In a candle, when wax is molten and cools after. It sticks to the glass surrounding it, why does this happen?
The molecules that make up glass are populated with oxygen and hydrogen atoms and those of the wax are populated with hydrogen atoms. Weak hydrogen bonding is therefore possible between the hydrogens in glass and those in the wax when they meet; in essence, the wax looks a little like glass to the glass molecules and the glass looks a little like wax to the wax molecules, and you get a mild attractive force between them. That bonding is relatively weak, so it is possible to break it by prying the wax loose with a butter knife.