium, the alkali metals and the alkaline earth metals.  Basically, the s block has Groups 1 and 2.  The d block family consists of groups 3 to 12 while the p block holds have groups 13 through 18.  The f block holds the rare earth metals which include the Lanthanoids. Over time, a g block may be added to represent the adding of an 8th and 9th period.

Colors

Over time a color scheme has been added to the periodic chart to help discern which elements belong to named categories.   Charts vary, but most link elements in these categories Alkali metals, Alkaline earth metals, Inner Transitional, Lantanoids and Actinoids, Transitional, Metals, Metalloids, Halogens Other nonmetals, and Noble Gases.

How to Use the Table

Knowing the lay out of the periodic table helps.  Reading the table from left to right or from top to bottom, a viewer will see the groupings and relationships of the elements.

In reviewing the information on each element, you will see that the symbol, atomic number and atomic mass.  The symbol will be used to denote the element in chemical equations.  The atomic number will let you know the number or protons (or electrons) in the element. And, the atomic mass will give you a clue as to the average mass of the element.  This mass takes into account isotopes of the elements.

Using the electron subshell groupings and the periods, a student or chemist can predict an elements stability, boiling point and level of conductivity.   They can predict properties such as stability, boiling point, and conductivity

118 elements strong, the Periodic Table of the Elements is a useful tool in evaluating the nature of elements and predicting chemical reactions. It is one of the most useful tools in chemistry and physics.  The history of the chart and its use will continue to evolve as more elements are discovered and subatomic properties are explored.

For more information on the Periodic Table of Elements, you can go to your local library, chemistry teacher, or book store.  Also, the Internet has several useful resources, which include:

http://periodic.lanl.gov/use.html

http://periodic.lanl.gov/default.htm

http://chemistry.about.com/library/blperiodictable.htm

http://www.wou.edu/las/physci/ch412/perhist.htm

http://www.colorado.edu/physics/2000/periodic_table/index.html

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ARTICLE SOURCES AND CITATIONS
  • InfoBoxCallToAction ActionArrowhttp://periodic.lanl.gov/use.html
  • InfoBoxCallToAction ActionArrowhttp://periodic.lanl.gov/default.htm
  • InfoBoxCallToAction ActionArrowhttp://chemistry.about.com/library/blperiodictable.htm
  • InfoBoxCallToAction ActionArrowhttp://www.wou.edu/las/physci/ch412/perhist.htm
  • InfoBoxCallToAction ActionArrowhttp://www.colorado.edu/physics/2000/periodic_table/index.html