CHE1502
GENERAL
CHEMISTRY IB
, KEY TO ASSIGNMENT 01
1. Correct Answer: (4) In a carbon atom, the 2s an 2p orbitals are equal in energy
The above statement is incorrect with regards to the properties of the carbon atom. The 2p orbitals
are slightly higher in energy than the 2s because the average location of the electron in a 2p
orbital is farther from the nucleus. All the other options are correct.
2. Correct Answer: (3) Most of the electron density in a π molecular orbital is centered
above and below the internuclear axis. All the other options are incorrect
(1) When two atoms are connected by a double bond, both of these bonds are π
bonds. This statement is incorrect, as all single bonds in organic compounds are sigma
bonds and every double or triple bonds contain one sigma bonds. So a double bonded
structure contains a sigma and a pi bond.
(3) π molecular orbitals are cylindrically symmetric. This statement is incorrect since sigma
bonds are cylindrically symmetrical whilst pi bonds are not as they involve parallel
overlaps rather than the linear overlap of sigma bonds.
(4) Both statements (1) and (3) are correct. As explained above, both statements are
incorrect
3. Correct Answer: (4)
O
C H
H O
The above structure is the correct Lewis structure for the molecule with molecular formula of
CH2O2.
2
GENERAL
CHEMISTRY IB
, KEY TO ASSIGNMENT 01
1. Correct Answer: (4) In a carbon atom, the 2s an 2p orbitals are equal in energy
The above statement is incorrect with regards to the properties of the carbon atom. The 2p orbitals
are slightly higher in energy than the 2s because the average location of the electron in a 2p
orbital is farther from the nucleus. All the other options are correct.
2. Correct Answer: (3) Most of the electron density in a π molecular orbital is centered
above and below the internuclear axis. All the other options are incorrect
(1) When two atoms are connected by a double bond, both of these bonds are π
bonds. This statement is incorrect, as all single bonds in organic compounds are sigma
bonds and every double or triple bonds contain one sigma bonds. So a double bonded
structure contains a sigma and a pi bond.
(3) π molecular orbitals are cylindrically symmetric. This statement is incorrect since sigma
bonds are cylindrically symmetrical whilst pi bonds are not as they involve parallel
overlaps rather than the linear overlap of sigma bonds.
(4) Both statements (1) and (3) are correct. As explained above, both statements are
incorrect
3. Correct Answer: (4)
O
C H
H O
The above structure is the correct Lewis structure for the molecule with molecular formula of
CH2O2.
2
