Unit #1Unit #2Unit #3Unit #4Unit #5Unit #6Unit #7Unit #8Unit #9Unit #10
spacerUNIT # 3  

spacerof the Atom

spacerAtomic Number - Number of Protons
spacerNumber of Electrons
spacerMass Number - Number of Neutrons
spacer3.2 Isotopes
spacer3.3 Arrangement
spacerof Electrons

spacerThe Bohr Model
spacerBohr Diagram
spacerThe Lewis Electron-dot Symbol
spacerThe Quantum Mechanical Model of the Atom
spacerElectrons in the sublevels

spacer3.4 Electron

spacerFilling Order of the Sublevels

spacerElectron Configuration Notations
spacerElectron Configuration for Atoms of the First 20 Elements
spacerElectron Configuration and the Periodic Table
spacer3.5 Atomic Mass
spacerCalculation of Atomic Mass
spacerCalculate the Atomic Mass of Carbon

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3.1 - Structure of the Atom

3.1.2 - The number of electrons in an atom

Now that we know how to determine the the number of protons in the nucleus for a particular element, determining the number of electrons is straight forward. We must remember that an atom is electrically neutral. Since each proton carries a +1 charge, there must be an equal number of electrons in the atom, as each electron carries a -1 charge.

The periodic table of elements SHOWS you the atomic number (or the number of protons) of each element. Take a look at the periodic table closely to verify the number of electrons for the first 10 elements by clicking on the symbol of the element.

Periodic Table of the Elements

Section 4.4
Electrons, Protons, and Neutrons. Atomic Number ..p83




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