Silver, Gold, and More! Periodic Table Guide
The periodic table of chemical elements is an organized way for anybody to see the 118 known elements and
understand their properties. The periodic table includes the atomic mass and chemical symbol for each
element and may also include properties such as electronegativity, ionization energy, and atomic radius.
It can be confusing at first glance, but before 1869, it was even more confusing, as scientists worked
for years to determine what was the most effective way to organize the elements in a chart that would
help people understand them. Dmitri Mendeleev created the version of the periodic table currently used
today, though it has evolved over the past 150 years as we've developed a greater understanding of
chemistry and physics.
The Legend
For those new to learning about the periodic table, it's best to obtain a copy that has a
color-coordinated legend to help you learn the basics. The colors used may vary, but the categories are
the same on every table.
The Numbers and Letters
Every element is listed within its own block and is identified with letters and numbers. The letters are
the scientific abbreviations for each element. For example, "C" is carbon, "He" is helium, and "Ag" is
silver. The number above the letters is called the atomic number, and it's the number of protons in a
single atom of the element. The bottom number is the atomic mass; it represents the average weight of a
single atom of that element.
Groups
Every vertical column on the periodic table is a group. There are 18 groups on the periodic table, one
for every column. Elements in a group all have similar properties.
Periods
Since there is a vertical grouping of elements, it's important to note that there is a horizontal method
of grouping them as well. These are called periods, and elements in each period also share certain
properties. There are fewer periods in the table, only seven, compared to the 18 groups shown on the
periodic table.
Increasing Atomic Number
Elements in the periodic table are listed in order of their atomic number from smallest to largest.
Hydrogen is located in the top left of the periodic table with an atomic number of 1, and the numbers
increase from left to right and top to bottom.
Atomic Radius (Atom Size)
The atomic radius is the distance between the nuclei of two identical atoms of an element that have
bonded together. These measurements aren't often listed on the periodic table, but there's a trick to
figuring out which ones are larger or smaller. The atomic radii are ordered from smallest to largest
started at the top right and increasing from right to left and from top to bottom. This means that
helium, in its spot at the top right of the table, has the smallest atomic radius, and the element at
the bottom left, francium, has the largest atomic radius of the elements.