On the sixth of March, 1869, Dmitri Ivanovich Mendeleyev presented the periodic table of elements to the world. The table demonstrated that the elements, which are the building blocks of the universe, could be placed in order of their atomic weights, whereupon they would fall into groups having only a few discrepancies between characteristics.
What Is the Periodic Table of Elements?
The periodic table of elements is a graphical representation of the periodic law. The periodic law dictates that elements sharing similar properties show up in groups, based upon their atomic weight (as originally proposed by Mendeleyev) or, more accurately, atomic number. Mendeleyev felt confident enough in this law to assert in his presentation that the several missing elements needed to make his table work did exist, but hadn’t been discovered. Accordingly, he assigned their places and properties. To make his periodic law work out, Mendeleyev challenged several of the atomic weights, using his law to prove that they had been measured wrong. He was right in several cases. It was discovered that the table was more periodic, shall we say, if the elements were arranged by atomic number, not atomic weight as Mendeleyev proposed. In today’s periodic table of elements, the order of the substances are based upon atomic number.
The Atomic Number
The use of the atomic number was proposed in 1911 by Dutch physicist Antonius van den Broek. The number itself represents the proton count in the element. Generally speaking, the higher the weight, the higher the atomic number. It is to be noted, however, that there are a few exceptions where the atomic weight does not correspond so nicely with the atomic number. For example, cobalt has an atomic number of 27 and an atomic weight of 58.9332, while nickel, the following element with an atomic number of 28, has an atomic weight of 58.7.
The Electron Count
The significance of the periodic law is that elements can be classified into groups with similar properties, such as metals, metalloids, and nonmetals. These groups can be even further divided into other groups, based upon various properties and characteristics. This is possible because the electron count of the atom defines its characteristics, and the electron count always equals the proton count. Hence:
- The properties of an element can be judged merely from where it lies on the table.
- Where an element lies on the table is determined solely upon its atomic number.
- The atomic number represents how many protons are in an element.
- For an uncharged element, the atomic number also represents how many electrons are in the given element.
- The electron count is a huge factor in determining an element’s properties.
- Thus the periodic table is a powerful tool!
Helpful, If Not Perfect
Still, a few elements simply refuse to be reconciled with the periodic law. As with all classification systems, there are outliers. An example is radon, which is classed as a nonmetal and more specifically as a noble gas, but has some characteristics which are closer to a metal. Despite its limitations, the periodic table of elements remains highly useful — not just as an organizing system, but as a means to study the elements.
Dmitry Ivanovich Mendeleyev
Professional biography from Michigan Tech.
Developing the Periodic Table
A two-and-a-half-minute video explaining the history of the periodic table from NOVA.
Interactives: The Periodic Table
History and explanation from Annenberg Learner.
Periodic Table and the Elements
Explains the periodic table, and looks at the 18 elements that make up most of the matter in the universe. Click on “Next Stop on Site Tour” to continue through the tutorial.
Dynamic Periodic Table
Incredible website that allows you to learn about each element, its properties, how it is used, where you will find it, and different compounds that use it — all with a click!
Excellent video series for each element in the chart from the University of Nottingham.
Element of the Day
Sheets for recording the particulars about each element — one a day. Great idea! Use the two resources above to learn about each element.
Several different types of games to learn about the periodic table elements from Sheppard Software.
Periodic Table Scavenger Hunt
Worksheet that helps build familiarity with the table.
Print back-to-back to make element cards. Great for making a hands-on periodic table!
Fast-paced card game where student use clues to become more familiar with the elements.
Printable Periodic Table
Editable spreadsheet format that can be modified; for example, delete element symbols, etc. for practice.
Periodic Table Unit Test
A Quia quiz with 50 questions for wrapping up.
Periodic Table of the Elements Placemat
We used these when our children were young (gems and minerals, U.S. Presidents, map of the United States, animal tracks, etc.). Not exactly a book, but a great way to become familiar with the Periodic Table!
Unit Studies & Lesson Plans
Periodic Table Curriculum
Wonderful resource from Ag in the Classroom for older students that offers great explanations of how the table (and chemistry) works while the activities are geared toward agricultural applications.
Study Guide for Atoms and Periodic Table Unit Test
No, there won’t really be a test, but if your student knows everything on this chart from the Cobb County School District, he is VERY familiar with the periodic table!
The Periodic Table
Excellent lesson plan that not only does a great job explaining the periodic table and has helpful activity sheets, but is also interesting for students!
Printables & Notebooking Pages
Hunting the Elements
Beautiful periodic table poster from PBS/NOVA.
The Periodic Table of the Elements, in Pictures
Great for notebook!
Periodic Table of the Elements
Another illustrated table from the Foundation for Education, Science and Technology.
Notebooking page at HSPrintables.com that can be used as another option for recording the element of the day, as mentioned above (scroll down).
The Periodic Table of Elements Notebooking Pages
Simple pages for copywork, narrations, or wrapping up.