Transcript Ionic and Metallic Bonding

Ionic and Metallic Bonding
Chapter 7
The Octet Rule
• The Octet Rule: When forming compounds,
atoms tend to achieve the electron
configuration of a noble gas.
• An octet is a set of 8.
• Exception: H and He only need 2 electrons to
fill their valence shells!
The Octet Rule
• Metals tend to lose valence electrons and
empty their outer shells, leaving 8 electrons in
the shell below.
• Non-metals tend to gain or share electrons to
fill up their outer shells so there are 8
electrons in it.
Cation
• If an atom LOSES an electron, it becomes
slightly POSITIVE which makes it a CATION.
Anion
• If an atom GAINS an electron, it becomes
slightly NEGATIVE, and is called an ANION.
• Anions end in –ide (like Fluroide)
Ionic Bonds
• When anions and cations combine, they form
ionic compounds.
• These are held together by ionic bonds, bonds
in which electrons are transferred from one
atom to another.
• They are electrically neutral.
Properties of Ionic Compounds
• Most ionic compounds are crystalline solids at
room temperature.
• Ionic compounds have high melting points,
and can conduct an electric current when
dissolved in water.
Fluorite (CaF2)
Aragonite (CaC03)
Pyrite (FeS2)
Bonding in Metals
• Metals are made of closely packed cations
(not neutral atoms).
• The valence electrons metals are described as
a “sea of electrons”
Alloys
• Alloys are mixtures composed of two or more
elements, at least one of which is a metal.
• They have more desirable properties than
plain metal (harder, more durable)
• Examples include: sterling silver, bronze, and
steel.
• Uses: jewelry, coins, building material
Making Ionic Compounds
• Oxidation numbers tell you what charge an
ion of an atom has.
Group
Electrons
Charge of Atom
I (Alkali metals)
Lose 1 electron
+1
II (Alkaline Earth)
Lose 2 electrons
+2
III
Lose 3 electrons
+3
V
Gain 3 electrons
-3
VI
Gain 2 electrons
-2
VII (Halogens)
Gain 1 electron
-1
Practice
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Create an ionic compound containing Cl and Na.
1. Which is the metal?
2. What is its oxidation number?
3. What is the non-metals oxidation number?
4. Add enough of each to make the charge 0.
5. Name the compound.
Practice
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Create an ionic compound containing Cl and Na.
1. Which is the metal? Na
2. What is its oxidation number? +1
3. What is the non-metals oxidation number? -1
4. Add enough of each to make the charge 0.
1 atom of Na and 1 atom of Cl: NaCl
5. Name the compound. Sodium Chloride
Practice
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Create an ionic compound containing Mg and Cl.
1. Which is the metal?
2. What is its oxidation number?
3. What is the non-metals oxidation number?
4. Add enough of each to make the charge 0.
5. Name the compound.
Practice
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Create an ionic compound containing Mg and Cl.
1. Which is the metal? Mg
2. What is its oxidation number? +2
3. What is the non-metals oxidation number? -1
4. Add enough of each to make the charge 0.
1 Mg and 2 Cl would add up to 0: MgCl2
5. Name the compound. Magnesium chloride
Practice
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Create an ionic compound containing Li and N.
1. Which is the metal?
2. What is its oxidation number?
3. What is the non-metals oxidation number?
4. Add enough of each to make the charge 0.
5. Name the compound.
Practice
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Create an ionic compound containing Li and N.
1. Which is the metal? Li
2. What is its oxidation number? +1
3. What is the non-metals oxidation number? -3
4. Add enough of each to make the charge 0.
3 Li and 1 N would add up to 0: Li3N
5. Name the compound. Lithium nitride
Agenda
• 1. Complete the “Ionic and Metallic
Compounds” worksheet. Turn this in when
you are done, or it’s homework and due next
class.
• 2. Finish the Chapter 7 and 8 Questions from
the red book.