Chemical Bonding. I. Introduction A. Types of Chemical Bonds – forces that hold two atom together...
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Transcript of Chemical Bonding. I. Introduction A. Types of Chemical Bonds – forces that hold two atom together...
![Page 1: Chemical Bonding. I. Introduction A. Types of Chemical Bonds – forces that hold two atom together 1. Ionic Bonds – occur b/w a metal & a nonmetal 2.](https://reader034.fdocuments.us/reader034/viewer/2022051516/56649e4c5503460f94b41e25/html5/thumbnails/1.jpg)
Chemical Bonding
![Page 2: Chemical Bonding. I. Introduction A. Types of Chemical Bonds – forces that hold two atom together 1. Ionic Bonds – occur b/w a metal & a nonmetal 2.](https://reader034.fdocuments.us/reader034/viewer/2022051516/56649e4c5503460f94b41e25/html5/thumbnails/2.jpg)
I. Introduction
A. Types of Chemical Bonds – forces that hold two atom together 1. Ionic Bonds – occur b/w a metal & a
nonmetal 2. Covalent Bonds – occur b/w 2
nonmetals & in polyatomic ions a. Polar Covalent Bonds -
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B. Distinguishing b/w Types of Bonds 1. Electronegativity – ability of an atom to
attract electron’s to itself.
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2. Bond Polarity: You can use the element’s electronegativities to determine the polarity of the bond – Just find the difference b/w the 2 numbers
0 – 0.4 Covalent bond 0.41 – 0.99 Polar Covalent bond > 1.00 Ionic bond
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Determine the Polarity!
1. H – O 2. C – N 3. K – F 4. S – O 5. Al - P
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What Polarity Looks Like
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3. Dipole Moments – When a bond is polar… 1 side of the molecule is more positive and the other side is more negative.
Why? Because the electrons are being pulled toward the more electronegative element.
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Dipole Moments
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Why is Water’s Dipole Moment So Important?
It has a huge affect on its properties! It’s so important, it has a specific name,
it’s called HYDROGEN BONDING.
It is crucial to life on Earth! Polar water molecules can surround &
attract positive & negative ions which allows materials to dissolve in water!
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It’s polarity also means that water molecules are attracted to each other
A LOT of ENERGY is needed to change H2O from a liquid to a gas because the attraction must be overcome to separate 1 H2O molecule from another.
So what?!?! This causes water on Earth, at Earth’s temperatures, to remain a liquid. OTHERWISE, it would all be a gas and the oceans would be empty!!!!
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II. Ionic Bonds
A. A strong bond caused by the transfer of electrons from a cation (metal) to an anion (nonmetal). 1. Why? The driving force behind this bonding is
that all elements want to have a completely filled outermost energy level! [OCTET RULE]
a.) These outermost electrons are called the VALENCE ELECTRONS
b.) Metals LOSE valence electrons to be stable. c.) Nonmetals GAIN valence electrons to be
stable.
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Valence Electrons1e- 8e-
2e- 3e- 4e- 5e- 6e- 7e-
2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e-
1e- 1e-
1e-
2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e- 2e-
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Let’s try it!
1. Na and O 2. Al and F 3. Ca and S 4. Mg and P
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B. Ionic Bonding And Structures of Ionic Compounds 1. Ionic compounds are
a. very stable, huge amounts of energy necessary to break them apart
b. high melting & boiling points NaCl has a melting point = ~800°C
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2. Structures of Ionic Compounds a. When you write the formula for an ionic
compound, you are writing its empirical formula.
b. In reality, the actual solid contains tremendous amounts & equal numbers of cations and anions packed together so that the attractions b/w them are maximized.
1.) Remember that cations are always smaller than anions. WHY?
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III. Covalent Bonding
A. Sharing electrons! 1. All bonding involves valence electrons
ONLY!!!!!! 2. Covalent bonds occur when 2 atoms (usually
nonmetals) share electrons. 3. LEWIS STRUCTURE – a representation of a
molecule that shows how the valence electrons are arranged among the atoms in the molecule.
Thought up by G.N. Lewis while teaching a chemistry class in 1902.
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See attached page for writing Lewis Structures!
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B. Structures – VSEPR Model 1. Valence Shell Electron Pair Repulsion
Model a. Useful for predicting the geometric shape
of molecules formed from nonmetals! b. The structure around a given atom is
determined by minimizing repulsions between electron pairs.
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Metallic Bonding
How atoms are held together in the solid. Metals hold onto their valence electrons
very weakly. Think of them as positive ions floating in
a sea of electrons!
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Sea of Electrons!
Electrons are free to move through the solid.
Metals conduct electricity.
+ + + ++ + + +
+ + + +
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Metals are malleable!
Hammered into shape (bend). Ductile - drawn into wires.
+ + + ++ + + +
+ + + +
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Malleable Electrons allow atoms to slide by.
+ + + +
+ + ++ + + +
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Alloys
Solutions made by dissolving metal into other elements- usually metals.
Melt them together and cool them. If the atoms of the metals are about the
same size, they substitute for each other Called a substitutional alloy
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Metal A
Metal B
+
Substitutional alloy
Bronze – Copper and Tin
Brass- 60 % Copper 39% Zinc and 1%Tin
18 carat gold- 75% gold, 25%Ag or Cu
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Alloys
If they are different sizes the small one will fit into the spaces of the larger one
Called and interstitial alloy
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Metal A
+
Metal B
Interstitial Alloy
Steel – 99% iron 1 % C
Cast iron- 96% Iron, 4%C
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Alloys
Making an alloy is still just a mixture Blend the properties Still held together with metallic bonding Most of the metals we use daily are
alloys. Designed for a purpose