The Atom Protons, Electrons, and Neutrons

Picture an atom as a microscopic LEGO. Atoms come in a variety of shapes and sizes, and you can build larger structures out of them. Like a LEGO, an atom is extremely hard to break. In fact, so much energy is stored inside atoms that breaking them in half results in a nuclear explosion. 

Even though an atom is made of smaller pieces called subatomic particles, the atom is still considered the smallest possible unit of an element, because after you break an atom of an element into subatomic particles, the pieces lose the unique properties of that element. 

Virtually all substances cire made of atoms. The universe seems to use about 120 unique atomic LEGO blocks to build neat things like galaxies and people and whatnot. All atoms cire made of the Scime three subatomic particles the proton, the electron, and the neutron. Different types of atoms (in other words, different elements) have different combinations of these pcirticles, which gives each element unique properties. For example  

Two of the subatomic particles have a charge The proton is positive, and the electron is negative. Atomic charges are measured in multiples of the charge of a single proton. 

The must-know information about the three subatomic particles is in Table 3-1. Notice that protons and electrons have equal and opposite charges and that neutrons are neutral. Atoms always have an equal number of protons and electrons, so the overall charge of an atom is neutral (that is to say, zero). 

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