N₂ has a triple bond, O₂ has a double bond, and F₂ has a single bond. Moving from F₂ to N₂, which trend correctly describes bond length and bond energy?
ABond length increases and bond energy increases
BBond length decreases and bond energy decreases
CBond length decreases and bond energy increases
DBond length increases and bond energy decreases
Higher bond order (more shared electron pairs) pulls the nuclei closer together, shortening the bond, while simultaneously making the bond harder to break, increasing the bond energy. N₂ (triple bond) has the shortest and strongest bond; F₂ (single bond) has the longest and weakest. Bond length and bond energy move in opposite directions as bond order increases.
Question 2 True / False
Most covalent bonds involve equal sharing of electrons between the two bonded atoms.
TTrue
FFalse
Answer: False
Equal sharing only occurs in homonuclear bonds (e.g., H₂, Cl₂) where both atoms have identical electronegativity. In heteronuclear bonds (e.g., H₂O, HCl), the more electronegative atom pulls the shared electrons closer, creating an unequal (polar) distribution. Covalent bonding exists on a spectrum from purely covalent to polar covalent to ionic, based on the electronegativity difference between the atoms.
Question 3 Short Answer
Nitrogen forms a triple bond in N₂ rather than a single or double bond. Using the octet rule and the concept of bond order, explain why.
Think about your answer, then reveal below.
Model answer: Each nitrogen atom has 5 valence electrons. To satisfy the octet rule (8 electrons in the valence shell), each nitrogen needs 3 more electrons. By sharing 3 pairs (a triple bond), both nitrogen atoms achieve a full octet. A single or double bond would leave each nitrogen atom with unfilled valence electrons and a less stable configuration.
The number of bonds an atom tends to form is related to how many electrons it needs to reach an octet. Nitrogen (Group 15, 5 valence electrons) needs 3 more, so it forms 3 bonds. The triple bond in N₂ also results in an exceptionally short, strong bond (945 kJ/mol), which is why N₂ is chemically inert under ordinary conditions.