read section 9.3 (pages 252- 255) in the textbook and do problems 30-34 on page 255. check your...
TRANSCRIPT
Read section 9.3 (pages 252-255) in the textbook and do problems 30-34 on page 255.
Check your answers in the back of the book, on page 926.
Homework
Daily Quiz 250
Name these molecules:
Name these acids:
Daily Quiz 250
Name these molecules:
1.NO2
2.N2O
Name these acids:
3.H3P
4.H3PO4
Daily Quiz 250
Name these molecules:
1.NO2 nitrogen dioxide
2.N2O
Name these acids:
3.H3P
4. H3PO4
Daily Quiz 250
Name these molecules:
1.NO2 nitrogen dioxide
2.N2O dinitrogen monoxide
Name these acids:
3.H3P
4. H3PO4
Daily Quiz 250
Name these molecules:
1.NO2 nitrogen dioxide
2.N2O dinitrogen monoxide
Name these acids:
3.H3P hydrophosphoric acid
4. H3PO4
Daily Quiz 250
Name these molecules:
1.NO2 nitrogen dioxide
2.N2O dinitrogen monoxide
Name these acids:
3.H3P hydrophosphoric acid
4.H3PO4 phosphoric acid
Daily Quiz 250
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Molecular Structures
Molecular Structures
NH3
Molecular StructuresStep 1a:
Hydrogen is always terminal (at the end) It can only form one bond.
NH3
Molecular StructuresStep 1b:
The atom with the least attraction for electrons is in the middle. Usually this atom is towards the left side of the periodic table
NH3
Molecular StructuresStep 1b:
The atom with the least attraction for electrons is in the middle. Usually this atom is towards the left side of the periodic table.
H N H
H
Molecular StructuresStep 2:
Count all the valance electrons (electrons in the outer shells)
H N H
H
Molecular StructuresStep 2:
Count all the valance electrons (electrons in the outer shells)
H N H
H
1 1
1
5
Molecular StructuresStep 2:
Count all the valance electrons (electrons in the outer shells).
1 + 1 + 1 + 5 = 8
H N H
H
1 1
1
5
Molecular StructuresStep 3:
Divide by two to find the number of bonding pairs of electrons
H N H
H
8
Molecular StructuresStep 3:
Divide by two to find the number of bonding pairs of electrons.
8 ÷ 2 = 4
H N H
H
Molecular StructuresStep 4:
Put one bonding pair (a single bond) between the central atom and each terminal atom
H N H
H
4
Molecular StructuresStep 5:
How many pairs of electrons do you still have left?
H N H
H
4
Molecular StructuresStep 5:
How many pairs of electrons do you still have left?
H N H
H
4 – 3 = 1
Molecular StructuresStep 5:
How many pairs of electrons do you still have left? Add these to the terminal atom first, then the central atom
H N H
H
4 – 3 = 1
Molecular StructuresStep 5:
How many pairs of electrons do you still have left? Add these to the terminal atom first, then the central atom.
H N H
H
This is called a
“lone pair”
Molecular StructuresStep 6:
Are you done?
H N H
H
Molecular StructuresStep 6:
Are you done? Count the electrons associated with each atom
H N H
H
Molecular StructuresStep 6:
Are you done? Count the electrons associated with each atom.
H N H
H2
2 22
Molecular StructuresStep 6:
If they add up to eight (or two for H), then you’re done
2 + 2 + 2 + 2 + 8
H N H
H2
2 22
Molecular StructuresStep 6:
If they add up to eight (or two for H), then you’re done.
If they don’t add up to eight, you need to take a lone pair from one of the terminal atoms to make a double or triple bond.
Molecular StructuresRemember:
Hydrogen atoms want 2 electrons
Molecular StructuresRemember:
Hydrogen atoms want 2 electrons
Most other atoms want 8 electrons
Molecular StructuresRemember:
Hydrogen atoms want 2 electrons
Most other atoms want 8 electrons
Polyatomic ions will have extra electrons (if they’re negative) or fewer (if they’re positive).
Molecular StructuresLet’s try another…
CO2
Molecular StructuresStep 1:
CO2
Molecular StructuresStep 1:
Hydrogens terminal
Leftmost element central
CO2
Molecular StructuresStep 1:
Hydrogens terminal
Leftmost element central
O C O
Molecular StructuresStep 2:
O C O
Molecular StructuresStep 2:
Count valence electrons
O C O
Molecular StructuresStep 2:
Count valence electrons
O C O46 6
Molecular StructuresStep 2:
Count valence electrons
6 + 4 + 6 = 16
O C O46 6
Molecular StructuresStep 3:
16 valence electrons
O C O
Molecular StructuresStep 3:
Count pairs of electrons
16 valence electrons
O C O
Molecular StructuresStep 3:
Count pairs of electrons
16 ÷ 2 = 8
O C O
Molecular StructuresStep 4:
8 pairs of electrons
O C O
Molecular StructuresStep 4:
Put bonds between atoms
8 pairs of electrons
O C O
Molecular StructuresStep 4:
Put bonds between atoms
8 pairs of electrons
O C O
Molecular StructuresStep 5:
8 pairs of electrons
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 pairs of electrons
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 5: How many left?
Add to terminal, then to central.
8 – 2 = 6
O C O
Molecular StructuresStep 6:
O C O
Molecular StructuresStep 6:
Are we done yet?
O C O
Molecular StructuresStep 6:
Are we done yet?
O C O2
2
2
2
Molecular StructuresStep 6:
Are we done yet?
O C O2
2
2
2√
Molecular StructuresStep 6:
Are we done yet?
O C O22 √
Molecular StructuresStep 6:
Are we done yet?
O C O22 √x
Molecular StructuresStep 6:
Are we done yet?
O C O2 2 √x2
2 √
Molecular StructuresStep 6:
Are we done yet?
O C O2 2 √x2
2√
Molecular StructuresStep 6:
Are we done yet?
O C O√x√
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√x√
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√x√
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√x√
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√x√ 22 2
2
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√√√ 22 2
2
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√√√
Molecular StructuresStep 6:
Are we done yet?
Take lone pairs to make multiple bonds
O C O√√√
Read section 9.3 (pages 252-255) in the textbook and do problems 30-34 on page 255.
Check your answers in the back of the book, on page 926.
.
Homework