Basic Types of Chemical Reactions

By Carlyn Main
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Chemistry sets are designed to demonstrate both the properties and reactions of different chemicals. In our lineup of the best chemistry sets, many kits have  sole purpose is to identify chemicals based on different properties. But when most people think of chemistry, they imagine someone in a long white coat and big plastic goggles, pouring small amounts of one chemical into another and then watching an impressive reaction take place. This article discusses some of the most common types of chemical reactions that are likely to be included in a good chemistry set.

Chemical Makeup

All chemicals are made up of atoms, ions or molecules. Atoms are the smallest division of an element, including one set of protons, neutrons and electrons. The simplest atom on earth is hydrogen, which contains exactly one proton, one neutron and one electron. Electrons are charged particles that revolve around the protons and neutrons (which make up the nucleus) of an atom in a similar fashion to the planets revolving around the sun. Ions are charged atoms that form when atoms gain or lose electrons. Molecules form when two or more atoms join together and either exchange or share electrons.

Why Chemical Reactions Occur

As mentioned above, all atoms have electrons revolving around nuclei made up of protons and neutrons. Because the electrons are on the outside of the atoms or ions, they are the components that react with each other. An atom can have several distinct orbits, and there is a maximum number of electrons on each orbit. The first orbit, for example, can hold only two electrons.

Actually, the first orbit wants to have two electrons, which is why hydrogen, with only a single electron, is so highly reactive. Hydrogen atoms borrow an electron from neighboring atoms, which allows the hydrogen to reach a more stable state. The next two orbits on an atom can hold up to eight electrons each, so an atom with a partially full orbit will seek out electrons to fill the outermost orbit or it will transfer remaining electrons on a partially full orbit to other atoms, always with the ultimate result of reaching a stable state with full orbits.

Basic Types of Reactions

Synthesis
(X + Y ⇒ XY)

Synthesis occurs when two or more chemicals combine to form a new chemical.

Decomposition
(XY ⇒ X + Y)

Decomposition is the reverse of synthesis. In a decomposition reaction, one chemical breaks down into two or more components. A decomposition reaction is not the same as decomposition of living materials.

Replacement Reaction
[XY + A ⇒ X + YA (Single Replacement) or XY + AB → XB + YA (Double Replacement)]

A replacement reaction occurs when two or more chemicals exchange ions. In a single replacement reaction, a single ion migrates from one molecule to another. In a double replacement reaction, two molecules exchange ions to form two new molecules.

Acid-Base Reaction
(Acid + Base ⇒ Salt + Water)

Acid-base reactions are actually very simple because all acids and all bases are similarly built. All acids contain hydrogen ions (which, as discussed above, are very reactive), and all bases contain hydroxides (chemical symbol OH-) made up of one oxygen ion and one hydrogen ion. The hydrogen in the acid joins with the hydroxide in the base to form water, and the remaining portions of each molecule join to form a salt. All acid-base reactions result in salt and water. One of the most common household applications of this principle is table salt, or NaCl, which is formed when hydrochloric acid reacts with sodium hydroxide, resulting in sodium chloride and water.

This article does not incorporate all types of chemical reactions, but it does give an overview of some of the basic reactions you will observe when using a chemistry set. If you build your chemistry education on a solid understanding of how atoms are structured and why they react with one another, it is much easier to understand the more complex principles taught in higher-level science classes.

Many of the chemistry sets in our lineup contain experiments in these basic types of chemical reaction, as well as demonstrations designed to reveal the structure and properties of matter. Chemistry sets are great tools to spark your child’s interest in science and to assure that he/she learns the basics well enough to progress to more complex lessons.

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