There are 7 main periodic properties of the periodic table which are mentioned below:
1- Atomic Radius and Atom size Properties of Periodic Table
The distance between the center of the nucleus of an atom from its last orbital is called the atomic radius. The size of an atom is determined only by the atomic radius. The greater the atomic radius of an atom the greater the atomic size of that atom.
a) Changes in the Atomic Radius in a Period of the Periodic Table
Moving from left to right in the periodic table as the atomic number of elements increases, the atomic radius decreases because increasing the atomic number increases the effective nuclear charge and its effect while the number of orbitals remains unchanged. This increases the nuclear attraction of electrons and draws electrons towards the nucleus.
Na > Mg > Al > Si > P > S > Cl
b) Changes in Atomic Radius in Groups
Increasing the atomic number as the groups move from top to bottom also increases the number of orbitals, increasing the atomic radius, which also increases the size of the atom.
Li < Na < K < Rb < Cs
The energy used to eject the electron farthest away from the nucleus of a deferred gaseous atom is called the ionization potential of that element.
a) Changes in Ionization Potentials in a Period of the periodic table
Decreasing the atomic radius when moving from left to right in the period increases the attraction force on the electron farthest from the nucleus, thus increasing the value of the energy required to take it out. Thus, ionization potential increases when moving from left to right in the periodic table. (Helium has the greatest ionization potential)
Li < B < Be < C < O < N < F
b) Changes in Ionization Potential in the Groups of the periodic table
As the atomic number increases more and more as the groups move from top to bottom, the value of atomic radius increases as a result of which the attraction force on the electron farthest from the nucleus decreases. Due to the value of ionization potential also decreases.
Li > Na > K > Rb > Cs
The energy that is emitted by a gaseous atom of an element to form an anion by taking electrons is called the electron affinity of that element.
a) Changes in the Electron Affinity in Periods
The atomic radius decreases as the atomic number increase from left to right in the period, increasing the attraction force on the orbit farthest from the nucleus, which causes another atom to come into contact with its final orbit. The transfer of electrons is simplified and the atom is converted to anion. Therefore, the electron bonding of elements increases when moving from left to right in a period.
Na < Mg < Al < Si < P < S < Cl
b) Changes in Electron Affinity in Groups
As the atomic radius increases from top to bottom in the groups, the attraction force on the orbitals farthest from the nucleus decreases, which reduces the ability to gain electrons from another atom in the outer one. Therefore, the electron affinity decreases when going from top to bottom in the groups.
H > Li > Na > K > Rb > Cs
4- Metallic or Electropositive Characteristics
Metals have a tendency to give up electrons and form cations. Therefore, the higher the tendency of an element to turn into cation, the higher its metallic characteristic or electropositive characteristic.
a) Changes in the Metallic Character in the Periods
Due to the decrease in the atomic radius in a period from left to right, the attraction force of the nucleus increases due to which the tendency of elements to abandon electrons and make cation decreases, that is, less of metallic or metallic properties. It happens.
b) Changes in the Metallic Character in the Groups
The size of the atom increases when moving from top to bottom in the groups, which reduces the nuclear attraction force and increases the tendency of cation to leave the electron. That is when moving from top to bottom in the groups, the metallic properties increase.
The change in non-metallic characteristics is the opposite of the change in metallic characteristics, that is, when moving from left to right in the period, the non-metallic properties increase and when moving from top to bottom in the groups, the non-metallic properties decrease.
5- Changes in the Tendency of Oxides
Generally, metal oxides are alkaline and nonmetal oxides are acidic, hence the acidic properties of oxides increase while going from left to right in a period while the alkaline properties decrease.
Na2O > MgO > Al2O3 > SiO2 > P2O5 > SO3
In contrast, the acidic property of oxides decreases when moving from top to bottom while the alkaline properties increase.
The ability of an atom to give up or accept an electron is called its valency. Moving from left to right in short periods, the hydrogen per valence of the elements first increases from 1 to 4, then decreases from 4 to 1 while the valence per oxygen increases from 1 to 7.
There is no change in valency in classes.
7- Changes in Density, Boiling Point, and Melting Point
All these properties increase from left to right in the period, increasing in the middle of the period and decreasing again.
There is no significant change in these properties in classes.