all questions are in the file CHM 113

Question 1
1.
Very few elements are found in their pure elemental form in nature. Most are
found combined in compounds. In this chapter we will take a closer look at the
nature of covalent (molecular) and ionic bonds, and also consider metallic bonds.

Question 2
1.
Valence electrons are found where in an electron configuration?

Question 3
1.
Lewis structures are a simplified way of showing the valence electrons of an
element. Look at Table 8.1, how many valence electrons does the element
magnesium have?

Question 4
1.
What is the Lewis Dot symbol of Mg?

Question 5
1.
Valence electrons are the electrons involved in chemical bonds. In general, the
number of electrons involved in bonds is described by the octet rule which states:

Question 6
1.
When an ionic compound is formed we depict it as a cation and anion coming
together. But this actually occurs via a _________________ of electrons between
the two.

Question 7
1.
Recall that an ionic solid is an extended network of atoms that we refer to as a
lattice structure. The strength of attraction between ions in this structure is call
the Lattice Energy, which is defined as:

Question 8
1.
The electron configuration for ions reflect the added or lost electron(s). Hint:
invariant ions go to the closest Noble gas configuration.
What is the electron configuration for the fluoride ion, F-?
What is the electron configuration for the magnesium ion, Mg2+?

Question 9
1.

Covalent bonds are found in molecules that are a combination of non-metals. In a
covalent bond the bond is formed by ________________ of electrons between
atoms.

Question 10
1.
The octet rule is generally (but not always) obeyed in the formation of covalent
bonds. We use Lewis Structures to depict the electrons being shared in covalent
bonds. When there are two dots between 2 elements it depicts a single bond,
when there are 4 dots it depicts a

bond and 6 dots depicts a

bond.

Question 11
1.
Not all atoms ‘play fair’ when joined in covalent bonds, some are ‘electron hogs’
and pull the electron density toward themselves. These elements have a high
electronegativity and if they are bound to an element with low electronegativity it
results in a polar bond. Look at Figure 8.7, in the covalent molecule LiF which
atom has high electronegativity?

Question 12
1.
Drawing Lewis Dot Diagrams for covalent molecules starts with finding the total
valence electrons in the molecule. Using Table 8.1 as a guide find the total
valence electrons in: (careful H has only one valence electron)
HCl
NH4+
O2
C2H6

Question 13
1.
Formal charge determination is useful when more than one potential Lewis Dot
structure exists, it will show the most stable form. We will look at this in class.

Question 14
1.
Look at the possible structures for the NO3- molecule at the top of page 310, these
are called resonance structures. Describe the difference between these 3 forms
of the structure:

Question 15
1.
The Octet Rule Broken!!
Some elements don’t behave by the octet rule when they are the central atom.
Reference pages 312 and 313, look at the structures for BF3 and PCl5. How many

valence electrons does B have?
(see a connection?)

Question 16
1.
Bond enthalpy is defined as:

How many valence electrons does P have ?