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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!!!
Learn the rules!!! Rule the rules • CBr4 = carbon tetrabromide • CO2 = carbon dioxide • CO = carbon monoxide • P2O3 = diphosphorus trioxide
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 molecule HYDROGEN MOLECULE
Sharing doesn’t mean equal • Electronegativity: an atoms pull of electrons in a covalent bond. • Some pull stronger than others when sharing electrons • yarps
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 wawa • Non-polar things do not dissolve in polar things • Oil and wawa 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
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