Question

of covalent bonds an atom can form usually equals the number of electrons needed to fill its valence (outermost) shell. 8. why does the following structure fail to make sense chemically? (hint: remember how many covalent bonds each atom needs to reach stability). h-c=c-o

Explanation:

Step1: Recall bonding rules

Carbon (C) needs 4 bonds, Hydrogen (H) needs 1, Oxygen (O) needs 2 to be stable.

Step2: Analyze each atom

• Left C: bonded to H (1) and double - bonded to right C (2), total 3 bonds (needs 4).
• Right C: double - bonded to left C (2), bonded to O (1), total 3 bonds (needs 4).
• O: bonded to right C (1), needs 1 more (needs 2 total).

Step3: Identify the issue

Oxygen has only 1 bond (needs 2), and each carbon has 3 bonds (need 4). The structure doesn't satisfy the octet (or duet for H) rule for covalent bonding stability.

Answer:

The structure \( \text{H}-\text{C}=\text{C}-\text{O} \) fails chemically because:

• Carbon atoms: Each C needs 4 covalent bonds for stability. The left C has 1 (from H) + 2 (from \( \text{C}=\text{C} \)) = 3 bonds. The right C has 2 (from \( \text{C}=\text{C} \)) + 1 (from \( \text{C}-\text{O} \)) = 3 bonds (both lack 1 bond).
• Oxygen atom: O needs 2 covalent bonds (to fill its valence shell). Here, O has only 1 bond (from \( \text{C}-\text{O} \)) (lacks 1 bond).

Thus, the atoms do not satisfy the covalent bonding requirements (octet/duet rule) for stability.