Key principles

The electrons on the outermost power level that the atom are dubbed valence electrons.The valence electrons are involved in bonding one atom to another.The attraction of every atom’s nucleus for the valence electrons of the various other atom traction the atom together. Together the attractions carry the atom together, electron from every atom space attracted come the cell core of both atoms, which “share” the electrons. The share of electrons between atoms is dubbed a covalent bond, i m sorry holds the atoms with each other as a molecule.A covalent bond happens if the attractions are solid enough in both atoms and if every atom has room because that 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 much more stable than they were as different atoms.


Students will certainly look at animations and also refer to the energy level models they have been making use of to make drawings of the process of covalent bonding. Students will think about why atoms bond to kind molecules prefer H2 (hydrogen), H2O (water), O2 (oxygen), CH4 (methane), and also CO2 (carbon dioxide).


Students will have the ability to explain that attraction in between the protons and also electrons of 2 atoms cause them to bond. College student will be able to draw a design of the covalent bonds between the atoms in H2 (hydrogen), H2O (water), O2 (oxygen), CH4 (methane), and CO2 (carbon dioxide).

You are watching: What parts of the atom are involved in chemical bonding?


Download the student task sheet, and distribute one every student once specified in the activity. The activity sheet will serve as the “Evaluate” component of each 5-E class plan.


Be certain you and also the college student wear appropriately fitting goggles.

Materials for Each Group

9-volt battery2 wires v alligator clips top top both ends2 pencils sharpened in ~ both endsWaterSaltClear plastic cupTape

About this lesson

This class will more than likely take an ext than one course period.


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

Project the picture Covalent shortcut in hydrogen.

Read much more about bonding in the added teacher background section at the finish of this lesson.

Note: This design of covalent bonding for the hydrogen molecule (H2) starts through 2 individual hydrogen atoms. In reality, hydrogen atom are never separate to begin with. They are constantly bonded v something else. To simplify the process, this design does not display the hydrogen atoms breaking your bonds from other atoms. It only focuses on the procedure of creating covalent bonds in between two hydrogen atoms.

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

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

There demands to it is in a solid enough attraction between the electrons of every atom because that the proton of the other atom. There requirements to be room in the outer power level of both atoms.

Once bonded, the hydrogen molecule is much more stable than the separation, personal, instance hydrogen atoms. Define to students that by being part of a covalent bond, the electron from each hydrogen atom gets to be close to two protons rather of only the one proton it began with. Since the electrons are closer to much more protons, the molecule of two bonded hydrogen atoms is more stable than the 2 individual unbonded hydrogen atoms.

This is why that is very rare to uncover a hydrogen atom that is no bonded to various other atoms. Hydrogen atoms bond with other hydrogen atoms to make hydrogen gas (H2). Or they can bond with various other atoms prefer oxygen to do water (H2O) or carbon to do methane (CH4) or many other atoms.

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

Have college student look in ~ their regular table of energy levels for elements 1–20 dispersed in lesson 3.

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

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

Give each student an task sheet.

Have students write a short caption under each picture to describe the procedure of covalent bonding and answer the an initial three questions. The rest of the task sheet will certainly either it is in completed together a class, in groups, or individually, relying on your instructions.

Ask students:

What go you write for the 2nd and third pictures the covalent bonding?Center drawing: as soon as two hydrogen atoms come nearby enough, their electrons are attracted come the proton the the various other atom. Last drawing: This brings the atoms close enough together that they re-superstructure electrons. What room two problems atoms must have actually in order to form covalent bonds v one another? there is a solid enough attraction in between atoms and also there is room for electrons in the outer energy level of both atoms.Why is a hydrogen molecule (H2) an ext stable than 2 individual hydrogen atoms?In the hydrogen molecule, the electrons from each atom are able to be close to two protons instead of only the one proton it started with. Whenever negative electrons room near added positive protons, the arrangement is much more stable.Why doesn’t a 3rd hydrogen atom join the H2 molecule to make H3? when two hydrogen atoms share your electrons v each other, your outer power levels space full.

You could explain come students that as soon as the outer power levels are full, share electrons with one more atom would certainly not happen for two key reasons:

An electron indigenous a brand-new atom would need to join one atom in the H2 molecule ~ above the next power level, additional from the nucleus whereby it would not feel a solid enough attraction.An electron indigenous an atom already in the H2 molecule and close come the cell nucleus would should move additional away to share v the brand-new atom.

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

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

Have students write a quick caption next to each picture to define the process of covalent bonding in the water molecule.

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

Note: This design of covalent bonding because that a water molecule starts with 2 separation, personal, instance hydrogen atoms and also 1 oxygen atom. In reality, this atoms are never ever separate to begin with. Lock are always bonded with something else. To leveling the process, this design does not present the hydrogen and also oxygen atom breaking your bonds from other atoms. The only focuses on the procedure of forming covalent binding 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 an oxygen atom share their electrons v each other, their outer energy levels room full.Explore

Have students use electrical power to rest the covalent bonds in water molecules.

Tell college student that electric energy can be offered to break the covalent binding in water molecules to produce hydrogen atoms and also oxygen atoms. Two hydrogen atoms climate bond to type hydrogen gas (H2) and also two oxygen atom bond to kind oxygen gas (O2).

You may select to perform this activity as a demonstration or present the video Electrolysis.

Question to investigate

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

Materials because that each group

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


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

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

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

Expected results

Bubbles will type and rise at first from one pencil lead. Soon, balloon will form and climb from the other. Students should be able to see the there is an ext of one gas 보다 the other. The gas that develops the small bubbles that comes off very first is hydrogen. The various other gas that creates the bigger bubbles and lags behind a little bit is oxygen.

Note: There will be bubbling as soon as hydrogen and also oxygen gas type on the pencil leads. Be certain students perform not obtain the misconception that the bubbles they see mean that the water is boiling. In boiling, the bond holding the atoms together in water molecules carry out not come apart. In the procedure of electrolysis, the binding holding the atom together carry out 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 was there an ext hydrogen gas developed than oxygen gas?Each water molecule breaks into 2 hydrogen atoms and also 1 oxygen atom. Two hydrogen atoms climate bond to type hydrogen gas (H2) and also 2 oxygen atoms bond to type oxygen gas (O2). Each water molecule has actually all the atoms essential to do 1 molecule that hydrogen gas. However with only 1 oxygen atom, a water molecule only has fifty percent of what is necessary to make 1 molecule of oxygen gas. So, 2 water molecule will develop 2 molecules of hydrogen gas but only 1 molecule the oxygen gas.Extend

Help students understand how atoms incorporate to kind the molecule of oxygen, methane, and carbon dioxide.

Remind students that in this lesson they looked in ~ the covalent bond in hydrogen molecules and also in water molecules. Phone call them that they will certainly look at the covalent bonds in 3 other common substances.

Project the computer animation Oxygen’s dual bond.

Explain come students that the oxygen molecules the are present in our air are comprised of 2 oxygen atoms. This computer animation will display them what the covalent bond in between 2 oxygen atoms is like. Narrate the computer animation by pointing out that each oxygen atom has 6 valence electrons. As soon as the oxygen atoms acquire close together, the attractions native the cell core of both atoms lure the external electrons. In this case, 2 electron from each atom space shared. This is referred to as a dual bond.

See more: How Many Calories In 4 Oz Cooked Salmon, Calories In 4 Oz Of Salmon

Each oxygen atom has 6 valence electrons in that outer energy levelWhen two oxygen atoms get close to each other, the attractions indigenous the nucleus of both atoms attract the outer electrons.