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Notes: Bonding 10-18-00


Chemical Bonding: The combining of  atoms of elements to form new substances.

Valence Electrons: The electrons in the outermost energy level.

Chemical bonding depends on the valence electrons (because these are the electrons that can interact w/ other atoms).

energy levels (where electrons live):
First Energy- can hold up to 2 electrons
Second - Can hold up to eight.

Atoms are happy (they do not react) when their outer energy level is full.
    ex. The Noble Gases are inert (don’t react w/ anything) because their outer shell is full.

For Web example:
Barium has 2 electrons in its outer shell
Flourine has 7 (THEY BOTH WANT 8)
Now Go To Bond Animation and see what happens!

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Notes cont...

The above was a demonstration of an ionic bond forming.
Ionic bonds are bonds that involve the transfering of electrons.  (Stealing of electrons)

Positive ions form when electrons are lost...
    Na tends to lose 1 electron.  So it has a +1 charge.
Negative ions form when electrons are gained...
    Cl tends to take 1 electron.  So it has a -1 charge.

After the transfering is done, the charges do the work.  Opposites attract.  The only goal is that the total charge is zero.
    Na+1    Cl-1   ...   NaCl
    Al+3    O-2    ...   Al2O3

Ionization: The process of removing electrons to form an ion.  (This process takes energy)
Ionization Energy: Low for atoms w/ few valence electrons (they are more than happy to lose them) and high for those w/ almost a complete shell (they would rather gain a couple).

Electron Affinity: The tendency for atoms to attract electrons.  Fluorine has a high electron affinity...Why?...What other elements have a high electron affinity?

One last thing about ionic compounds...They like to form crystal lattice structures.  They fit together like puzzle pieces in a regular repeating pattern.

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Covalent compounds (MOLECULES)

DO NOT FORM IONS!!!
Covalent bonds arise from a sharing of electrons.  The nucleus(+) of each atom attracts the electrons(-).

LEWIS DOT STRUCTURES: electron dot diagram.  
    (See the link below any more questions, ask me or the book page 183-182)

Metallic Bonds

A network of positively charged metal nuclei and free roaming electrons (a common electron cloud).  What properties of metals does this help to explain?




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*  Special Note:
         The column (excluding transitions) tells you how many valence electrons.  The row tells you how many energy levels.

Draw dots around the symbols, single first then double.
Connect single dot s to single dots of other (oppositely charged) element.  Do this till all single dots are gone!
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My Quia activities and quizzes
Bonding
https://www.quia.com/jg/14037.html
GREAT STUDY GAME!!!
Predicting Ions
https://www.quia.com/pop/1603.html
Practice for Quiz!
Useful links
Last updated  2008/09/28 05:23:08 PDTHits  572