Question Video: Identifying the Formula That Shows a Molecule of Oxygen | Nagwa Question Video: Identifying the Formula That Shows a Molecule of Oxygen | Nagwa

# Question Video: Identifying the Formula That Shows a Molecule of Oxygen Science

A molecule of oxygen (O₂) can be represented in different ways to show the double covalent bond present between the two oxygen atoms. Which of the following formulas correctly shows a molecule of oxygen? [A] Formula A [B] Formula B [C] Formula C [D] Formula D [E] Formula E

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### Video Transcript

A molecule of oxygen, O2, can be represented in different ways to show the double covalent bond present between the two oxygen atoms. Which of the following formulas correctly shows a molecule of oxygen? We have been given a list of options from (A) to (E).

To understand the bonding in oxygen, let’s first find oxygen in the periodic table. The proton number or atomic number is eight. This is equivalent to the number of protons, and in a neutral atom, the number of electrons. Two electrons fill the first shell. The remaining six electrons fill the second shell.

The question tells us that there are two atoms of oxygen in an oxygen molecule. We can represent these two atoms with dot-and-cross diagrams. In this diagram, the electrons in one oxygen atom are represented by dots and the electrons in the other oxygen atom are represented by crosses.

Before we understand how the atoms combine, we need to recall the octet rule. The octet rule states that atoms tend to create chemical bonds to have eight valence shell electrons and the same electron configuration as the nearest noble gas.

Both atoms currently have six outer-shell electrons. And they should have eight once bonded. To allow each atom to have eight electrons in its outer shell, oxygen forms a double covalent bond, as stated in the question, where covalent bonds are chemical bonds that are formed when two nonmetal atoms share one or more pairs of electrons. A single covalent bond is formed of a single electron pair, whereas a double covalent bond is formed of two electron pairs. This is the type of bond in an oxygen molecule.

The dot-and-cross diagram allows us to see that each atom donates two electrons to form this double bond. This diagram depicts the double covalent bond present between two oxygen atoms. But we can represent it in another way. Each bond formed from two electrons can be represented by a solid line between the two oxygen atoms. Since oxygen has a double covalent bond formed of four shared electrons, it can be represented by two solid lines. Thus, the formula which correctly shows a molecule of oxygen can be found in answer choice (A).