What is the maximum number of double bonds a carbon atom can make?
Well, carbon has $4$ valence electrons so... it needs $4$ more to fulfill the octet rule right?
If a double bond yields $4$ electrons, does it mean that the carbon atom can make only one double bond?
OR does it mean it can create up to TWO double bonds (because they would yield $8$ electrons which fulfill the octet rule)?
What about Calcium? I ask because Calcium doesn't follow the Octet rule: it only wants to have 4 electrons, so...