<p>Chapter 9, Section 1, Page 258 – 260</p><p>An atom is made up of three things.</p><p>1 A proton i. The number of protons is the ATOMIC NUMBER ii. Protons are made up of quarks iii. Protons have a positive one charge (+1), exactly 2 A Neutron i. The number of neutrons is determined by subtracting the atomic number (see above) from the atomic mass (higher number), which follows the “-“ symbol of atoms ii. Neutrons are also made up of quarks iii. Neutrons have a charge of exactly “0”. They are neutral iv. The number of neutrons, plus the number of protons, equals the atomic mass</p><p>3 An Electron i. An almost massless particle ii. Charge of exactly negative one (-1) The Nucleus of an atom has a huge collection of positive particles in it. Why does it not blow itself apart (since similar charges repel, and all the protons have the same charge)?</p><p>The answer is the STRONG NUCLEAR FORCE. Four Forces of Nature</p><p>Gravity ~ weakest of all. Almost nothing is known about it. It is probably carried by a particle called a graviton. Electromagnetic ~ combination of electricity and magnetism. It is carried by the interaction of the electrical/magnetic fields. Weak Nuclear force ~ keeps atoms from changing elements. Strong Nuclear ~ holds the atom together. This is the strongest of all of the forces, and is the one broken with nuclear reactions.</p><p> http://aether.lbl.gov/www/tour/elements/stellar/strong/strong.htm l</p>