quimica das coisas


It may seem like an ordinary laptop computer and chemistry live worlds apart, but in fact the very existence of laptops is only possible thanks to major developments in chemistry.

There is chemistry in many components of a computer, but today we’ll talk about the chemistry hidden in something very visible: the flat LCD monitors, to which the laptops owe their shape.

LCD stands for Liquid Crystal Display.

But what are liquid crystals? The name itself seems a contradiction! Usually we consider crystals a solid things (such as a diamond!) and not a liquid

In crystalline substances, the particles have fixed positions and orientations, like soldiers on parade, and that’s why we classify them as solids. On the other hand, liquids are like a disorderly mob, and the particles easily change position and orientation.

But there are substances that have both the structure of a liquid and a solid, such as liquid crystals.

I will explain better: if we throw some coins into a glass box and look at them from above, we see a disorganized distribution of coins, such as molecules in a liquid. But if we look from the side, we see that the coins are arranged preferably horizontally in successive layers, as organized as the molecules in a solid.

This physical duality gives liquid crystals special optical properties. By choosing the appropriate molecules, we can build an LCD: the very precise alignment of the molecules we get by applying an electric current enables the production of images on a flat surface by the passage of light through the liquid crystals and colour filters.

This way, advances in chemistry (and technology) allowed the construction of the indispensible flat screens of our laptops, tablets and palmtops.

To know more about the chemistry of laptops, visit our website quimicadascoisas.org or look for us on Facebook.