Video Transcript
Which of the following chemical
formulas represents a compound? (A) P4, (B) H2, (C) O3, (D) MgCl2,
or (E) Cl2.
Compounds are substances that
contain the atoms of two or more different elements, where an atom is defined as the
smallest unit of ordinary matter that forms a chemical element. And an element is a substance that
consists of one type of atom.
One molecule of P4,
tetraphosphorus, contains four atoms of the same element, phosphorus. As a compound contains two or more
different elements, P4 cannot be a compound. Therefore, answer choice (A), P4,
is not the answer to this question.
The case is the same for hydrogen,
ozone, and chlorine molecules. All of these molecules contain one
type of element hence are not compounds. Therefore, answer choices (B), (C),
and (E) are also incorrect.
Magnesium chloride, MgCl2, however,
contains two different elements: magnesium and chlorine. Note that magnesium chloride
actually has a large layered structure. So magnesium chloride is a
compound. Specifically, it’s known as a salt
compound. As magnesium chloride is the only
listed substance which contains more than one type of element, the chemical formula
which represents a compound is (D), MgCl2.
