Key Concepts:

A physical change, such as a state readjust or dissolving, go not create a brand-new substance, but a chemical adjust does.In a chemical reaction, the atoms and molecules that communicate with each other are referred to as reactants.In a chemistry reaction, the atoms and also molecules created by the reaction are dubbed products. In a chemical reaction, just the atoms present in the reactants can finish up in the products. No new atoms are created, and also no atoms room destroyed.In a chemical reaction, reactants call each other, bonds between atoms in the reactants space broken, and atoms rearrange and type new bonds to do the products.

You are watching: What part of an atom is involved in a chemical reaction?


The teacher will usage a small candle flame to show a chemistry reaction in between the candle wax and oxygen in the air. Students will check out a molecular animation of the burning of methane and also oxygen as a design of a comparable reaction. Students will usage atom design cut-outs to design the reaction and also see the all the atoms in the reactants show up in the products.


Students will have the ability to explain the for a chemical reaction to take place, the bonds between atoms in the reactants space broken, the atoms rearrange, and brand-new bonds in between the atom are created to do the products. Student will additionally be maybe to explain that in a chemical reaction, no atom are created or destroyed.


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” ingredient of each 5-E great plan.


Be sure you and also the college student wear correctly fitting goggles. Be mindful when lighting the candle. Be certain that the match and also candle are fully extinguished when you room finished with the demonstration.

Materials because that the Demonstration

Tea irradiate candle or other little stable candle MatchesGlass jar, big enough come be inserted over the candle

Materials for Each Student

Atom cut-outs from the activity sheetSheet of colored record or construction paperColored pencilsScissorsGlue or tape

Review what happens throughout a physical readjust and present the idea of chemistry change.

Tell students the in ahead chapters they have studied different facets of physical change. When atoms and molecules rate up or slow down, the is a physics change. Once they readjust state from liquid to heavy or from gas to liquid, that is a physics change. Once a problem is liquified by water or some other solvent, a brand-new substance has not really been formed. The ion or molecules have the right to still come ago together to type the initial substance.

Let students understand that in this thing they will discover what happens throughout a chemistry change. In a chemical change, the atoms in the reaction rearrange themselves and also bond together in different way to kind one or much more new commodities with different qualities than the reactants. As soon as a new substance is formed, the adjust is called a chemistry change.

As a demonstration, irradiate a candle and also explain what is happening utilizing the terms reactants, products, and also chemical reaction.

Explain the in most chemical reactions, two or an ext substances, referred to as reactants, connect to produce different substances referred to as products. Tell students that burning a candle is an example of a chemical reaction.

Materials because that the Demonstration

Tea irradiate candle or other little stable candle MatchesGlass jar, huge enough come be placed over the candle


Carefully irradiate a tea light candle or other small candle.Keep the candle burning together you ask students the questions below. You will placed the candle out in the second component of the demonstration.

Expected results

The wick will catch on fire and also the flame will certainly be sustained by the chemical reaction.

The complying with question is not easy and students space not meant to know the answer in ~ this point. However, thinking around a candle burning in regards to a chemistry reaction is a good place to start developing what it way when substances react chemically.

Ask students:

What carry out you think space the reactants in this chemical reaction? Wax and also oxygen native the air are the reactants.

Students often say the the cable or wick is burning. It is true that the string of the wick walk burn yet it’s the wax on the string and also not so lot the cable itself that burns and also keeps the candle burning. Explain that the molecule that make up the wax combine with oxygen indigenous the air to do the assets carbon dioxide and water vapor.

Point the end to students that this is just one of the major characteristics of a chemistry reaction: In a chemical reaction, atom in the reactants integrate in brand-new and different ways to form the molecule of the products.

Students may be surprised that water can be developed from combustion. Since we use water come extinguish a fire, it may seem strange the water is actually produced by combustion. You may want come let students recognize that when they “burn” food in their bodies, they also produce carbon dioxide and also water.

Place a jar over the candle to aid students realize that oxygen is a reactant in the burn of a candle.

Remind students the air is a mixture the gases. Define that once something burns, the reacts v the oxygen in the air.

Ask college student to make a prediction:

Will the candle tho burn if among the reaction (wax or oxygen) is no longer available? Students may guess that the candle will certainly not burn due to the fact that both reactants are required for the chemical reaction to continue.


Carefully location a glass jar end the lit candle.


Expected Results

The fire goes out.

Ask students:

Why carry out you think the fire goes out when we put a jar over the candle? placing a jar over the candle borders the quantity of oxygen in the air approximately the candle. Without sufficient oxygen to react with the wax, the chemical reaction cannot take it place and also the candle can not burn. Once a candle burns for a while, it at some point gets smaller and also smaller. Wherein does the candle wax go? as soon as a candle burns, the candle wax seems to “disappear.” it doesn’t really disappear, though: It reacts chemically, and also the new products go into the air.

Note: some curious students might ask what the flame is do of. This is a good question and also not trivial to answer. The flame is burn wax vapor. The irradiate of the fire is caused by a process called chemiluminescence. Power released in the chemistry reaction provides electrons from various molecules relocate to a greater energy state. When the electron come earlier down, energy is exit in the kind of light.


Have students make a version to show that in a chemistry reaction the atom of the reaction rearrange to type the products.

Question to Investigate

Where carry out the atoms in the products of a chemistry reaction come from?

Materials because that Each Student

Atom model cut-outs (carbon, oxygen, and hydrogen)Sheet the colored record or construction paperColored pencilsScissorsGlue or tape


Prepare the AtomsColor the carbon atom black, the oxygen atoms red, and leave the hydrogen atoms white. Usage scissors to carefully cut out the atoms.Build the Reactants

On a paper of paper, location the atoms together to do the molecules of the reactants on the left next of the chemistry equation because that the burning of methane.

Write the chemical formula under every molecule the the reactants. Additionally draw a + sign between the reactants.

After you room sure the students have actually made and written the formula for the reactant molecules, tell students that they will certainly rearrange the atoms in the reaction to kind the products.

Build the ProductsDraw an arrow after the 2nd oxygen molecule to show that a chemical reaction is acquisition place.Rearrange the atom in the reactants to make the molecules in the products on the ideal side that the arrow. Create the chemical formula under each molecule the the products. Also draw a + sign between the products.

Tell students the in a chemistry reaction, the atom in the reaction come apart, rearrange, and make brand-new bonds to kind the products.

Represent the chemistry EquationHave students usage their continuing to be atoms to do the reactants again to stand for the chemical reaction together a complete chemical equation. Glue or tape the atoms to the file to do a much more permanent chemistry equation of the burning of methane.Extend

Introduce two other combustion reactions and also have students check to see whether or not they space balanced.

Tell student that, in addition to the wax and also methane, part other common hydrocarbons room propane (the fuel in outdoor gas grills), and butane (the fuel in disposable lighters). Have students counting the variety of carbon, hydrogen, and also oxygen atoms in the reactants and products of every equation to see if the equation is balanced. They should record the number of each type of atom in the graph on their activity sheet.

See more: How Long Is Opened Chicken Broth Good For, Does Chicken Broth Go Bad


Lighting an the end gas grill—Combustion that propane

C3H8 + 5O2 → 3CO2 + 4H20

Using a disposable lighter—Combustion the butane

2C4H10 + 13O2 → 8CO2 + 10H2O

After students have counted up each form of atom, review their answers to make certain they know just how to translate subscripts and also coefficients.