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Ionic Bonding

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Ionic Bonding What makes an atom most stable? When the highest occupied energy level is filled with electrons the atom is stable, and probably will not react chemically. – PowerPoint PPT presentation

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Title: Ionic Bonding


1
Ionic Bonding
2
  • Ionic bonds form between a metal and a non-metal
    and dissolve easily in water.
  • In solution, ionic compounds easily dissolve to
    form ions.
  • Ionic bonds produce salts which tend to form
    crystals with high melting temperatures.

3
What makes an atom most stable?
  • When the highest occupied energy level is filled
    with electrons the atom is stable, and probably
    will not react chemically.
  • Elements in the noble gas family have the highest
    energy level filled and have the most stable
    electron configuration.

4
Electron Dot Diagrams(Lewis Structures)
  • The easiest way to see if an element is stable,
    is to draw its Lewis Dot structure showing only
    the valence electrons.
  • The Lewis Dot will allow you to see how many
    electrons an element needs to fill its outer
    shell and how it may react with other elements.
  • For instance oxygen has 6 valence electrons and
    thus can gain two electrons to fill its outer
    shell.
  • This means that oxygen could take 2 electrons
    from one other element or one each from two
    different elements.

5
OCTET RULE
  • Elements become happy when they have a complete
    outer shell. They are usually happy when the
    closest outer shell has 8 or 2 in the case of
    Helium.
  • Completing the outer shell is known as the Octet
    Rule (8 valence electrons)
  • In order to do this they will either lose or gain
    electrons.

6
Ion formation
  • If an atom has greater than 4 valence electrons
  • It will gain enough to make 8 (octet rule)
  • Becomes negatively charged ion (anion) because
    there are more electrons(-) than protons ()
  • This applies to elements in groups 5, 6, and 7
    because they are much closer to the noble gases
    thus it is much easier to gain than lose
    electrons.

7
Ion formation
  • If an atom has less than 4 valence electrons
  • It will lose those outer electrons so that its
    outermost shell of electrons is now full.
  • Becomes positively charged (cation) because there
    are more protons left than electrons.
  • This applies to elements in Groups 1, 2, and 3
    because it is easier to lose electrons than gain
    to fill the outermost shell.

8
Ionic bonds
  • Once positive and negative ions are formed, they
    are attracted to each other.
  • They form a chemical bond known as an ionic bond
    the force that holds cations and anions
    together results from the transfer of electrons
    from one element to another.
  • http//www.youtube.com/watch?v5IJqPU11ngYfeature
    player_detailpage

9
Practice with Ionic Bonding
  • Using the Lewis Dot models for each element, show
    the ions, with their oxidation number, that would
    form for each group
  • Potassium (K) and Bromine (Br)
  • Magnesium (Mg) and Chlorine (Cl)
  • Lithium (Li) and Oxygen (O)
  • Next, using the ions you formed, show the
    transfer of electrons for each group (remember to
    use Lewis Dot!!)
  • Finally determine the formula for each new
    compound that is formed. (subscript number of
    each element used.)

10
Oxidation Number vs. Subscripts
  • Ionic bonding is when two ions bond to each other
    forming an ionic compound.
  • Ex. One Na (sodium ion)(METAL) and one Cl-
    (chloride ion)(Non-metal) bond to make NaCl
    (sodium chloride)
  • One Mg 2 (magnesium ion) and two F - (fluoride
    ions) bond to make MgF2 (magnesium fluoride)
  • The number at the top of the ion is the oxidation
    number. (This is the number of electrons needed
    to reach a full outer shell plus the overall
    charge of the element after the loss or gain of
    electrons)
  • Once the ions combine you have a subscript that
    tells how many of each type of atom were needed
    to form a neutral compound. (Mg3N2)

11
Naming Ionic Compounds
  • The rules for naming ionic compounds are
  • Ex. Na Cl NaCl
  • Step 1 Name the metal/cation first
  • Sodium
  • Step 2 Name the non-metal/anion second
  • Chlorine
  • Step 3 Drop the ending (last syllable) of the
    anion listed and replace it with ide.
  • Result would be Sodium Chloride
  • Try naming these ionic compounds
  • KBr, MgCl2, Li2O, Na3N
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