Prabin Kalikote

The element that shows the characteristics or propertiesof both metals & non-metals is called metalloids.Any 3 examples are:

1. Silicon (Si)
2. Germanium (Ge)
3. Arsenic (As)
   

The electrons present in the outermost shell or valenceshell of an atom are called valence electrons.

In a period,valency increases up to the 4thgroupand decreases up to the 8th group and again increases.

The elements where the last electron enters in s-orbital arecalled s-block elements.
The elements where the last electron enters thep-orbital of the outermost shell are called p-blockelements.

The position of s-block elements is IA and IIA groups.
The position of p-block elements are from IIIB to IIBgroup in the periodic table

The horizontal rows of the periodic table where theelements are arranged according to their similarities anddifferences for their easy study are called periods.

The vertical columns where elements are arrangedfor the recognization of the properties and otherstudies are called groups.

The 14 elements from cerium te lawrencium after lutetiumare called lanthanides.
The elements from thorium to lawrencium afteractinium are called actinides.

These elements are placed at the bottom of the periodictable because of their similar properties. Lanthanides arerare metals whereas actinides are artificial radioactivemetals. They show similar properties to the transitionalelements. So, they are placed separatelybelow thetransitional elements in blocks of the modem periodictable.

In the modern periodic table, the physical & chemical propertiesof the elements are changed to the periodic function of theiratomic numbers instead of atomic weight which solvesthe problem with isotopes. All isotopes of some elementrepresented by thesame atomic number. All thegaps ofMendeleev's periodic table are filled by discovering newelements. The column for inert gases was developedand all groups have sub-groups. In thisway, the modernperiodic table removes all the demerits of...

Modern periodic rule states that, 'Thephysical and chemical properties of the elements are theperiodic function of their atomic number'.