Representative Elements of the Periodic Table: Definition & Overview

Lesson Transcript
Instructor: Julie Zundel

Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.

You might not think salt and a banana have much in common, but they do! The periodic table organizes elements into groups based on similar properties. This video will explore the representative elements, focusing on each group or family.

Definition of Representative Elements

It's 3 a.m., and you can't sleep. Your mind is racing from all of the element talk from the previous day:

  • Make sure you get enough calcium so your bones can grow.
  • You have a leg cramp? Eat a banana so you can get potassium.
  • Don't forget to get those helium balloons for your brother's party.
  • Take the aluminum cans to the recycle center.
  • Stop by the vet and get some iodine for Fluffy's cut.

So many elements! If only there was a way to organize them so you can get some sleep. But wait, there is! Take a look at this, it's the periodic table of elements, and it's the solution to all of your problems. Okay, maybe not, but it is quite impressive. The periodic table is a chart that groups elements together based on similar characteristics and atomic structures.

The Periodic Table
The Periodic Table

You'll notice that the symbols are used to save room. For example, instead of aluminum, the periodic table says Al. We will be focusing on their representative elements, which are sometimes referred to as the main group elements. We'll take a tour of the periodic table and these elements shortly, but we need to go over some vocabulary first.

When you look at the table, it's helpful to be familiar with some vocabulary so you can navigate. The vertical columns represent families, or groups of elements, whereas the horizontal rows are called periods or series. You'll notice there are numbers above each group of elements. Since our focus is the representative elements, it's worth noting that these include groups 1A through 8A. You'll notice all of the groups belonging to the representative elements have an A after the group number. Sometimes periodic tables use roman numerals for group numbers, but we won't here.

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Coming up next: Alkali Metals (Group 1A Elements): Definition & Properties

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How Elements are Placed into Groups

So, what does the helium for your brother's balloon have in common with a neon sign? Both helium and neon are in group 8A (also known as noble gases, but we'll get to that shortly). Elements are grouped together because they share similar properties, in part due to their electrons, specifically valence electrons. Elements have protons and neutrons in their nucleus, or center, and electrons in a cloud surrounding the nucleus.

Valence electrons are the outermost electrons, or the electrons farthest away from the nucleus. These electrons help determine an element's properties. Remember I said the periodic table would help you organize all of the elements keeping you awake? Well, check this out.

Each group number for the representative elements corresponds to how many valence electrons an element has. So, all of the elements in group 2A have two valence electrons; all of the elements in group 5A have five valence electrons. Pretty neat, huh? Elements with different numbers of valence electrons behave quite differently from one another, so let's take a look at some of the different properties of each group.

Representative Elements Groups

We'll start our tour on the far left with group 1A, or the alkali metals. Although hydrogen appears to be in this group, it actually isn't. Hydrogen is a little confusing and is a bit of a misfit! You might have guessed it already, but the alkali metals have one valence electron, which makes them quite reactive (think: explosion)! In fact, they don't even exist in nature in their pure, elemental form because they quickly react, or combine, with another element to create something new. So you don't need to worry about the potassium in your banana; it won't make your stomach explode!

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