Presentation on theme: "Reviewing Subatomic Particles"— Presentation transcript:
1 Reviewing Subatomic Particles Nucleus contains:1. Protons -2. Neutrons -Positively charged, mass of 1 amuNo charge, mass of 1 amuElectrons -Negatively charged, mass of 1/1840 amuAtomic number =# of Protons =# of ElectronsMass Number =# of protons + # of neutrons
2 Distinguishing Between Atoms Atomic Number (Z) – The number of protons in the nucleus of the atom.In a neutral atom the # of protons (+) = the # of electrons (-)Nuclear Charge = # of protons
3 The Nucleus Protons (positive charge) Neutrons (No Charge) Electrons (negative charge) are found in a cloud outside of the nucleus.
4 Mass Number (A) = number of protons + the number of neutrons Most of the mass of an atom is found in the nucleus.The mass number is given after the name of the element (example: Carbon – 12)Isotope – Atoms that have the same number of protons but different numbers of neutrons.Example: Carbon – 12 and Carbon – 14
5 U Atomic Symbols 238 92 Mass Number = protons + neutrons Ion Charge (if there is one)Symbol = ElementAtomic Number = Protons
6 Atomic MassesAtomic Mass Unit (AMU) – Using carbon-12 as a base unit, the mass is defined as 1/12 the mass of the carbon-12 isotope.mass of a proton = 1 amumass of a neutron = 1 amu.Atomic Mass – The weighted average mass of the isotopes of an element.
7 How to Calculate the Average Atomic Mass Change the percentages back to the decimal valuesExample: % = .9994Multiply the mass number by the decimal of the percent.Example: Carbon – 12 (.9994 x 12)Add all of the products of the mass numbers and the decimal percentages