Reading the Periodic Table
Once again, here is a link to view a full-size periodic table:
To see the periodic table, click here.
Once the window appears, roll your mouse over the elements to see their
specific information. You can also access the periodic table by going into
the SparkNotes reference section that resides at the top of every SparkNotes
page.
General Structure of the Periodic Table
As stated last
section, the periodic
table organizes the elements according to general patterns of similarity. Below is a very
small image of the periodic table. It is basically unreadable in terms of specific
information, but it allows us to easily look at the periodic tables structure general trends.
Figure 2.1: A very small periodic table
The vertical columns of the periodic table (marked by yellow stripes in
the figure) are called groups. The horizontal rows are called
periods. There are 18 groups and 7 periods. In discussing the
periodic table from here on out we will use the terms group and period.
Down a group means moving from top to bottom; across a period means
moving from left to right.
Reading the Periodic Table: Carbon
To describe the information contained within each individual box we will use a specific example: carbon.
Figure 2.2: Description of Carbon on the Periodic Table
Element Name
The purpose of the element name is obvious. However, many Periodic Tables do not include element names. For those situations you must memorize the symbols that accord to each element name.
Element Symbol
Each element has a specific one or two letter symbol that is used interchangeably with its name. These
should be memorized. Most of the time, symbols quite clearly accord to the name of the element they
represent, as C accords to carbon. Occasional, however, an element's name and symbol have little
relation. For example, the symbol for mercury is Hg.
Atomic Number
As you move across a period the atomic number increases. Similarly, as you move down a group the atomic number increases. In this way, the atomic number represents exactly where in the periodic table an element stands.
More importantly, and the reason why the ordering of the elements according to atomic
number yields elements in groups with similar chemical and physical properties, the
atomic number is the same as the number of
protons in the nucleus
of an atom of an element, and also the same as the number of
electrons surrounding
the nucleus in a neutral state. Carbon, for example, has six protons and six electrons.
(Protons and electrons will be discussed in more detail in the Atomic Structure
SparkNote)
(atomicmass)
Atomic Mass
Along with protons, an atom also contains neutrons in its nucleus. The atomic
mass
(also called atomic weight) of an element is the combined number of protons and neutrons
in the nucleus.
Atoms of particular elements generally have different "versions," meaning that elements
have atoms with different numbers of neutrons in their nucleus. These different versions
are called isotopes. The atomic weight displayed is actually the weighted average of
the mass numbers of the various isotopes. The atomic weight for Carbon is 12.01
because around 99% of all carbon is the carbon-12 isotope.
Atomic Number
The Atomic number increases from the top left to the bottom right. It
ascends sequentially across each period.
Atomic Weight
Weight
The atomic weight of the elements generally increases as you move down
a group and across a period. Hydrogen, at the top left of the table,
is the lightest element. The unnamed element 112 is the heaviest.
There are some instances when this rule does not hold true, however.
For instance, because it has a high percentage of isotopes with many
neutrons, the atomic weight of tellurium (Te) is higher than that for
iodine (I), even though iodine has a higher atomic number.
Types of Elements
Elements can be organized by group or period, but they also can be placed into three distinct groups:
metals, semi-metals, and non-metals.
Metals
Metals are the pink section on the left side of . Metals are generally
lustrous solids, often deformable (though mercury (Hg) is a liquid at room temperature). Metals are
highly conducive to both heat and electricity.
Nonmetals
Nonmetals are the blue boxes on the upper right hand of the periodic table. More than half of the
non-metals are gaseous at normal temperatures.
Semimetals
Semimetals are the green boxes on the periodic table. As their transitory name and placement on the
periodic table suggest, they exist in between the distinctions of metals and nonmetals.
Metals and Nonmetals
Most chemical compounds are formed by the interactions between metals and non-
metals.
Further Periodic Trends
Beyond those trends described here, there are a number of further periodic trends such as
atomic size, ionization
energy,
electron affinity, and
electronegativity. We
will discuss these trends in the atomic structure
SparkNote, since we must
have a better understanding of atomic structure before getting into their specifics.
