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ChemCatalyst 10/23/15 Today you need your notebook and Laptop. Open the PowerPoint on the weebly. In your notebook answer the following questions: 1. What two particles does the nucleus contain? 2. Which subatomic particle has the smallest mass? 3. What is the electrical charge of a proton? Electron? Neutron? The Atom: Calculating Protons, Neutron, and Electrons Chemistry/Pre-AP Chemistry Ms. Lizette Gutierrez Austin High School Periodic Table Information Atomic Symbol • Atomic Symbol • Shorthand notation of one (uppercase) or two letters (1 uppercase and 1 lowercase) for an element • Derived from the scientific names of the chemical elements • S for sulfur • Cl for chlorine • Zn for zinc • Some date back to Latin names • Au (aurum) for gold • Pb (plumbum) for lead. • Others are named for people or places • Es, Einsteinium for Einstein • Cf, Californium for California • Md, Mendelevium for Mendeleev Periodic Table Information Atomic Number • Discovered around 1913 by a Scientist name Henry Moseley • Atomic Number is the number of protons in the nucleus of an atom. • The atoms of each element differ from the atom of the element before it by one proton. • In atoms that are electrically neutral, atomic number also is the number of electrons. Periodic Table Information Atomic Mass • Atomic Mass (mass number) – the mass of an individual atom of a particular element. – Units are in amu (atomic mass units) • It was determined that the nucleus accounts for almost all the mass of the atom. • Both the proton and the neutron are about 2,000 times more massive than a tiny electron. Using the Periodic Table to Calculate Protons, Neutrons, and Electrons of an Atom • Protons = Atomic Number • Electrons = Atomic number (assume neutral atom) • Neutrons = You can estimate number of neutrons in an atom by taking the atomic mass (rounded to the nearest whole number) minus the atomic number. Classroom Example #1 Calculate the Number of p, n, and e for Lithium? Number of protons = 3 Number of electrons = 3 Number of neutrons 7 (6.941) – 3 = 4 Classroom Example #2 # protons = # electrons = 12 12 # neutrons = 24 -12= 12 Classroom Example #3 # protons = # electrons = 18 18 # neutrons = 40 -18= 22 Classroom Example #4 # protons = # electrons = 36 36 # neutrons = 84 -36= 48