What is the Periodic Table? | General Chemistry 1

What is a Simple Definition of the Periodic Table?

The periodic table can most simply be described as a chart that organizes the chemical elements of matter into an easy-to-identify visual flow chart. 

Why is it Called the Periodic Table?

The periodic table is called the "Periodic Table" because it's organized into periods and groups. These two categories go from left to right across horizontal rows (known as a period), and up & down within vertical columns (known as a group).

How is it Arranged?

It is organized by atomic number with hydrogen being number 1, helium being number 2, etc. It is also ordered by element block according to electron shell configuration. Each row of elements in the periodic table is called a period, and the elements are grouped according to the fill of electrons in their valence shells.

At the right of the table is a group that contains inert gases; elements with full valence shells and which are generally unreactive. At the left of the table is a group that contains reactive metals, such as sodium and potassium. The groups between these two columns are  alkaline-earth metals, transition metal groups, inner transition metal groups, non-metal groups, halogens. All the elements of these groups have their own properties and reactivities.

Color coding can be used to distinguish between columns (groups). And each element is represented by a symbol which is usually one or two letters taken from the name.

When Was It Discovered?

The periodic table was first published by Dimitri Mendeleev in 1869. He had been experimenting with organizing the elements according to their chemical properties and eventually noticed that certain trends existed within groups of elements. Not only did he come up with the organization of them, but he also predicted the existence of many elements before they were discovered.

What Does it Look Like?

The form of the table that is most familiar to us today is usually referred to as the short-form periodic table, or the common (or standard) form of the table. It is a rectangular grid of the elements, with periods going across and families going down. In addition to what is shown in most chemistry classrooms, there are some additional rows given for unstable elements called transactinides which have been created in laboratories but not found in nature.

List of Elements in the Periodic Table

How Many Element Blocks Are There?

There are 4 blocks that group elements together. They are often color-coded in visual representations. Each color corresponds to a single block group as well as one of the letters S, P, D, or F. 

S= Sharp

S is the symbol for s-block which contains elements from the first 2 columns and the helium. Their general valence configuration is ns¹ or ns²:

• Hydrogen (H)
• Helium (He)
• Lithium (Li)
• Beryllium (Be)
• Sodium (Na)
• Magnesium (Mg)
• Potassium (K)
• Calcium (Ca)
• Rubidium (Rb)
• Strontium (Sr)
• Cesium (Cs)
• Barium (Ba)
• Francium (Fr)
• Radium (Ra)

P= Principal

P stands for p-block, which contains elements whose properties often include nonmetals. Their general valence configuration is ns² np^1-6:

D= Diffuse

D symbolizes the d-block, which includes transition metals. The outermost layer, or shell, is called “n-1.” Within the d-block, there are four more series: 3d, 4d, 5d, or 6d orbitals. 6d is incomplete.

F= Fundamental

Finally, F represents the f-block, which includes inner transition metals. They also include some very reactive elements:

What is G-Block in the Periodic Table?

The g-block is a hypothetical region in the extended periodic table.  It is based on the various extra dimensions predicted by string theory. If this theory proves to be accurate, then the next row in the periodic table would start with element 121. 

How Many Elements Are Classified by the IUPAC?

As of 2021, there are 118 elements classified by the IUPAC. However, only 94 of these elements are naturally occurring. 

Step-by-Step: How to Read the Periodic Table

What Can You Tell About an Element Based on its Row?

Periods (Rows) - Read from left to right

Just as you would do with a book, the periodic table reads from the top left corner to the bottom right corner. The order of the periodic table is determined by atomic numbers, which increase as you move across and down from lighter to heavier elements. The atomic number tells us how many protons are in the atom of that element. 

What is the Relationship Between Atomic Number and the Position of an Element?
The table's organization helps us identify certain properties of the elements quickly just by looking at the table. Each consecutive element has one more proton than the previous. However, because the elements are also organized by group, gaps appear in the table. For example, the first row of the periodic table contains Hydrogen (1) and Helium (2), but they are at opposite ends because they both belong to different groups, despite only having a difference of one proton.

What Can We Tell From the Column That an Element is in?

Groups (Columns) - Read from top to bottom

Sometimes also referred to as 'families', elemental groups share certain physical and chemical properties. They are represented on the columns of the table. The vertical placement of the elements in a group indicates that they all have the same valence electron configurations.

In general, the metals are located on the left side, while nonmetals are located on the right side. This is because metals tend to lose electrons when bonding with other elements, whereas nonmetals tend to gain electrons when bonding.

Importance of Classifying Elements by Groups

The periodic table is one of the most basic and fundamental concepts in chemistry. It shows how chemical elements are related to each other through their chemical properties, as well as how the elements are organized according to those properties. The table itself has undergone many revisions and extensions since it was first published. There are now several variations such as the long-form and short-form periodic tables.