Question 6.14: Draw the Lewis structures for carbon dioxide, CO2.
Draw the Lewis structures for carbon dioxide, CO_{2} .
STEP 1 Determine the arrangement of atoms. In CO_{2} , the central atom is C because there is only one C atom.
O C OSTEP 2 Determine the total number of valence electrons. We use the group numbers to determine the number of valence electrons for each of the atoms in the molecule.
STEP 3 Attach each bonded atom to the central atom with a pair of electrons.
O_{\bullet }^{\bullet }C_{\bullet }^{\bullet }O or O — C — OWe use four valence electrons to attach the central C atom to two O atoms, which leaves 12 valence electrons.
STEP 4 Use the remaining electrons to complete octets, using multiple bonds if needed. The 12 remaining electrons are placed as six lone pairs of electrons on the outside O atoms. However, this does not complete the octet of the C atom.
{}_{\bullet }^{\bullet } \overset{\bullet \bullet }{\underset{\bullet \bullet }{O_{\bullet }^{\bullet }}} C_{\bullet }^{\bullet } \overset{\bullet \bullet }{\underset{\bullet \bullet }{O_{\bullet }^{\bullet }}} \text{or} {}_{\bullet }^{\bullet } \overset{\bullet \bullet }{\underset{\bullet \bullet }{O}} — C — \overset{\bullet \bullet }{\underset{\bullet \bullet }{O_{\bullet }^{\bullet }}}To obtain an octet, the C atom must share pairs of electrons from each of the O atoms. When two bonding pairs occur between atoms, it is known as a double bond.
| ANALYZE THE PROBLEM | Given | Need | Connect |
| CO_{2} | Lewis structure | total valence electrons |
| Element | Group | Atoms | Valence Electrons | Total |
| C | 4A (14) | 1 C \times | 4 e^{-} = | 4 e^{-} |
| O | 6A (16) | 2 O \times | 6 e^{-} = | 12 e^{-} |
| Total valence electrons for CO_{2} = | 16 e^{-} | |||