Chemistry Reference
In-Depth Information
(a) Because sulfur lies to the left of chlorine in the periodic table (in the
same period), sulfur is named first.
(b) Because sulfur lies below oxygen in the periodic table (in the same
group), sulfur is named first.
(c) Because sulfur lies to the left of iodine in the periodic table, sulfur is
named first (despite being above iodine).
(d) Even though oxygen lies to the left of chlorine in the periodic table,
chlorine is named first. Oxygen is an exception to the rule that a position
toward the left is more important than a position lower in the table.
(e) Even though oxygen lies to the left of xenon in the periodic table, xenon
is named first. (Oxygen is always named last except in its compounds
with fluorine.)
Practice Problem 6.1
Which element has its symbol written first in a
binary compound of each of the following pairs of elements?
(a)
F and Xe
(b)
O and F
(c)
O and N
To name a binary compound of two nonmetals,
• Name the first element.
• Use the root of the second element with the ending changed to -ide.
• In addition, add a
prefix
before each name to indicate the number of atoms
of each element. The prefixes are given in Table 6.1. However, if there is
only one atom of the
first
element, omit the prefix
mono-
for that element.
Also, if hydrogen is the first element, omit the prefix for
both
elements.
• When the name of the element starts with an
o
and the prefix ends in
a
or
o,
the
a
or
o
is usually dropped.
Figure 6.1
Household
Ammonia
A solution of (gaseous) ammonia in
water.
EXAMPLE 6.2
Table 6.1
Prefixes Used in
Naming Binary Nonmetal-
Nonmetal Compounds
Name the compound with formula containing (a) four atoms of chlorine and
one atom of silicon, (b) one atom of sulfur and three atoms of oxygen, (c) two
atoms of bromine and one atom of sulfur, (d) two atoms of phosphorus and
three atoms of sulfur.
Number
of Atoms
Prefix*
Solution
1
mon(o)-
(a) Silicon tetrachloride (Silicon is written first since it lies to the left of chlorine.)
(b) Sulfur trioxide (Sulfur is named first since it lies below oxygen.)
(c) Sulfur dibromide (Sulfur is written first since it lies left of bromine, even
though bromine is below it.)
(d) Diphosphorus trisulfide (The prefix
di-
is attached to the first element
since there is more than one atom of that element.)
2
di-
3
tri-
4
tetr(a)-
5
pent(a)-
6
hex(a)-
7
hept(a)-
8
oct(a)-
9
non(a)-
Practice Problem 6.2
Name the compound with formula containing
(a) two atoms of chlorine and three atoms of oxygen, (b) four atoms of sulfur
and four atoms of nitrogen, (c) two atoms of phosphorus and five atoms of sulfur,
(d) two atoms of fluorine and one atom of sulfur.
10
dec(a)-
*The last
o
or
a
of the prefix is usually
dropped when the element name begins
with
o.
