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Bonds

The eternal mystery of the world is its comprehensibility - Albert Einstein. Bonds. Chemical Bonds. Chemical compounds are formed by the joining of two or more atoms. This point of union is called a bond. The bond means there is an attractive force between the atoms.

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Bonds

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  1. The eternal mystery of the world is its comprehensibility - Albert Einstein Bonds

  2. Chemical Bonds • Chemical compounds are formed by the joining of two or more atoms. • This point of union is called a bond. • The bond means there is an attractive force between the atoms. • Bonds are more like springs then sticks. Some atom movement is possible. • There are 3 main types of bonds, Ionic, Metallic and Covalent.

  3. Ionic Bonds • Ionic bonds are formed by a transfer of electrons. • One of the atoms gains the electron(s) that the other lost. • Both end up with full outer energy levels and opposite charges. • The oppositely charged ions are attracted to each other. • Many ions bond together forming networks. • This is shown in the diagram of NaCl to the right. • In the diagram, Na is red and Cl is green. • In this situation there really is no single molecule but there is a simplest formula..

  4. Ionic Bonds • Ionic bonds are formed by a transfer of electrons. • One of the atoms gains the electron(s) that the other lost. • Both end up with full outer energy levels and opposite charges.

  5. Ionic compounds and conduction • Electric current is moving charges. • Solid ionic compounds do not conduct electricity because the charged ions are locked in place. • When dissolved, ionic compounds disassociate or separate into their ions. • The solution can now conduct electricity because the ions are free to move. • A solid block of salt and a beaker of distilled water will not conduct electricity, but a beaker of salty water will!

  6. Metallic Bonds • The attraction between a metal atom’s nucleus and a neighboring atoms electrons is strong and packs the atoms closely together. • This causes the outermost energy levels of the atoms to overlap. • These outermost electrons are free to move from atom to atom. • This explains why metals are good conductors and why they are so flexible and malleable when compared to the non-metals.

  7. Covalent Bonds • A covalent bond forms when two or more atoms share valence electrons. • This occurs most often between elements in groups IVA, VA, VIA and VIIA. • The sharing of electrons allows each atom in the molecule to have a stable octet in its outermost energy level.

  8. Methane (CH4) • The methane molecule illustrated has 4 covalent bonds. • The bonds are between each hydrogen atom and the carbon atom. • The sharing of electrons means sometimes they are going around the carbon and sometimes they are going around the hydrogens. • In this way each element gets to have a full outer energy orbital.

  9. Polar Covalent bonds • The shared electrons in a covalent bond may not be shared equally. • Electrons are strongly attracted to atoms located to the upper right of the periodic table. • In the water molecule, the oxygen atom has a much stronger attraction for the electrons then either hydrogen. • This means that the electrons from the two hydrogens spend most of their time orbiting the oxygen atom. • Because of this unequal sharing a molecule of water has a negative and a positive end (poles).

  10. Water is Special! • Because of the polar nature of the water molecule it is attracted to itself! • Water molecules are attracted to each other and this is the main reason that such a small molecule is a liquid at room temperature!

  11. Many water molecules showing hydrogen bonding

  12. Ice Structure - note similarities to snowflakes!

  13. Glacial Blue ice - ice that is formed by the recrystallization of snow that is compacted in a glacier.

  14. Huge tabular iceberg from Antarctica

  15. Blue ice berg, Antarctica

  16. Carbon dioxide, polar covalent but with a twist! • In the CO2 molecule the oxygen atoms have the electrons more often than the carbon atoms. • This makes the oxygen ends of the molecule negative and the area between the oxygen and the carbon positive. • How does this explain the fact the CO2 is a gas at room temperature even though it is a much bigger molecule than water?

  17. Dry Ice • Dry ice is the solid form of the gas carbon dioxide.  • A full block, measuring about 10 inches square, weighs 50 lbs.  • The temperature of dry ice is 110° below zero.  • When handling dry ice, wear work gloves as the extremely low temperature will cause frostbite.  • Dry ice has many uses, chief among them as a refrigerant to prevent food form perishing and to ship blood products.

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