Key concepts

The electron on the outermost power level the the atom are called valence electrons.The valence electrons are affiliated in bonding one atom come another.The attraction of every atom’s nucleus because that the valence electron of the various other atom pulls the atom together. As the attractions lug the atom together, electron from every atom are attracted to the cell nucleus of both atoms, i m sorry “share” the electrons. The share of electrons between atoms is referred to as a covalent bond, which holds the atoms together as a molecule.A covalent bond happens if the attractions are strong enough in both atoms and if every atom has room because that an electron in that outer power level.Atoms will certainly covalently bond until their outer power level is full.Atoms covalently bonded as a molecule are much more stable 보다 they to be as different atoms.


Students will certainly look at animations and refer come the power level models they have been utilizing to make illustrations of the procedure of covalent bonding. College student will take into consideration why atoms bond to form molecules like H2 (hydrogen), H2O (water), O2 (oxygen), CH4 (methane), and CO2 (carbon dioxide).


Students will be able to explain that attraction in between the protons and electrons of two atoms cause them come bond. Students will be able to draw a model of the covalent bonds 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 every student once specified in the activity. The task sheet will serve as the “Evaluate” ingredient of each 5-E lesson plan.


Be certain you and also the students wear correctly fitting goggles.

Materials because that Each Group

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

About this lesson

This lesson will more than likely take much more than one course period.


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

Project the picture Covalent shortcut in hydrogen.

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

Note: This design of covalent bonding because that the hydrogen molecule (H2) starts through 2 individual hydrogen atoms. In reality, hydrogen atoms are never separate to begin with. Castle are constantly bonded with something else. To leveling the process, this design does not display the hydrogen atoms breaking your bonds from other atoms. It only concentrates on the process of developing covalent bonds in between two hydrogen atoms.

Two hydrogen atom are near each other.When 2 hydrogen atoms come close enough to each other, their electrons space attracted come the proton that the other atom.Because over there is both a solid enough attraction betweeen atoms and also room because that electrons in the outer energy level of both atoms, the atom share electrons. This creates a covalent bond.

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

There demands to be a solid enough attraction in between the electrons of every atom for the protons of the other atom. There needs to be room in the outer energy level that both atoms.

Once bonded, the hydrogen molecule is much more stable than the separation, personal, instance hydrogen atoms. Describe to students the by being part of a covalent bond, the electron from every hydrogen atom it s okay to be close to two protons instead of only the one proton it began with. Because the electrons space closer to an ext protons, the molecule of 2 bonded hydrogen atoms is an ext stable 보다 the 2 individual unbonded hydrogen atoms.

This is why it is really rare to discover a hydrogen atom the is not bonded to other atoms. Hydrogen atom bond with various other hydrogen atom to make hydrogen gas (H2). Or they have the right to bond with various other atoms prefer oxygen to make water (H2O) or carbon to make methane (CH4) or numerous other atoms.

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

Have student look at their regular table of power levels for facets 1–20 spread in great 3.

Explain that the two electrons in the hydrogen molecule (H2) deserve to be thought of as “belonging” to each atom. This way that every hydrogen atom now has two electrons in its first energy level. The very first energy level in the outer power level because that hydrogen and also can only accommodate or “hold” two electrons. Atom will proceed to covalently bond until their outer power levels are full. In ~ this point, extr atoms will certainly not covalently bond come the atom in the H2 molecule.

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

Give each student an activity sheet.

Have students write a brief caption under each photo to describe the procedure of covalent bonding and also answer the very first three questions. The rest of the task sheet will either be completed as a class, in groups, or individually, relying on your instructions.

Ask students:

What did you write for the second and third pictures of covalent bonding?Center drawing: when two hydrogen atoms come close enough, your electrons are attracted come the proton the the other atom. Critical drawing: This brings the atom close sufficient together the they share electrons. What are two problems atoms must have in order to form covalent bonds with one another? there is a strong enough attraction between atoms and also there is room for electrons in the outer power level of both atoms.Why is a hydrogen molecule (H2) an ext stable than two individual hydrogen atoms?In the hydrogen molecule, the electron from every atom space able to be close to two protons instead of just the one proton it began with. Whenever negative electrons space near added positive protons, the plan is more stable.Why doesn’t a third hydrogen atom sign up with the H2 molecule to do H3? when two hydrogen atom share your electrons with each other, their outer power levels are full.

