covalent compounds the “why can’t everybody just be friends” bonding…
Post on 22-Dec-2015
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Covalent compounds
The “why can’t everybody just be friends” bonding…
• So…. How did you get full outside energy levels of valence electrons this time???
• Oh…• Covalent Compounds: 2 or more non-metals
held together by a covalent bond.• Covalent bond: the sharing of electrons
between atoms.• Like two people listening to the same song
with ear buds/headphones• yarp
Same goal of universe…• Lazy… low in energy, stability• How did ions fill up their outer energy level??• What held together ionic compounds??• Covalent compounds still want full outer
energy levels of e- . But…• they do it why sharing• Show it on the periodic table!!!!!!!• Yarp
How come??? Why share???• Take a step back… use old knowledge – Metals… gain or lose e- ???– Nonmetals … gain or lose e- ???
• Ionic compounds have metal and nonmetal– one loses e- , the other one gains e- …
• Covalent compounds only made of nonmetals– Who will lose e- ???
• Correct… makes sense?• yarpness
Why don’t you draw a picture… it’ll last longer…
• Show the story of 2 non-metals eventually sharing an electron
How do we show the sharing???• we call it Electron dot structures.• the cheerio lab…• and here are the rules!!!
• 1. Determine the total # of valence electrons in a compound
• Add up all valence electrons of each atom in the compound
• yarp
• 2. Arrange the e- to show complete outer energy levels for ALL atoms in the compound!!!!
• Each atom should have 4 pairs (8 e-) around them.
• Except hydrogen = 1 pair (2 e-)• Are side-by-side or up and down.• Not diagonal!!! • yarp
• 3. Replace each shared pair of electrons with a connecting line
• This line represents a pair of electrons and a covalent bond!!!!
• yarp
Examples… show bond type!!!• CBr4 = carbon tetrabromide
• CO2 = carbon dioxide
• CO = carbon monoxide
Naming of covalent compounds
• Need prefix memorized!!!
1 = mono 6 = hexa2 = di 7 = hepta3 = tri 8 = octa4 = tetra 9 = nona5 = penta 10 = deca
• Learn the rules!!! Rule the rules
• CBr4 = carbon tetrabromide
• CO2 = carbon dioxide
• CO = carbon monoxide
• P2O3 = diphosphorus trioxide
Compare covalent and ionics pt. 1characteristic Covalent ionicAtom types (metal, nonmetals, etc)
How bondedUnique naming tricks
More practice if ya need it!!! e- dot• Sulfur dichloride
• Freon = CCl2F2
And even more practice… awesome
• Work hard…• Yarp more
Covalent part 2
Ya better have done the property lab
Did you???• Summarize the covalent lab in class???• Compare covalent compound properties to
ionic compound properties???• Yes???• It should have taken some time…• Yes???• Sweet move on!!!!• Yarp!
Diatomic molecules• Two of the same atom covalently bonded
together…• Memorize the 7
All are followed by the word moleculeHYDROGEN MOLECULE
H2 = hydrogen Cl2 = chlorineN2 = nitrogen Br2 = bromineO2 = oxygen I2 = iodineF2 = fluorine
Sharing doesn’t mean equal
• Electronegativity: an atoms pull of electrons in a covalent bond.
• Some pull stronger than others when sharing electrons
• yarps
• Subtract the difference in Electronegativity
Bond type How electrons are shared
Electronegativity difference
Non –polar Equal sharing # ≤ 0.4Polar Unequal sharing # > 0.4Ionic Not sharing,
taking# > 2.1
Electronegativity #’s!!!
Enough…!!!! For now!!!!• Use this to work on the model lab…• Lots of electron dot practice here…• Get to work…• And you will like it!!!
3-D shapes
Tinker toy coolness!!!
5 shapes to talk about• Draw em on da chalkboard!!! Show models• Show angles and shared/no shared• Linear = line• Tetrahedral = tripod with neck• Pyramidal = tripod no neck• Bent = bent• Trigonal planar = flat… like pancake• yarp
Add some polarity• How the electrons are shared in a covalent
bond make a big difference.• Non-polar = equal sharing and balance of
electron and charge– Like oil
• Polar = unequal sharing and a shift in negative charge– Like water
• yarp
Like dissolves like• Polar/ionic things dissolve in polar things– Things dissolving in wa wa
• Non-polar things do not dissolve in polar things– Oil and wa wa don’t mix
• How do you know if it is polar or non polar?• Yarp that
Compare Electronegativity• To find polarity• 1. identify the 2 elements sharing in a bond• 2. subtract bigger Electronegativity from
smaller Electronegativity.• 3. compare difference
Bond type How electrons are shared
Electronegativity difference
Non –polar Equal sharing # ≤ 0.4
Polar Unequal sharing # > 0.4
Ionic Not sharing, taking # > 2.1
Do some examples• Carbon tetrahydride• Chloromethane (you won’t have this name)• Carbon dioxide• water
Now you know the bonds • You can also look at the entire molecule as
well• Polar molecule = an unbalance when
comparing the bonds of the molecule• Non-polar molecule = a balance when
comparing the bonds…• The rules get detailed… we no bother• Show in the drawn molecules• yarp
We be done…
• Is good• Is done…• Is review• yarp
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