Water is a vital substance without which life cannot exist. It covers around 70% of the Earth's surface and is present in all living things.
A water molecule consists of two hydrogen atoms bonded to an oxygen atom (H2O). The structure of a water molecule gives it some unique properties that are essential for life on Earth.
Water molecules are attracted to each other (hydrogen bonding) and this gives water its liquid form at room temperature. When water freezes, the hydrogen bonds between molecules become stronger, causing ice to be less dense than liquid water and float on top of it. This is why lakes and rivers freeze from the top down.
Water has a high specific heat capacity, meaning it can absorb a lot of heat before its temperature rises. This makes it ideal for regulating body temperature as it can help us stay cool in hot weather and protect us from cold temperatures. Water also has a high latent heat of vaporization, meaning it takes a lot of energy to turn it into steam/vapor. This property helps keep our bodies cool as sweat evaporates from our skin.
Water is also an excellent solvent, able to dissolve many different substances. This allows nutrients and minerals to be transported around the body and helps to moderate pH levels in blood and other tissues