'A chemical reaction is a simple rearrangement of atoms leading to formation of newer substances(products). Hence, to favour the rearrangement,breaking of bonds in the reactants and making of bonds between atoms in the products occur.

Due to this in every chemical reaction there is involvement of energy (liberation or absorption depending on the bond energies of the elements in the reactant and the products). The energy involved may be light, heat or electrical energy.

All combustions (burning) are chemical reactions of a fuel with oxygen in which carbon-hydrogen and oxygen-oxygen bonds are broken in the reactants (except hydrogen) and carbon-oxygen and hydrogen-oxygen bonds are formed in the formation of the products.

The bond energies of these atoms are in such a way that the energy liberated is always more than the energy consumed for the breaking of bonds. The net energy is liberated in the form of both light and heat.'

When something is burnt, the atoms are heated to a high temperature and the electrons in the atoms are excited to higher levels than their ground (rest) state. It’s like saying the atoms are excited with all the energy. In order to get to their normal state, they get rid of their energy in the form of radiation. Light is just radiation that we can see. Another way to think about it is if something is hot, then it naturally wants to cool down. To cool down means to give off the heat energy to the surrounding air. The heat energy is given off in the form of an electromagnetic wave. The colour that we see in a bunsen burner for example, is to do with the temperature of the flame (in this case the air is being burnt). The coolest flames are yellow-ish and as the temperature increases, the type of radiation that is given off moves towards the blue end of the electromagnetic spectrum of visible light. Really really hot temperature flames would give off UV light (but we can’t see it cos it’s invisible to us) and that’s also why the sun gives off UV rays.

When something is burnt,the heat in the chemical reaction ‘excites’ electrons to higher energy levels. When the electron drops back down the energy is released and has a characteristic wavelength based on the type of atom being burned. This wavelength gives rise to the light we see and the colour differs depending on the wavelength.

When something is burnt, the atoms are heated to a high temperature and the electrons in the atoms are excited to higher levels than their ground (rest) state. It’s like saying the atoms are excited with all the energy. In order to get to their normal state, they get rid of their energy in the form of radiation. Light is just radiation that we can see. Another way to think about it is if something is hot, then it naturally wants to cool down. To cool down means to give off the heat energy to the surrounding air. The heat energy is given off in the form of an electromagnetic wave. The colour that we see in a bunsen burner for example, is to do with the temperature of the flame (in this case the air is being burnt). The coolest flames are yellow-ish and as the temperature increases, the type of radiation that is given off moves towards the blue end of the electromagnetic spectrum of visible light. Really really hot temperature flames would give off UV light (but we can’t see it cos it’s invisible to us) and that’s also why the sun gives off UV rays.