Chemistry

Typically, when something is cold, it shrinks. That’s because temperature describes atomic vibration — the more vibration, the more space it takes, hence expansion. Water is an exception. Even though it vibrates less when it’s frozen, the ice occupies more volume. That’s due to the strange shape of the water molecule.

A metal is an element that readily forms positive ions (cations) and has metallic bonds. These elements have electrons that are loosely held to the atoms, and will readily transfer them. This is why metals are great electrical and thermal conductors — because the electrons move energy.

When you step inside a bathtub, the water level will immediately go up, per Achimedes’ law. But when you add a volume of sodium chloride (salt) to a volume of water, the overall volume actually decreases by up to 2%. The net reduction in observed volume is due to solvent molecules which become more ordered in the vicinity of dissolved ions.

Glass is an amorphous solid—a state somewhere between those two states of matter. And yet glass's liquidlike properties are not enough to explain the thicker-bottomed windows, because glass atoms move too slowly for changes to be visible.

Soap is a mixture of amphipathic molecules, which have both a hydrophobic chain and a hydrophilic head. In water, these molecules such as fatty acid carboxylates, are arranged forming micelles. Micelles arrange the hydrophobic chains towards the center, and the hydrophilic heads towards the outside (water).