Atoms and empty space
Dear HIW, I really love your magazines, I could read one back to front so many times! I was just wondering, after Rutherford found out the nuclear atomic model was mainly empty space, what fills that empty space? Is it a vacuum? Thank you again for the amazing magazines!
Hi Alfie, thanks for your question. Ernest Rutherford is famous for his series of experiments that showed atoms are composed mostly of space. Performed along with physicist Hans Geiger and student Ernest Marsden, Rutherford’s experiments involved blasting a thin sheet of gold foil with alpha particles (the nuclei of helium atoms) and discovered that most would pass right through the foil, but a few were scattered. This occurred because most of the gold atoms were empty space, so the alpha particles could go straight through. The deflections were caused by the concentration of mass in the centre of the gold atoms – the nucleus. So if most atoms are empty space, why don’t objects just go through one another all the time? While the space within atoms is technically a vacuum and empty of other matter, electromagnetic fields still exist across them. When you sit in a chair, for example, the electrons in the atoms of your body and the chair repel one another. In fact, your body is effectively floating above the chair by a miniscule amount – around one ten-billionths of a metre (1x10-10 metres)! Things get even stranger when you consider the quantum nature of atoms. The electrons in an atom don’t orbit the nucleus like planets orbiting a star (although that comparison does help us understand simple atomic models). Instead, they can seemingly be in many places at once. To help picture this, think of a fan: when it’s off, you can see that there is space between the blades, but once you switch it on it looks as if the blades are occupying the entire space at all times. So to answer your question, yes, the space is technically a vacuum, but once you get into the quantum workings of atoms the space is never really ‘empty’. Thanks for writing to us, and we hope that answers your question for you.