Key principles

The electron on the outermost power level of the atom are referred to as valence electrons.The valence electron are connected in bonding one atom come another.The attraction of each atom’s nucleus because that the valence electron of the other atom pulls the atoms together. As the attractions bring the atoms together, electron from each atom room attracted to the nucleus of both atoms, i m sorry “share” the electrons. The share of electrons between atoms is dubbed a covalent bond, which holds the atoms together as a molecule.A covalent bond wake up if the attractions are strong enough in both atoms and if every atom has room because that an electron in its outer power level.Atoms will covalently bond till their outer power level is full.Atoms covalently bonded as a molecule are much more stable than they were as separate atoms.


Students will look at animations and refer to the energy level models they have been making use of to make illustrations of the process of covalent bonding. Student will take into consideration why atom bond to type molecules prefer H2 (hydrogen), H2O (water), O2 (oxygen), CH4 (methane), and also CO2 (carbon dioxide).


Students will have the ability to explain the attraction between the protons and also electrons of two atoms reason them come bond. Students will be able to draw a design of the covalent bonds in between the atoms in H2 (hydrogen), H2O (water), O2 (oxygen), CH4 (methane), and also CO2 (carbon dioxide).

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Download the student activity sheet, and also distribute one per student when specified in the activity. The activity sheet will certainly serve as the “Evaluate” component of every 5-E great plan.


Be sure you and the students wear correctly fitting goggles.

Materials for Each Group

9-volt battery2 wires through alligator clips top top both ends2 pencils sharpened at both endsWaterSaltClear plastic cupTape

About this lesson

This class will probably take more than one course period.


Discuss the conditions needed for covalent bonding and also the stable molecule the is formed.

Project the picture Covalent shortcut in hydrogen.

Read more about bonding in the extr teacher background ar at the finish of this lesson.

Note: This model of covalent bonding for the hydrogen molecule (H2) starts v 2 separation, personal, instance hydrogen atoms. In reality, hydrogen atom are never ever separate to begin with. They are constantly bonded through something else. To simplify the process, this version does not show the hydrogen atoms breaking their bonds from other atoms. That only focuses on the process of forming covalent bonds between two hydrogen atoms.

Two hydrogen atoms are near each other.When two hydrogen atoms come close sufficient to every other, their electrons are attracted come the proton of the various other atom.Because over there is both a solid enough attraction betweeen atoms and also room because that electrons in the outer energy level that both atoms, the atom share electrons. This forms a covalent bond.

Tell students that there are two main reasons why two hydrogen atoms bond together to do one hydrogen molecule:

There requirements to be a solid enough attraction in between the electrons of each atom for the proton of the various other atom. There needs to it is in room in the outer power level of both atoms.

Once bonded, the hydrogen molecule is much more stable than the individual hydrogen atoms. Explain to students the by being part of a covalent bond, the electron from each hydrogen atom it s okay to be near two protons rather of only the one proton it began with. Because the electrons space closer to much more protons, the molecule of two bonded hydrogen atoms is more stable than the two individual unbonded hydrogen atoms.

This is why the is an extremely rare to find a hydrogen atom the is not bonded to various other atoms. Hydrogen atoms bond with various other hydrogen atoms to make hydrogen gas (H2). Or they have the right to bond with other atoms choose oxygen to make water (H2O) or carbon to make methane (CH4) or many other atoms.

Show student that once two hydrogen atoms bond together, the outer energy level i do not care full.

Have student look in ~ their regular table of energy levels for facets 1–20 dispersed in class 3.

Explain the the 2 electrons in the hydrogen molecule (H2) have the right to be assumed of together “belonging” to each atom. This way that each hydrogen atom now has two electrons in its very first energy level. The first energy level in the outer power level because that hydrogen and can just accommodate or “hold” two electrons. Atoms will proceed to covalently bond till their outer power levels are full. In ~ this point, added atoms will not covalently bond come the atom in the H2 molecule.

Have students explain covalent bonding in a hydrogen molecule on their task sheet and also then evaluation their answers.

Give each college student an task sheet.

Have students write a quick caption under each snapshot to explain the procedure of covalent bonding and also answer the first three questions. The remainder of the activity sheet will either it is in completed together a class, in groups, or individually, relying on your instructions.

Ask students:

What did you create for the second and 3rd pictures of covalent bonding?Center drawing: once two hydrogen atom come close enough, their electrons are attracted to the proton of the various other atom. Last drawing: This bring the atom close sufficient together the they re-publishing electrons. What space two conditions atoms must have in stimulate to kind covalent bonds through one another? there is a solid enough attraction in between atoms and also there is room because that electrons in the outer energy level the both atoms.Why is a hydrogen molecule (H2) more stable than 2 individual hydrogen atoms?In the hydrogen molecule, the electron from every atom space able come be close to two protons instead of only the one proton it started with. Whenever an adverse electrons space near additional positive protons, the plan is much more stable.Why doesn’t a third hydrogen atom sign up with the H2 molecule to make H3? when two hydrogen atoms share your electrons through each other, your outer energy levels room full.

