What Are Atoms Like

Except for the fact that the atom is so small, and the sun and the planets so huge, they are much alike.
In this centre are one or more particles called protons.
Revolving around this centre, or nucleus, are particles of negative electricity called electrons.
It takes 1,845 electrons to weigh as much as one proton.
You may have seen how this works with two magnets.
Touch the positive end of one magnet to the negative end of another and they will cling together; but two negative ends, or two positive ends, will not stay together.
Every atom has exactly as many protons as electrons, so that the positive and the negative balance each other.
All other atoms are heavier than hydrogen, having two or more protons in their nuclei.
For example, the atomic number of hydrogen is 1.
There is still another particle that goes to make up the atom.
A neutron weighs about the same as a proton, but it does not have any electrical charge at all, either positive or negative.
Neutrons add to the weight of the atom.
Different atoms of the same element are called isotopes.
The uranium atom always has 92 protons is its nucleus, but one of its isotopes, called U-238, has 146 neutrons (146 neutrons + 92 protons = 238), while the isotope called U-235 has 143 neutrons in its nucleus ( 143 + 92 = 235).
A stable element is composed of atoms that do not rapidly throw off their particles, their protons, neutrons, and electrons- in the form of rays.
The heavier elements are often unstable.
This is explained in the articles on atomic energy and radio activity.
They never succeeded, but today it is possible to change some elements into other elements by changing the number of protons, neutrons and electrons in them.
This is very hard to do, because the forces binding the particles together are very great.