20 Science: Periodic Table of the Elements

Objective:

Students will learn the basic elements (pun intended) of the Periodic Table of the Elements and understand the basics of atoms and molecules.

Materials:

  • Lentils and Seeds in EHA packets
  • Periodic Table of the Elements Worksheet
  • Colored pencils or markers
  • Glue

If you have the ability and time, watch the video below with your classes.

 

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Directions:

The Periodic Table is a way of listing the elements. Elements are listed in the table by the structure of their atoms. This includes how many protons they have as well as how many electrons they have in their outer shell. From left to right and top to bottom, the elements are listed in the order of their atomic number, which is the number of protons in each atom.

 

Periodic Table of Elements
  • Ask your students to look at their little chart on the right and tell you how many protons are in H (Helium)? (the answer is one)
  • Ask you students to find the element with 79 protons.  (the answer is Au or gold)

Next, read most of the description below:

Why is it called the Periodic Table?

It is called “periodic” because elements are lined up in cycles or periods. From left to right elements are lined up in rows based on their atomic number (the number of protons in their nucleus). Some columns are skipped in order for elements with the same number of valence electrons to line up on the same columns. When they are lined up this way, elements in the columns have similar properties.

Each horizontal row in the table is a period. There are seven (or eight) total periods. The first one is short and only has two elements, hydrogen and helium. The sixth period has 32 elements. In each period the left most element has 1 electron in its outer shell and the right most element has a full shell.

Groups

Groups are the columns of the periodic table. There are 18 columns or groups and different groups have different properties.

One example of a group is the noble or inert gases. These elements all line up in the eighteenth or last column of the periodic table. They all have a full outer shell of electrons, making them very stable (they tend not to react with other elements). Another example is the alkali metals which all align on the left-most column. They are all very similar in that they have only 1 electron in their outer shell and are very reactive. You can see all the groups in the table below.

This lining-up and grouping of similar elements helps chemists when working with elements. They can understand and predict how an element might react or behave in a certain situation.

Element Abbreviations

Each element has its own name and abbreviation in the periodic table. Some of the abbreviations are easy to remember, like H for hydrogen. Some are a bit harder like Fe for iron or Au for gold. For gold the “Au” comes from the Latin word for gold “aurum”.

Who invented it?

The periodic table was proposed by Russian chemist Dmitri Mendeleev in 1869. Using the table, Mendeleev was able to accurately predict the properties of many elements before they were actually discovered.

Fun facts about the Periodic Table

  • Carbon is unique in that it is known to form up to 10 million different compounds. Carbon is important to the existence of life.
  • Francium is the rarest element on earth. There are probably no more than a few ounces of it on earth at any given time.
  • The only letter not in the periodic table is the letter J.
  • The country Argentina is named after the element silver (symbol Ag) which is argentum in Latin.
  • Although there is helium on Earth, it was first discovered by observing the sun.

 

Table at Top of Page:

  • Ask your students to color the LEFT side of their tables black, grey, gold, silver, or copper to signify metals.
  • Ask your students to color the RIGHT side  of their tables blue, yellow, or red to signify non-metals.

Magnesium Square:

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  • Students will copy this square.  Mg is the abbreviation for Magnesium.  It’s atomic number or number of protons is 12 and Magnesium’s relative atomic mass is 24.305.
Magnesium is one-third less dense than aluminium. It improves the mechanical, fabrication and welding characteristics of aluminium when used as an alloying agent. These alloys are useful in aeroplane and car construction.
Magnesium is used in products that benefit from being lightweight, such as car seats, luggage, laptops, cameras and power tools. It is also added to molten iron and steel to remove sulfur.
As magnesium ignites easily in air and burns with a bright light, it’s used in flares, fireworks and sparklers.
Magnesium sulfate is sometimes used as a mordant for dyes. Magnesium hydroxide is added to plastics to make them fire retardant. Magnesium oxide is used to make heat-resistant bricks for fireplaces and furnaces. It is also added to cattle feed and fertilisers. Magnesium hydroxide (milk of magnesia), sulfate (Epsom salts), chloride and citrate are all used in medicine.

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Students will copy this square.  C is the abbreviation for Carbon.  It’s atomic number or number of protons is 6 and Carbon’s relative atomic mass is 12.011.

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First Row:

  • Water is H20.  That means there are 2 Hydrogen atoms and one Oxygen atom. 
  • Ask your students to glue two of one color lentil on the first square and one of another color seed or lentil on the other square. 
  • For the third square, place the oxygen lentil on top and the two hydrogen lentils at it’s side but slightly down.  This is a water molecule!

Second Row:

  • Table salt is NaCl or one atom of sodium and one atom of chloride. 
  • Ask your students to glue one color of lentil  on the first square and the same amount of another color of lentil on the other. 
  • Now, ask your students to create table salt molecules by placing the same number of lentils together on the third square.  Remind your students that the ratio must be consistent.  There is only one sodium for each chloride. 

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