Key ideas

The electrons on the outermost energy level the the atom are dubbed valence electrons.The valence electron are associated in bonding one atom to another.The attraction of each atom’s nucleus because that the valence electron of the other atom traction the atoms together. As the attractions bring the atom together, electron from every atom are attracted to the cell core of both atoms, i beg your pardon “share” the electrons. The share of electrons between atoms is called a covalent bond, i m sorry holds the atoms with each other as a molecule.A covalent bond happens if the attractions are strong enough in both atoms and if each atom has actually room for an electron in its outer power level.Atoms will certainly covalently bond until their outer energy level is full.Atoms covalently bonded as a molecule are an ext stable 보다 they to be as different atoms.


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


Students will be able to explain the attraction between the protons and electrons of 2 atoms reason them to bond. College student will be able to draw a version 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 every student once specified in the activity. The activity sheet will certainly serve together the “Evaluate” ingredient of every 5-E class plan.


Be sure you and also the student wear effectively fitting goggles.

Materials for Each Group

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

About this lesson

This class will probably take much more than one course period.


Discuss the conditions needed for covalent bonding and the steady molecule that is formed.

Project the image Covalent bond in hydrogen.

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

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

Two hydrogen atoms are close to each other.When 2 hydrogen atom come close enough to every other, their electrons space attracted to the proton the the various other atom.Because over there is both a strong enough attraction betweeen atoms and also room for electrons in the outer power level that both atoms, the atoms share electrons. This forms a covalent bond.

Tell students the there space two key reasons why 2 hydrogen atom bond with each other to do one hydrogen molecule:

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

Once bonded, the hydrogen molecule is more stable than the individual hydrogen atoms. Explain to students the by being part of a covalent bond, the electron from every hydrogen atom gets to be near two protons instead of just the one proton it began with. Since the electrons are closer to an ext protons, the molecule of two bonded hydrogen atoms is an ext stable 보다 the two individual unbonded hydrogen atoms.

This is why that is an extremely rare to find a hydrogen atom that is not bonded to various other atoms. Hydrogen atoms bond with other hydrogen atom to do hydrogen gas (H2). Or they deserve to bond with other atoms like oxygen to do water (H2O) or carbon to make methane (CH4) or plenty of other atoms.

Show student that when two hydrogen atoms bond together, the outer power level becomes full.

Have student look at their regular table of energy levels for elements 1–20 spread in class 3.

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

Have students explain covalent bonding in a hydrogen molecule ~ above their activity sheet and then testimonial their answers.

Give each student an activity sheet.

Have students create a quick caption under each photo to explain the process of covalent bonding and answer the an initial three questions. The remainder of the task sheet will certainly either it is in completed as a class, in groups, or individually, relying on your instructions.

Ask students:

What walk you create for the second and third pictures the covalent bonding?Center drawing: as soon as two hydrogen atom come near enough, your electrons room attracted come the proton that the various other atom. Critical drawing: This bring the atom close sufficient together that they re-superstructure electrons. What space two conditions atoms must have actually in order to type covalent bonds v one another? there is a strong enough attraction in between atoms and there is room for electrons in the outer power level that both atoms.Why is a hydrogen molecule (H2) more stable than two individual hydrogen atoms?In the hydrogen molecule, the electrons from each atom room able to be near two protons instead of only the one proton it began with. Whenever an adverse electrons room near additional positive protons, the setup is an ext stable.Why doesn’t a third hydrogen atom join the H2 molecule to make H3? once two hydrogen atom share their electrons v each other, your outer power levels room full.

You can explain come students that as soon as the outer power levels space full, sharing electrons with an additional atom would not occur for two main reasons:

An electron from a new atom would need to join an atom in the H2 molecule on the next energy level, additional from the nucleus where it would certainly not feel a strong enough attraction.An electron native an atom already in the H2 molecule and also close to the cell core would need to move additional away come share v the brand-new atom.

Both of this possibilities would make the molecule less stable and also would no happen.

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

Have students compose a quick caption alongside each snapshot to explain the process of covalent bonding in the water molecule.

Two hydrogen atoms and one oxygen atoms are near each other.When two hydrogen atom come close enough to one oxygen atoms, your electrons are attracted to the proton the the various other atom.Because over there is both a solid enough attraction in between atoms and also room for electrons in the outer power levels of the atoms, castle share electrons. This creates a covalent bond.

Note: This model of covalent bonding because that a water molecule starts with 2 individual hydrogen atoms and 1 oxygen atom. In reality, these atoms are never separate to begin with. They are always bonded v something else. To simplify the process, this design does not show the hydrogen and also oxygen atom breaking your bonds from other atoms. It only concentrates on the process of forming covalent bond to do 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 your electrons with each other, your outer energy levels room full.Explore

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

Tell students that electrical energy have the right to be offered to rest the covalent bonds in water molecules to develop hydrogen atoms and oxygen atoms. Two hydrogen atoms then bond to form hydrogen gas (H2) and two oxygen atoms bond to kind oxygen gas (O2).

You may choose to do this task as a show or present the video clip Electrolysis.

Question to investigate

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

Materials because that each group

9-volt battery2 wires with alligator clips ~ above 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 much more than half-way up.

With the assist of a partner, wrap tape approximately the pencils and also battery as shown.

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

Expected results

Bubbles will form and rise initially from one pencil lead. Soon, balloon will type and rise from the other. Students should have the ability to see that there is an ext of one gas than the other. The gas that forms the tiny bubbles the comes off an initial is hydrogen. The various other gas that creates the larger bubbles and lags behind a little bit is oxygen.

Note: There will certainly be bubbling once hydrogen and oxygen gas form on the pencil leads. Be sure students perform not gain the misconception that the balloon they see typical that the water is boiling. In boiling, the binding holding the atoms together in water molecules execute not come apart. In the process of electrolysis, the binding holding the atoms together carry out come apart.

Discuss college student observations.

Ask students:

What room the balloon made out of in the activity?Hydrogen gas (H2) and oxygen gas (O2)Why was there more hydrogen gas produced than oxygen gas?Each water molecule breaks right into 2 hydrogen atoms and also 1 oxygen atom. 2 hydrogen atoms climate bond to type hydrogen gas (H2) and 2 oxygen atoms bond to form oxygen gas (O2). Every water molecule has all the atoms essential to make 1 molecule the hydrogen gas. But with only 1 oxygen atom, a water molecule just has fifty percent of what is required to do 1 molecule that oxygen gas. So, 2 water molecules will create 2 molecule of hydrogen gas yet only 1 molecule of oxygen gas.Extend

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

Remind students the in this lesson lock looked in ~ the covalent binding in hydrogen molecules and also in water molecules. Tell them that they will look at the covalent binding in 3 other common substances.

Project the animation Oxygen’s dual bond.

Explain come students the the oxygen molecules that are present in our air are comprised of 2 oxygen atoms. This animation will show them what the covalent bond between 2 oxygen atom is like. Narrate the animation by pointing out that each oxygen atom has 6 valence electrons. When the oxygen atoms acquire close together, the attractions from the cell nucleus of both atoms lure the outer electrons. In this case, 2 electron from every atom space shared. This is called a double bond.

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Each oxygen atom has 6 valence electrons in that is outer energy levelWhen 2 oxygen atoms obtain close to each other, the attractions native the cell nucleus of both atoms entice the outer electrons.