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