You could explain to students that when the outer energy levels space full, sharing electrons with an additional atom would not happen for two main reasons:

An electron native a brand-new atom would need to join an atom in the H2 molecule ~ above the next energy level, additional from the nucleus wherein it would certainly not feeling a strong enough attraction.An electron indigenous an atom currently in the H2 molecule and close come the cell nucleus would should move additional away come share v the brand-new atom.

Both of these possibilities would certainly make the molecule less stable and also would not happen.

Have students describe covalent bonding in a water molecule on their activity sheet.

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

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

Note: This model of covalent bonding for a water molecule starts v 2 separation, personal, instance hydrogen atoms and also 1 oxygen atom. In reality, these atoms are never ever separate to start with. Lock are constantly bonded through something else. To leveling the process, this model does not display the hydrogen and also oxygen atom breaking their bonds from other atoms. The only focuses on the procedure of developing covalent binding to do water.

Ask students:

Why can’t a third hydrogen atom sign up with the water molecule (H20) to do H3O? once two hydrogen atoms and an oxygen atom share your electrons through each other, your outer power levels space full.Explore

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

Tell student that electric energy can be provided to break the covalent binding in water molecule to develop hydrogen atoms and also oxygen atoms. Two hydrogen atoms then bond to kind hydrogen gas (H2) and two oxygen atoms bond to form oxygen gas (O2).

You may select to execute this task as a show or present the video clip Electrolysis.

Question come investigate

What is created when the covalent link in water molecule is broken?

Materials because that each group

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


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

With the assist of a partner, plunder tape around the pencils and battery as shown.

Add water to a clean plastic cup until it is around ½-full. Add around ½ teaspoon of Epsom salt to the water and stir till the salt dissolves. Affix one alligator clip come one terminal that the battery.Using the various other wire, affix one alligator clip to the various other terminal the the battery.Connect one end of the pencil bring about the alligator clip in ~ the end of among the wires.Using the various other wire, connect one finish of the various other pencil result in the alligator clip in ~ the end of the wire.Place the end of the pencil into the water together shown.

Expected results

Bubbles will kind and rise initially from one pencil lead. Soon, balloon will form and rise from the other. Students should be able to see the there is much more of one gas than the other. The gas that develops the little bubbles the comes off an initial is hydrogen. The other gas that develops the larger bubbles and also lags behind a bit is oxygen.

Note: There will be bubbling as soon as hydrogen and also oxygen gas form on the pencil leads. Be certain students carry out not acquire the misconception the the bubbles they see average that the water is boiling. In boiling, the bond holding the atoms with each other in water molecules carry out not come apart. In the procedure of electrolysis, the bond holding the atoms together execute come apart.

Discuss student observations.

Ask students:

What space the balloon made the end of in the activity?Hydrogen gas (H2) and oxygen gas (O2)Why was there much more hydrogen gas created than oxygen gas?Each water molecule breaks into 2 hydrogen atoms and 1 oxygen atom. 2 hydrogen atoms climate bond to form hydrogen gas (H2) and 2 oxygen atoms bond to type oxygen gas (O2). Each water molecule has actually all the atoms essential to make 1 molecule the hydrogen gas. But with only 1 oxygen atom, a water molecule only has half of what is essential to do 1 molecule of oxygen gas. So, 2 water molecule will create 2 molecules of hydrogen gas yet only 1 molecule the oxygen gas.Extend

Help college student understand exactly how atoms integrate to form the molecule of oxygen, methane, and also carbon dioxide.

Remind students the in this lesson castle looked in ~ the covalent binding in hydrogen molecules and also in water molecules. Tell them the they will certainly look in ~ the covalent bond in three other common substances.

Project the computer animation Oxygen’s twin bond.

Explain to students the the oxygen molecules that are current in our air are made up of 2 oxygen atoms. This computer animation will present them what the covalent bond between 2 oxygen atom is like. Narrate the animation by discussing that each oxygen atom has 6 valence electrons. When the oxygen atoms obtain close together, the attractions from the cell core of both atoms attract the outer electrons. In this case, 2 electrons from every atom are shared. This is referred to as a dual bond.

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Each oxygen atom has 6 valence electrons in its outer power levelWhen 2 oxygen atoms obtain close to every other, the attractions from the cell core of both atoms attract the external electrons.