Quote from: Avni on January 23, 2024, 11:47:26 PMPhysical Science – Short Answer In high-density polyethylene, or HDPE, each carbon atom
bonds to how many other carbon atoms?
ANSWER: 2

Polyethylene is a polymer of  ethylene and in this CH2=CH2 molecules are combining with themself to form polyethylene by breaking of pi bonds.
nCH2=CH2 ----> -CH2-CH2-CH2-CH2-CH2- or (-CH2-CH2-)n
Repeating unit is CH2-CH2 in which each carbon is bonded with two more carbons.

Do the pi bonds break during the polymerization process? And after you break the bonds, you are left with Sigma bonds, right? Because the CH2-CH2 has only one bond between each other left after polymerization?

During addition polymerization pi bonds are broken and monomers ( smallest repeating molecule )are simply added together.
However in condensation polymerization small molecules like water molecule is eliminated on addition of monomers.

Ok, thank you!