Parts of the Atom and The Periodic Table Open Chemical Building Blocks Book to Page 85. Get chalkboards, chalk, and eraser

Nucleus Center of the atom. Makes majority of the atom’s mass. Made of Protons and Neutrons. Nucleus

Protons Part of the nucleus Have positive (+) charge Protons are the atomic number on the PT Protons = number of electrons

Neutrons Part of the nucleus Have neutral charge Varying neutrons make isotopes Find neutrons - Atomic Mass – Atomic Number (protons) = Neutrons

Mass Number Part of the nucleus Number of protons + neutrons

Isotopes Atoms with the same number of protons but different numbers on neutrons So you can change the number of neutrons and the element still maintains its identity Example: Carbon

Electrons Orbit around the nucleus Have negative (-) charge Electrons = the number of protons

Electrons – Energy Levels Energy levels are in the electron cloud and around the nucleus Each level has a set number of electrons that the level can hold up to Outer most level is for chemical bonding Energy levels are accurate until the 5 th energy level

Atoms have neutral charge # of Protons (+) = # of Electrons (-) = 0 charge Example: Hydrogen How many electrons does C have?

Electrons orbit in “shells” 1 st shell can fit 2 electrons 2 nd shell can fit 8 electrons 2 nd period/row 3 rd period/row 1 st period/row 3 rd shells can fit up to 18 electrons

Reading and Using the Periodic Table Mass

Atomic Number Definition: the number of protons in the nucleus Protons = Atomic Number = Electrons Tells us the identity of the element. Every element is defined by the number of protons in its nucleus

Atomic Mass Definition: the ~ mass of one atom of an element Tells us how much one atom weighs in atomic mass units. Mass