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

3.1.1 - Atomic Number - The number of Protons in an atom

The number of protons in the nucleus of an atom is very important.

The number of protons:

  1. determines the identity of an element. (In section 2.4, we learned that elements are pure substances.)
    Click here to take a look at the identities of atoms having 1 to 10 protons in its nucleus.
  2. is also known as the atomic number of the atom.

The periodic table of elements SHOWS you the atomic number of each element. If you know where to look for the atomic number of an element on the periodic table, you would know the how many protons are in the nucleus of the element. Take a look at the periodic table closely to verify the number of protons 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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