7. Lewis structures of CO₂, carbon dioxide.

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1. Compute the number of electrons (N_T) in the valence shell for all the atoms in the molecule.

	Correct. C: 4; O: 6. Total: 16 electrons
	Wrong. Check the valence electrons of C and O.
	Wrong. Check the valence electrons of C and O.

2. Select the central atom :

	Correct. The central atom is the less electronegative. In this case C
	Wrong. The central atom is the less electronegative.

3. Compute the number of electrons used in single bonds:

	Wrong. Two C-O bonds require four electrons.
	Correct. There are two C-O bonds that require 4 electrons

4. To complete the octeto in the terminal atoms are required (total electrones).

	Wrong. In this case each terminal O atom will only complete 6 electrones.
	Wrong. In this case each terminal O atom will only complete 7 electrones.
	Correct. In this case each O atom will complete 8 electrons. Total 12

5. ¿ How many electrons needs the central atom to complete the octeto?

	Wrong. The central atom shares 4 electrons with the two O atoms. Two electrons more will only complete 6 electrons around the C atom.
	Wrong. The central atom shares 4 electrons with the two O atoms. Three electrons more will only complete 7 electrons around the C atom.
	Correct The central atom shares 4 electrons with the two O atoms. Four electrons more will complete the 8 electrons required around the C atom. However there are no more electrons available. ¿How to we explain this problem?

5b. ¿How do we explain this situation?

	Wrong. Carbon atoms generally complete the octeto.
	Correct. The central atom shares two additional electrons with each of the oxygen atoms.

6. ¿How is the shape of this molecule? Structures

	Correct. This molecule is of AX2 type and adopts a linear shape. Linear
	Wrong his molecule is of AX2 type and cannot adopt and angular shape.

7. ¿How is the polarity of this molecule? Polarity, Electronegatividad

	Wrong. This molecule has two polar bonds. The dipolar moments cancel each other.
	Correct This molecule has two polar bonds. The dipolar moments cancel each other. Dipols

8. In this molecule the central atom shares four electrons with each terminal atom. The C-O bonds are double bonds, one sigma and one pi bond. ¿What orbitals uses the C atom to form the sigma bond? orbitals

	Correct. The central carbon atom forms two sigma bonds using two "sp" orbitals . The two "sp" orbitales look similar to one "p" but they overlap in both sides with "p" orbitals of O atoms. del oxígeno.
	Wrong For sigma overlap C-O two orbitals are required.

Finally pi orbitales pi orbitals complete the orbital overlap between C and O. The combination of a sigma and a pi orbital form the C=O double bond.