WHY IS GLASS TRANSPARENT?

Hello everyone! With today’s post  I’m going to start  a series with the answers  to many common questions from everyday life which may seem predictable or obvious but are not .

 The first question I’d like to answer is “Why is glass transparent?” Have you ever wondered how something like glass can be so invisible?

To answer this we have to understand the nature of glass and its origins . It all begins in the Earth's  crust where the two most common elements silicon and oxygen combine forming crystals of silicon dioxide also known as quartz. We find quartz especially in sand and it is the main component of glass; but, because of the edge of the grains and smaller defects in the crystal structure,  its untreated form can't let the light pass trough. However, if we heat it up, the energy breaks the atomic bonds of its atoms becoming a flowing liquid, just like melting ice. When it cools down it doesn't reshape as a crystal solid,  but as a solid with a different shape and a uniform atom structure allowing light to strike it without being scattered in different directions.

But why do the other solids absorb most of the rays ? We  can find the answer we need in the subatomic structure  of the silicon dioxide. Every atom has different components, a nucleus of protons and neutrons and, externally, there are electrons  orbiting around it. Have you ever heard the phrase we are made up of void for 99.99 % ? Well,  it's true . Try to imagine a football stadium: the nucleus is a pea in the centre of the field and the electrons are smaller peas in the outermost seats.

So the question now is “Why  isn’t every object  transparent ?” around the nucleus there are different levels of energy around which the electrons orbit. If the electrons receive some energy (in this case light radiation) they can jump to an outer and better level, the further away  it is  the more energy it takes , and in the glass they are very far from each other so the energy of the light radiation isn't absorbed to move the electrons to another level and it passes trough. For example,  ultraviolet radiation, which is stronger than the visible  light radiation, can move the electrons, being absorbed. Here is why you can't get a tan behind glass .

 I hope the answer to the initial question is now clear. Isn’t it amazing?  Behind ordinary  things, which seem simple and we usually take for granted, there is something much more complex and fascinating!

Thank you for reading. Till next time! 

Giordano  C.