Chemistry Class - Covalent Bonds - Homeschool Science Chemistry

Today we are looking closer at covalent bonds! This is the sixth lesson in the homeschool science Chemistry Class I am putting together for elementary and middle school aged students! Click HERE to see all the other lessons too!



Yesterday we talked about how covalent bonds hold molecules together because the atoms inside the molecule "share" the electrons. For example, the electrons in water go around both the hydrogen atoms and the oxygen atom. Today we are going to break those covalent bonds with electricity!


Supplies: 

* beaker or bowl
* water
* salt
* 9 volt battery
* 2 alligator clips




Goals:
At the end of this lesson, students will be able to...
1- Explain what a molecule is.
2- Explain what a covalent bond is.
3- Give an example of a molecule held together by covalent bonds.
4- Tell how many and which atoms are in a molecule if they are given the molecules chemical formula.


Lesson:

Read: Today we're going to start out with an experiment! We're going to pass electricity through water to break the covalent bonds that hold the oxygen and hydrogen atoms together!

Fill the bowl about half full with water and add about 3 or 4 tablespoons of salt to the bowl. Stir for 3 or 4 minutes, dissolving as much as possible. The salt makes it easy to conduct electricity through the water--we'll talk about that more tomorrow. ;)

Clip one end of one alligator clip on the positive end of the battery and one end of the other alligator clip on the negative end of the battery. Then gently set the other ends of each clip in the bowl of water, not touching each other. I like to hold the clips about half way out of the water too so that you can see the reaction better.




After a minute or two you should start to notice bubbles around the alligator clips!



What's going on?

Remember what water's chemical formula is?

H2O

It means that every molecule of water has two hydrogen atoms and one oxygen atom. All three are bound together because they are sharing electrons so that each atom can have a full energy level.

The electricity is strong enough that it breaks apart the hydrogen and oxygen. Each hydrogen atom immediately combines with another hydrogen atom to form H2 (a gas) and each oxygen atom combines with another oxygen atom to form O2 (also a gas).

We write this process like this:

2H2O --> 2H2 + O2

You can "read" this chemical equation by saying "Two water molecules break apart to give you two hydrogen molecules and one oxygen molecule."

You can see an animation of each of these molecules forming HERE, as well as a video of the experiment (they clipped their alligator clips on sharpened pencils)...just use the arrows on the "slideshow" to scroll to each different animation.

Did you notice there were more bubbles on one of your alligator clips than on the other one? Look at the chemical equation again. Which molecule do you make the most of when you split the water apart? It is hydrogen! There are two hydrogen molecules for every one oxygen molecule made, so you can see more of them collecting on your alligator clip!

What type of bond do you think holds the hydrogen and oxygen molecules together?  These molecules also use covalent bonds!


Review/Final Discussion:

1- What is an atom?
2- What is a molecule?
3- What is a covalent bond?
4- Give an example of a molecule held together by covalent bonds?
5- The chemical formula for water is H2O. How many hydrogen atoms are in each molecule of water? How many oxygen atoms?
6- The chemical formula for sucrose (also known as table sugar) is C12H22O11. How many carbon atoms are in a molecule of sucrose?
7- How many hydrogen atoms are in two molecules of sucrose (written 2C12H22O11)?

Review Answers: 
1- An atom is the smallest particle of matter that still behaves like that matter.
2- A molecule is a group of 2 or more atoms.
3- A covalent bond is a bond that joins atoms by sharing their electrons.
4- Water (H2O)
5- Two hydrogen atoms and one oxygen atom are in each molecule of water.
6- 12
7- 44

***

This is the sixth lesson in my Atoms & Molecules Chemistry Class for homeschoolers!  Click HERE to get the rest!






And if you're looking for more homeschool unit studies, be sure to check out our growing collection here!



Happy Educating,
Carla & the kids who don't sit still!





And if you're looking for more homeschool unit studies, be sure to check out our growing collection here!



Happy Educating,
Carla & the kids who don't sit still!

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