Sec. 6.2: “Drawing and Naming Molecules” Day 1
1. Both _____________ and _______________ bonds involve ____________ electrons,
the electrons found in the ______________ energy level of an atom that determine the
atom’s _______________ properties.
2. Who came up with a system to represent the valence electrons of an atom?
_____________________________________________________________
a. This system, known as ____________________ diagrams, or _____________
structures, uses ___________to represent __________________ electrons.
3. Lewis structures: a structural formula in which _______________ are represented by
__________. Dot pairs or ______________ between atomic symbols represent shared
________________ in _______________ bonds.
a. A Lewis structure shows only the ____________ electrons, not __________ of
the electrons in an atom.
4. How do you know how many valence electrons an atom has?
__________________________________________________________________
5. As you move from left to right across a ______________, each element has an
additional valence _______________.
a. These valence electrons are represented by _________ on each side of the
element’s symbol.
Examples: Li: _______ Be: ________ B: _______
C: _________
6. You do _________ begin to _______ dots until all four sides of the element’s symbol
have a _________.
Examples: N: __________ O: ________ F: ____________ Ne: ________
7. An element with an ___________ of valence electrons, such as a ___________ gas,
has a __________ configuration.
a. Octet rule: the tendency of ______________ atoms to have ____________ of
______________ electrons.
8. When 2 chlorine atoms form a _______________ bond, each atom contributes one
electron to form a _______________ pair.
a. With this _____________ pair, both atoms can have a _____________ octet.
b. Unshared pair: a non-bonding pair of ________________ in the valence shell of
an atom; also called a _____________ pair.
9. Single bond : a ______________ bond in which _________ atoms share __________
pair of electrons
a. The ______________ pair of electrons are replaced with a __________,
indicating a _____________ bond. (A dash counts for ________ electrons)
10. 5 Steps for Drawing Lewis Structures
1. Determine the number of valence electrons in each atom.
 Add them up to get the total number of valence electrons in the molecule.
2. Arrange the atoms
 Hydrogen atoms can only form 1 bond!
 Halogen atoms often bind to only one other atom and usually at the end of the
molecule.
 Carbon wants to be the center of attention and is often placed in the center of
the molecule. (Carbon is a DIVA!)
 With the exception of carbon, the atom with the lowest electronegativity is
often the central atom.
 Molecules also like to be symmetrical.
3. Distribute the dots (valence electrons)
 Arrange the dots so that each atom, except for hydrogen (2), beryllium (4), and
boron (6), satisfies the octet rule (8 dots around each atom).
4. Draw the bonds
 Change each pair of dots that represents a shared pair of electrons to a long
dash to represent a covalent bond.
5. Verify the structure!
 Count the number of electrons around each atom. Make sure the octet rule is
satisfied and that you have the correct number of dots that you determined in
Step 1.
11. Sample Problem A, pg. 202
a. Draw a Lewis structure for CH3I
12. Additional Examples
a. Draw a Lewis structure for SCl2
b. Draw a Lewis structure for AsF3
c. Draw a Lewis structure for SiH4
d. Draw a Lewis structure for CHF3
13. Lewis
a.
b.
c.
structures can be drawn for _______________ ions as well.
If the charge on the polyatomic ion is negative, you must ___________ electrons.
If the charge on the polyatomic ion is positive, you must ____________ electrons.
The entire Lewis structure is put in _______________ to show that the
__________ of the ion is distributed over all of the atoms.
14. Sample Problem B, pg. 203.
a. Draw a Lewis structure for the sulfate ion, SO4 2-
15. Additional Examples
a. OH –
b. NH4
+
c. H3O+
d. ClO-