Question Video: Describing What a Chemical Compound Is Chemistry

Fill in the blank: A chemical compound is made up of _. [A] a single element only [B] fewer than three elements [C] more than two atoms [D] only two atoms [E] two or more different elements

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Video Transcript

Fill in the blank. A chemical compound is made up of blank. (A) A single element only. (B) Fewer than three elements. (C) More than two atoms. (D) Only two atoms. Or (E) two or more different elements.

To determine what a chemical compound is made up of, let’s take a look at a common compound. Water is an example of a compound. It has the chemical formula H2O. Capital H and capital O are the chemical symbols of the elements hydrogen and oxygen. Already, we can see that this compound contains more than two elements. This means that answer choice (A) cannot be the correct answer to this question.

Returning to the chemical formula of water, we see a subscript two after the chemical symbol for hydrogen. This subscript indicates the number of atoms of hydrogen that make up one molecule of water. No subscript appears after the chemical symbol of oxygen. This means that a molecule of water only contains one atom of oxygen. So one molecule of water contains a total of three atoms: two atoms of hydrogen and one atom of oxygen. As water is a chemical compound which contains three total atoms, we can eliminate answer choice (D).

Water does contain fewer than three elements, more than two atoms, and is composed of two or more different elements. So let’s look at another chemical compound to narrow down the answer choices. Sugar is another common chemical compound. Its chemical formula is C12H22O11. So sugar contains the elements hydrogen and oxygen as well as the element carbon. As sugar is a chemical compound that contains three elements, answer choice (B) cannot be the correct answer to this question. Sugar does contain more than two atoms and is composed of two or more different elements.

To determine which of the remaining answer choices is correct, let’s take a look at a substance that is not a chemical compound. Ozone, found in Earth’s stratosphere, has the chemical formula O3. As ozone is only composed of a single element, it is not an example of a compound. But it is composed of three atoms. This tells us that answer choice (C) is not an accurate enough description of a compound, as there are some species that contain more than two atoms that are not classified as a chemical compound.

This leaves us with answer choice (E). To be certain that we arrived at the correct conclusion, let’s look at the definition of a chemical compound. A chemical compound is defined as a species composed of atoms of two or more different elements that are chemically combined. The definition supports our conclusion that answer choice (E) is the correct answer. So we should fill in the blank with answer choice (E) two or more different elements.

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