00:01:27
The second element helium has two protons, and the third element lithium has three protons. This goes on all the way up to the hundred and eighteenth element Oganesson, which has… that’s right a hundred and eighteen protons in its nucleus. By the way the number of protons in an atom is also called its atomic number, which you can see here on the periodic table of elements now electrons are much smaller than protons, and they zip around protons at lightning speed, making up something called an electron cloud around the atom. Electrons do this because they have a negative electrical charge, which always pulls towards the protons positive electrical charge. This pull between the positive protons and the negative electrons is called the electric force, and it’s always there. so whenever a free electron gets close enough to a lonely proton -zap- they’ll become part of the same atom. That’s why all the (stable) elements have the same number of electrons and protons.
00:02:57
So why do atoms need neutrons? Well without neutrons the electric force will cause the positively charged protons to push each other out of the atom. But there’s a stronger force that exists between neutrons and protons, which stops the protons from flying apart. It’s called the strong nuclear force, or strong force for short, and it kind of works like glue to hold the nucleus together. If there were no neutrons everything would simply be hydrogen.