Read Section 3.8 before viewing the slide show.
Unit 13
Electrons and their Relationship to the
Periodic Table
•Basic Periodic Table Nomenclature
•Identify Valence Electrons from the Periodic Table
•Identify Named Groupings of Elements on the
Periodic Table
Basic Periodic Table Nomenclature
•Rows are called periods.
Periods are numbered
from 1 at the top to 7.
•Columns are called
groups or families. The
currently adopted numbering system is to start with 1
at the first group on the left and number through 18
on the right. Older systems are still used that place
Roman numerals at the top of each group, but we will
stick with the newer version.
Period Number:
Electron Configurations from the Periodic Table
Group Numbers
1
2
3
4
5
6
7
Electron Configurations Related to
Periodic Table
•Electron configurations for elements in the same group have some
similarity – the shell number increases by 1 for each row down the
periodic table and the outer electrons are in the same subshell.
•For example, consider the first four elements of Group 1:
Element
# electrons
Electron Configuration
H
1
1s1
Li
3
1s22s1
Na
11
1s22s22p63s1
K
19
1s22s22p63s23p64s1
•Notice how each electron configuration ends in ns1 where n is the
shell number. The electrons in the highest numbered shell are
called the valence electrons. All elements in the same group have
the same number of valence electrons – in this case 1 valence
electron.
Valence Electrons and Group Number
•Because of the relationship between electron configuration
and group number, members of the same group have the
same number of valence electrons.
•The number of valence electrons in a group is equal to the
last digit in the group number.
•For example:
•Phosphorous (Z=15) is in Group 15 and has 5 valence electrons
•Strontium (Z=38) is in Group 2 and has 2 valence electrons
•Gallium (Z=31) is in Group 3 and has 3 valence electrons
•The above rule applies well for elements in Groups 1-2 and
13-18. The others become a little more problematic.
Named Regions of the Periodic Chart
•As may be expected, over
time names have been
assigned to regions of the
periodic table.
•Representative or Main
Group elements (Groups 1-2
and 13-18, blue border on the
chart to the right)
•Transition Elements (Groups
3 – 12, red on the chart above)
•Inner Transition Elements (Below the main framework of the chart,
green on the chart above)
More Named Regions
•Some groups are given special
names as well. Remember that
elements in the same group have
similar properties so it is
reasonable to name groups for
easy reference
•Alkali Metals – Group 1 (blue on
this chart)
•Alkaline Earth Metals – Group 2
(red on this chart)
•Chalcogens – Group 16 (green on this chart)
•Halogens – Group 17 (yellow on this chart)
•Noble gases – Group 18 (orange on this chart)
Metals and Nonmetals
•One more important
classification is metals and
nonmetals. We will make
decisions about types of
compounds, formula
writing, and nomenclature
based to a large extent on
this criterion.
•Metals – those elements to the
left of the stair-stepped line indicated on
the chart to the right
•Nonmetals - those elements to the left of the stair-stepped line (blue on
the above chart) indicated on the chart above
•Metals tend to conduct electricity and heat well, are malleable (can
be shaped by pounding), and are ductile (can be drawn).
Nonmetals typically do not have these properties.