Question

decide whether these proposed lewis structures are reasonable. proposed lewis structure is the proposed lewis structure reasonable? yes. no, it has the wrong number of valence electrons. the correct number is: no, it has the right number of valence electrons but doesnt satisfy the octet rule. the symbols of the problem atoms are: yes. no, it has the wrong number of valence electrons. the correct number is: no, it has the right number of valence electrons but doesnt satisfy the octet rule. the symbols of the problem atoms are: yes. no, it has the wrong number of valence electrons. the correct number is: no, it has the right number of valence electrons but doesnt satisfy the octet rule. the symbols of the problem atoms are: * if two or more atoms of the same element dont satisfy the octet rule, just enter the chemical symbol as many times as necessary. for example, if two oxygen atoms dont satisfy the octet rule, enter \o,o\.

Explanation:

Step1: Calculate valence electrons for \(HCN\)

• \(H\) has \(1\) valence electron, \(C\) has \(4\), \(N\) has \(5\). Total valence electrons: \(1 + 4+5=10\).
• In the proposed structure \(H - C = N\), bonds contribute \(2\) electrons per bond (\(2\) bonds: \(2\times2 = 4\) electrons from bonds). Lone - pairs: \(C\) has \(0\) lone - pairs (in this structure as drawn, but actually wrong), \(N\) has \(2\) lone - pairs (\(2\times2=4\) electrons). Total electrons shown: \(4 + 4=8\). But also, we check octet. \(C\) has \(6\) electrons (from \(3\) bonds: \(H - C\) is \(1\) bond (\(2\) electrons) and \(C = N\) is \(2\) bonds (\(4\) electrons), total \(6\) for \(C\)), \(N\) has \(8\) electrons (\(2\) bonds (\(4\) electrons) and \(2\) lone - pairs (\(4\) electrons)). So, wrong number of valence electrons. The correct number is \(10\).

Step2: Calculate valence electrons for \([H - O:]^{-}\)

• \(H\) has \(1\) valence electron, \(O\) has \(6\), and there is an extra electron (due to the negative charge). Total valence electrons: \(1+6 + 1=8\).
• In the structure \([H - O:]^{-}\), the \(H - O\) bond has \(2\) electrons. \(O\) has \(3\) lone - pairs (\(3\times2 = 6\) electrons). Total electrons shown: \(2+6=8\). Check octet: \(H\) follows its duet rule (\(2\) electrons), \(O\) has \(8\) electrons (\(2\) from the bond and \(6\) from lone - pairs). So, the structure is reasonable.

Step3: Calculate valence electrons for \(O - C - O\)

• \(O\) has \(6\) valence electrons each, \(C\) has \(4\). Total valence electrons: \(6\times2+4 = 16\).
• In the structure \(O - C - O\), each \(O - C\) bond has \(2\) electrons (\(2\times2=4\) electrons from bonds). Each \(O\) has \(3\) lone - pairs (\(2\times3\times2 = 12\) electrons from lone - pairs on \(O\)s), \(C\) has \(2\) lone - pairs (\(2\times2 = 4\) electrons). Total electrons shown: \(4+12 + 4=20\). Also, check octet: \(C\) has \(6\) electrons (from \(2\) bonds (\(4\) electrons) and \(1\) lone - pair (\(2\) electrons)), each \(O\) has \(8\) electrons (\(1\) bond (\(2\) electrons) and \(3\) lone - pairs (\(6\) electrons)). Wrong number of valence electrons. The correct number is \(16\).

Answer:

• For \(H - C = N\): No, it has the wrong number of valence electrons. The correct number is \(10\).
• For \([H - O:]^{-}\): Yes.
• For \(O - C - O\): No, it has the wrong number of valence electrons. The correct number is \(16\).