Periodic table of elements

Periodic table trends of some fundamental properties of atoms and molecules largely understandable in terms of the outer electron configuration of the elements. Therefore we need a general survey of the major trends which given the details chemistry of elements by group or period.

Therefore the works of Mosely in 1911 provided a periodic law bases on the properties to formulate a modern form of the periodic table.

This law states as the properties of chemical elements and their compounds are the periodic functions of the atomic number.

Periodic table of elements trends

Types of elements on the periodic table

When the classification based on the electron configuration, the elements are divided into four type

  1. s-block
  2. p-block
  3. d-block
  4. f-block elements

s-block elements in the periodic table

In these elements, electron enters the ns-orbital and filled progressively. The elements of group-1 and group-2 belong to this group. Thus the valence shell electron configuration of these elements

where n = number of valence shell or number of period.

p-block elements in the periodic table

The elements in which p-orbitals being progressively filled are called p-block elements. Therefore the elements of group-3, 4, 5, 6, 7, and noble gases belong to this block.

Since s-orbitals in these atoms are already filled and the valence shell electron configuration

ns2 np1→6
where n = number of period.

d-block elements in the periodic table

When the electron enters the (n-1)d orbitals of (n-1)th main shell are called d-block elements. These placed in the middle of the periodic table between s and p-block elements.

These elements form an ionic or covalent chemical bond with other elements. Therefore these are called transition elements. The valence shell electronic configuration of these elements

ns0→2 nd1-10

Properties of elements in groups and periods

Ionization energy, electron affinity, and electronegativity are very important for any discussion of variation in chemical properties. Thus the fundamental trends apparent from the periodic table discuss in

Here we can summarize some properties along a period and a group.

Trends of the periodic properties of elements

  1. When we defending down a group, the size of an atom and its electropositive character increases.
  2. The ionization energy usually decreases but may increases when an effective nuclear charge actually increases for the lower member like Ag, Au, Cd, and Hg.
  3. Similarly, electronegativity and electron affinity generally decreases but sometimes apparent some anomalies. The electron affinity of the second raw element is usually lower than the third row.

Diagonal relationship in the periodic table

Li Be B C
Na Mg Al Si

The chemical properties of a pair of elements are related diagonally to each other.

Thus if we consider the polarization power of a cation. The polarizing power of cation depends directly on its change but inversely on its size.

Therefore we can expect the diagonal elements pair has a similar change/size ratio. Since the size increases to the lower period while the charge increases to the right. But this relation can not be ruled out completely.

This relationship loses for elements on the right side of the periodic table when the metallic character is practically absent.

Electronic Structure

Acids and Bases