In the peak of summer as we all sip a glass of cold water, let us all talk about water. All of you know water is chemically represented as H2O, as it consists of one atom of oxygen bound to two atoms of hydrogen. The hydrogen atoms are attached to the oxygen atom, resulting in a water molecule having a positive charge on the side where the hydrogen atoms are attached and a negative charge where the oxygen atom is. The water molecules tend to attract each other, where the positive charge hydrogen atoms attract the negatively charged oxygen of another water molecule.

We all know water exists in several forms such as solid, liquid and ice. Water boils at 100  C and freezes at 32  F, right? Am I correct? Let us look at some of the chemistry behind forms of water. Water in the solid form of ice, is less dense than the liquid form, so it floats. The density of ice is lesser, due to the regular arrangement of water molecules via hydrogen bonds. Every hydrogen atom is involved in hydrogen bond. So what happens to the density when it is in gas form? When something is cold it is supposed to shrink due to less molecular vibrations. However, water expands when frozen resulting in increase in volume, due to its shape. As a resultant of the molecular interactions, when water freezes, it releases energy due to strong chemical bonds it makes. As ice melts to water, due to change in temperature, the uniform three-dimensional tetrahedral organization of the solid breaks down as thermal motions disrupt, distort, and occasionally break hydrogen bonds.

Some of the questions that bother little scientists in you are, why does water not fall off into the space when earth rotates and how does water make a rainbow and complicated questions like does water exists on other planets?

As we keep learning our physical sciences well, we learn of different forces, density and pressure. Another interesting fact worth mentioning is that hot water freezes faster than cold water. Can anyone guess why? More questions...Can you explain why in cold weather we see water droplets on wind shield of a car and also on water bottles in refrigerator? Since there is enough oxygen in water why do aquatic beings come to the surface to breathe in oxygen? As you prepare to beat the summer by swimming, talk to your teacher about fun experiments with water. Study well, before water in the form of rain starts to pour.

Contributed by Dr. Ramars Amanchy CSIR-IICT.