l4 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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CIVE 2700 – Civil Engineering Materials, Winter 2007 1 Atomic Structure and Interatomic Bonding Professor George Hadjisophocleous, Ph.D., P.Eng. Carleton University Department of Civil and Environmental Engineering Ottawa, Ontario CIVE 2700 – Civil Engineering materials, Winter 2007, 4.2 Outline • Objectives • Structure of atom • Interatomic bonding • Bonding energies • Material properties
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CIVE 2700 – Civil Engineering Materials, Winter 2007 2 CIVE 2700 – Civil Engineering materials, Winter 2007, 4.3 Objectives • Learn bonding types between atoms and molecules • Learn how interatomic bonding affects properties of materials CIVE 2700 – Civil Engineering materials, Winter 2007, 4.4 Atomic Structure • Atoms are made up of 3 types of particles Electrons Protons Neutrons .
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CIVE 2700 – Civil Engineering Materials, Winter 2007 3 CIVE 2700 – Civil Engineering materials, Winter 2007, 4.5 Atomic Structure • These particles have different properties. Electrons are tiny, very light particles that have a negative electrical charge (-). Protons are much larger and heavier than electrons and have the opposite charge, protons have a positive charge. Neutrons are large and heavy like protons, however neutrons have no electrical charge. • Each atom is made up of a combination of these particles. CIVE 2700 – Civil Engineering materials, Winter 2007, 4.6 Hydrogen Atom • The atom below, is made up of one proton and one electron, is called hydrogen. • The proton and electron stay together because just like two magnets, the opposite electrical charges attract each other
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CIVE 2700 – Civil Engineering Materials, Winter 2007 4 CIVE 2700 – Civil Engineering materials, Winter 2007, 4.7 Helium Atom Helium is the 2nd simplest atom. It has two protons in its nucleus and two electrons spinning around the nucleus. Because the 2 protons in the nucleus have the same charge on them, they would tend to repel each other, and the nucleus would fall apart. To keep the nucleus from pushing apart, helium has two neutrons in its nucleus. Neutrons have no electrical charge on them and act as a sort of nuclear glue, holding the protons, and thus the nucleus, together CIVE 2700 – Civil Engineering materials, Winter 2007, 4.8 Atoms • Mass of proton and neutron = 1.67 x 10 -27 kg • Mass of electron = 9.11 x 10 -31 kg • A chemical element is characterized by the number of protons in the nucleus: atomic number (Z). • For an electrically neutral atom Z = number of electrons . • Atomic number ranges from 1 for hydrogen to 92 for uranium. • Atomic mass is the sum of masses of protons and neutrons.
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CIVE 2700 – Civil Engineering Materials, Winter 2007 5 CIVE 2700 – Civil Engineering materials, Winter 2007, 4.9 Atoms • Number of protons is the same for all atoms of a given element. • Number of neutrons
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This note was uploaded on 11/13/2011 for the course CIVE 2*** taught by Professor - during the Spring '11 term at Carleton CA.

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l4 - CIVE 2700 Civil Engineering Materials, Winter 2007...

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