Water (H20) – one of the most valuable resources on our planet.

Amazing scientific facts about water:

  • It is transparent to sunlight
  • Has high density compared to air
  • Conducts electricity
  • It has low viscosity – it flows easily.

Water is simply amazing, unusual and because we are so familiar with it, we take it for granted.

How much fun is water?

We swim in it, float on it, dive underneath the surface of it, surf on top of it, drink and we are made of it.

I’m a bit of science geek and love delving a little deeper. Carry on reading if you want to understand the fascinating science behind water.

What is water?

A transparent, odourless, tasteless liquid, a compound of hydrogen and oxygen, freezing at 32°F or 0°C and boiling at 212°F or 100°C, that in more or less impure state constitutes rain, oceans, lakes, rivers etc. It contains 11.188% hydrogen and 88.812% oxygen by weight.

Water is essential for life as we know it. Organisms themselves are mostly made of it, the human body being about 60% water. It has many chemical and physical properties making it rather strange also.

Why is water sticky?

Water molecules have slightly negatively and positively charged regions due to the varied distribution of electrons between the oxygen and hydrogen atoms. This feature means water molecules are attracted to each other by their negative and positive ends. The forces that draw molecules together are called hydrogen bonds and it’s these that make water such a unique, special compound.

The hydrogen bonds that exist in the molecule ensure water stays a liquid at room temperature. Most other compounds this small are gases.

Why do substances dissolve in water?

Water is often called the universal solvent because so many things can be dissolved in it. Substances with an electrostatic charge are attracted to water’s charges and are called hydrophilic. Substances like oil are called hydrophobic, they don’t dissolve in water because they’re molecules have no charge.

Why does water form a skin on the surface?

This is because of the attraction between its molecules. The attraction between water molecules is far greater than their attraction to molecules in the air. At the water surface where it meets the air, the water molecules form hydrogen bonds with other water molecules not with the air. These hydrogen bonds produce a special force called surface tension. The surface then contracts creating a skin.

Why does ice float on water?

This is because density with water varies when the temperature cools. 4°C is when water is at its most dense. The temperature of water at the bottom on an ocean will be a relatively constant 4°C. As water freezes the hydrogen bonds form a lattice effect holding each molecule slightly further apart. That’s why water expands when you freeze it and explains why ice floats. It’s less dense.

Water and temperature

It takes a lot of heat or energy to raise the temperature of water. It also has to lose a lot of energy for the temperature to lower. Water has a high specific heat capacity. Lots of energy is needed to make water evaporate.