Electron Dot Structure of Carbon Dioxide (CO₂)

Before drawing, identify the outermost electrons:

• Carbon (C): Atomic number 6. Electronic configuration is (2, 4). It has 4 valence electrons and urgently needs 4 more to reach an octet (8).
• Oxygen (O): Atomic number 8. Electronic configuration is (2, 6). It has 6 valence electrons and needs 2 more to reach an octet.
• The formula is CO₂, so we have 1 Carbon and 2 Oxygens.

Step 1: The Central Atom Place the Carbon atom exactly in the center. Draw its 4 valence electrons as dots (place two dots on the left side, and two dots on the right side).

Step 2: Place the Oxygens Place one Oxygen atom on the left of the Carbon, and the second Oxygen on the right.

Step 3: The Sharing (Double Bonds)

• The left Oxygen needs 2 electrons. So, it shares 2 of its electrons with the 2 electrons on the left side of the Carbon. This creates a group of 4 shared electrons (a Double Bond: O=C).
• The right Oxygen also needs 2 electrons. It shares 2 of its electrons with the remaining 2 electrons on the right side of the Carbon. This creates another group of 4 shared electrons (a second Double Bond: C=O).

Step 4: The Lone Pairs (Crucial Step)

• Each Oxygen originally had 6 electrons and only shared 2.
• Therefore, you MUST draw the remaining 4 unshared electrons (as two pairs) on the outside of each Oxygen atom. These are called 'Lone Pairs'.
• The Carbon atom shared all 4 of its electrons, so it has zero lone pairs.

The final structure is linear and symmetrical: :O::C::O: (or O=C=O). If you draw a circle around the Carbon, it contains exactly 8 shared electrons. If you draw a circle around each Oxygen, they also contain exactly 8 electrons.