You might explain come students that as soon as the outer power levels are full, share electrons with one more atom would not occur for two main reasons:

An electron native a new atom would have to join an atom in the H2 molecule ~ above the next power level, more from the nucleus whereby it would not feeling a strong enough attraction.An electron native an atom currently in the H2 molecule and close to the nucleus would should move additional away to share v the brand-new atom.

Both of this possibilities would certainly make the molecule much less stable and would not happen.

Have students define covalent bonding in a water molecule on their task sheet.

Have students compose a short caption beside each picture to define the process of covalent bonding in the water molecule.

Two hydrogen atoms and also one oxygen atoms are close to each other.When 2 hydrogen atom come close enough to an oxygen atoms, their electrons room attracted to the proton the the other atom.Because there is both a strong enough attraction between atoms and room because that electrons in the outer energy levels that the atoms, castle share electrons. This forms a covalent bond.

Note: This model of covalent bonding because that a water molecule starts through 2 separation, personal, instance hydrogen atoms and also 1 oxygen atom. In reality, these atoms are never separate to start with. They are constantly bonded v something else. To leveling the process, this model does not display the hydrogen and oxygen atoms breaking your bonds from various other atoms. The only concentrates on the process of forming covalent bonds to make water.

Ask students:

Why can’t a 3rd hydrogen atom sign up with the water molecule (H20) to do H3O? when two hydrogen atoms and also an oxygen atom share their electrons v each other, their outer power levels are full.Explore

Have college student use electrical energy to rest the covalent binding in water molecules.

Tell students that electric energy deserve to be supplied to break the covalent binding in water molecule to create hydrogen atoms and oxygen atoms. Two hydrogen atoms then bond to kind hydrogen gas (H2) and also two oxygen atom bond to type oxygen gas (O2).

You may choose to carry out this activity as a show or show the video clip Electrolysis.

Question come investigate

What is developed when the covalent bond in water molecules is broken?

Materials for each group

9-volt battery2 wires v alligator clips top top both ends2 pencils sharpened at both endsWaterEpsom salt (magnesium sulfate)Clear plastic cupTape


Place a battery between 2 pencils. Be sure that the battery is much more than half-way up.

With the aid of a partner, plunder tape about the pencils and also battery as shown.

Add water to a clear plastic cup till it is about ½-full. Add about ½ tespoon of Epsom salt to the water and also stir till the salt dissolves. Connect one alligator clip to one terminal of the battery.Using the various other wire, attach one alligator clip come the various other terminal of the battery.Connect one finish of the pencil lead to the alligator clip at the finish of one of the wires.Using the other wire, connect one finish of the other pencil lead to the alligator clip at the end of the wire.Place the ends of the pencil into the water as shown.

Expected results

Bubbles will form and rise originally from one pencil lead. Soon, bubbles will form and rise from the other. Student should have the ability to see the there is more of one gas than the other. The gas that forms the little bubbles the comes off very first is hydrogen. The other gas that forms the bigger bubbles and lags behind a little is oxygen.

Note: There will be bubbling as soon as hydrogen and also oxygen gas type on the pencil leads. Be sure students carry out not acquire the misconception the the balloon they see average that the water is boiling. In boiling, the bonds holding the atoms with each other in water molecules perform not come apart. In the process of electrolysis, the bonds holding the atom together execute come apart.

Discuss college student observations.

Ask students:

What are the balloon made out of in the activity?Hydrogen gas (H2) and oxygen gas (O2)Why to be there an ext hydrogen gas developed than oxygen gas?Each water molecule breaks into 2 hydrogen atoms and 1 oxygen atom. 2 hydrogen atoms climate bond to kind hydrogen gas (H2) and 2 oxygen atoms bond to type oxygen gas (O2). Every water molecule has actually all the atoms required to make 1 molecule the hydrogen gas. Yet with just 1 oxygen atom, a water molecule just has fifty percent of what is needed to do 1 molecule of oxygen gas. So, 2 water molecules will create 2 molecules of hydrogen gas but only 1 molecule of oxygen gas.Extend

Help students understand exactly how atoms incorporate to form the molecules of oxygen, methane, and carbon dioxide.

Remind students the in this lesson lock looked at the covalent binding in hydrogen molecules and in water molecules. Phone call them that they will look in ~ the covalent bonds in 3 other typical substances.

Project the computer animation Oxygen’s double bond.

Explain to students that the oxygen molecules that are current in our air are made up of 2 oxygen atoms. This computer animation will display them what the covalent bond in between 2 oxygen atom is like. Narrate the animation by stating that every oxygen atom has 6 valence electrons. As soon as the oxygen atoms get close together, the attractions from the cell nucleus of both atoms entice the outer electrons. In this case, 2 electrons from every atom space shared. This is referred to as a dual bond.

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Each oxygen atom has 6 valence electrons in that outer energy levelWhen two oxygen atoms acquire close to each other, the attractions native the cell core of both atoms lure the external electrons.