# Periodic Table Classification

We use a great number of elements in our daily life without much knowledge of their properties. Efficient usage of these elements can be made with the knowledge of their properties. As there are more than hundred elements, it is hard to remember the properties of each and every element. So, is there an easy way to remember and understand the properties of elements?

Source: http://en.wikipedia.org/wiki/Periodic_table

A simple solution for this problem was given by a scientist Dmitri Mendeleev in 1869. He grouped all the elements with similar properties in the form of a table. This table was given the name periodic table. He organized elements in the order of increasing atomic weight. However, the periodic table we use today is not that proposed by Mendeleev. There is greater significance for atomic number and can be found by knowing the number of protons present in the atom. Basing on this fact Henry Moseley in 1914 reorganized the entire periodic table. He arranged elements in the increasing order of atomic number. It is the Moseley periodic table that we use today.

As said earlier, atoms are arranged in the periodic table in rows and columns. The vertical rows are called groups and the horizontal columns are called periods. There are 7 periods and 18 groups in a periodic table.

Periods: atomic number of the elements increases as you move from left to right. The number of elements in a particular period increases as you move down the periodic table. The period number signifies the highest energy level that can be attained by the elements in that period. As the number of energy levels increase as we move down the period there are more number of sub-levels available to accommodate more number of elements. Thus, the number of elements in a particular period increases as we move down the periodic table.

Groups: like periods, the atomic number of the elements in a particular group increases as we move from top to bottom. All the elements in a particular group have same outer electron configuration i.e. the valence electrons. Due to the presence of same number of valence electrons, all the elements in a group have similar properties. All the elements in a periodic table are arranged into two sets of groups they are Group A elements which are termed as representative elements and the Group B elements termed as non-representative elements.

As said, all the elements in a group have same outer electronic configuration. So, all the representative elements i.e. group A elements have s or p sublevels in the outer orbitals. The non-representative elements have partly filled d-orbitals or the partly filled f-orbitals. Elements with partly filled d-orbitals are termed as transition elements and those with partly filled f-orbitals are termed as lanthanides and actinidies.

The group number given on the top of the periodic table indicates the number of valence electrons in that group. For example, Group VA will have five electrons in the outer orbital. As all the A series elements have either s or p sublevels, we have s2 p3 as their outer configuration.

Solved problems
• What is period table that is being followed now-a-days?
• Mendeleev’s
• Moseley’s
• Both a and b
• Rutherford
• What is the basis for grouping of elements as per the Moseley’s periodic table?
• Atomic number
• Atomic mass
• Ionization energy
• What are vertical rows of a periodic table called?
• Periods
• Groups
• a or b
• None
• The outermost configuration of the elements of group IV A is
• SP
• S2 P3
• S2 P
• S2 P2