Question

Draw an electron-dot structure for \(\mathrm{N}_{2}\), and explain why this molecule is so unreactive.

Short answer

The electron-dot structure for \\(\text{N}_2\\) is \\(.: \text{N} \equiv \text{N} :.\\), and it is unreactive due to its strong triple bond.

Step-by-step solution

Determine total valence electrons

Nitrogen (N) is in group 15 of the periodic table and has 5 valence electrons. Since the molecule is \(\text{N}_2\), we multiply this by 2, giving us a total of 10 valence electrons to distribute.

Draw a skeleton structure

For the diatomic nitrogen molecule \(\text{N}_2\), the two nitrogen atoms will be connected by a single bond. Draw this initial N-N connection.

Complete the octets

Add electrons to the N-N bond to complete the octet around each nitrogen. Start by adding a single pair (single bond), and supplement additional pairs of electrons around the atoms as needed.

Form triple bonds

Single bonds leave electrons unpaired, so increase the bond order by transforming lone pairs into triple bonds. This gives each nitrogen atom a filled octet (8 electrons), resulting in three shared pairs of electrons (6 electrons total in bonds). The structure now has a triple bond: \(: \text{N} \equiv \text{N} :.\).

Understand molecular stability

The presence of the strong triple bond (comprising one sigma and two pi bonds) between the nitrogen atoms gives \(\text{N}_2\) significant bond energy, making it less reactive and more stable.

Key concepts

Valence Electrons

In chemistry, valence electrons play a crucial role in the formation of chemical bonds. These are the electrons present in the outermost shell of an atom. For nitrogen, which is in group 15 of the periodic table, there are 5 valence electrons. This means each nitrogen atom has five electrons that can be involved in bonding with other atoms.
In a nitrogen molecule ( _2 d), we consider the valence electrons from both nitrogen atoms. By doubling the 5 valence electrons, we identify a total of 10 electrons to arrange during bond formation. Understanding the role of valence electrons helps explain how atoms achieve stability by completing their outer electron shells during bonding.

• Valence electrons determine an atom's bonding capacity.
• Nitrogen has 5 valence electrons.
• In _2 d, the total number of valence electrons is 10.

Nitrogen Molecule

A nitrogen molecule _2 d consists of two nitrogen atoms. Each atom shares electrons to fulfill its octet requirement. When visualizing or drawing its structure, we start by placing the two nitrogen atoms side by side. Initially, we might depict them connected by a single bond.
However, to satisfy the octet rule, where every atom needs eight electrons in its outer shell, adjustments are necessary. As part of reaching stable configuration, nitrogen atoms will share more electrons, eventually forming a triple bond. This allows both nitrogen atoms to have eight electrons in their valence shells, ensuring stability. The nitrogen molecule is a great example to illustrate how diatomic molecules behave and bond.

• Nitrogen typically appears as a diatomic molecule ( _2 d).
• Its structure must satisfy the octet rule.

Triple Bond

A triple bond in chemistry refers to a scenario where two atoms share three pairs of electrons. In the nitrogen molecule _2 d, each nitrogen atom shares three pairs of electrons with the other. These three shared pairs constitute six shared electrons in total, creating a strong and stable triple bond.
Triple bonds are characterized by one sigma bond and two pi bonds. In a sigma bond, electron density is located along the line connecting the two nuclei, whereas pi bonds have electron density spread above and below this line. Such bonds require more energy to break, thus providing significant molecular stability.

• Triple bonds involve three pairs of shared electrons.
• They consist of one sigma bond and two pi bonds.
• Triple bonds impart significant strength and stability to the molecule.

Molecular Stability

Molecular stability pertains to how resistant a molecule is to chemical reactions and external changes. The nitrogen molecule _2 d is notably stable because of its strong triple bond, which comprises a sigma bond and two pi bonds. This robust bonding structure endows _2 d with high bond energy, making it less likely to participate in chemical reactions.
A high bond energy implies that a lot of energy is required to break the bonds within the molecule. As a result, nitrogen gas ( _2 d), which makes up over 78% of Earth's atmosphere, remains generally unreactive under standard conditions. The stability also makes nitrogen beneficial in various industrial applications where inert environments are necessary.

• Molecular stability is linked to bond strength and energy.
• Nitrogen's triple bond confers exceptional stability.
• Stable molecules like _2 d are less reactive.