although no one has yet found a way of getting a close-up view of an atom different experiments have made it possible to build up a picture or model of what atoms consist of the colors in these models are of course used simply to distinguish between different particles in the center of an atom is a nucleus this is made up of even smaller or subatomic particles called protons and neutrons the protons each carry a positive electrical charge the neutrons are as heavy as protons but carry no charge this means that overall the nucleus is positively charged and orbiting around it are negatively charged particles called electrons the size of the negative charge carried by an electron is equal to the positive charge carried by a proton now the electrons are moving at incredible speed in fact 3/4 of the speed of light so what's stops them shooting off in any direction if we could pull an atom apart into its components we'd see that a neutral atom has the same number of electrons as protons and it's the force of attraction between the positive and negative charges that prevents the electrons escaping each type of atom is identified by the number of protons and electrons it has a hydrogen atom has just one proton and one electron an oxygen atom has eight protons and eight electrons an iron atom has 26 protons and 26 electrons but this is not enough to explain the behavior and properties of most substances