Series: Periodic Classification of Elements
The oxides of metals are basic, while those of non-metals are acidic. On moving from the left to the right in a period, the metallic character of the elements decreases, while the non-metallic character increases. The nature of the oxides of metals is basic, while that of non-metals is acidic. Show Less
The atomic size of an atom is the distance between the centre of its nucleus and its outermost electron shell. As we move down in a group, the atomic size of the elements increases gradually.
The chemical reactivity of metals increases from the top to the bottom in a group, while the chemical reactivity of non - metals decreases as we move down in the group. On moving down in a group of the Periodic Table, there is no change in the nature of the oxides of the elements. Show Less
The groups in the Periodic Table are arranged vertically. There are 18 groups in the Periodic Table. All the elements in one group have the same electronic configuration and hence the same number of valence electrons and the same valency.
The atomic size of an atom is the distance between the centre of its nucleus and its outermost electron shell. In the Periodic Table, on moving from the left to the right in a period, the atomic size and metallic character of the atoms decreases while, the non-metallic character increases. Show Less
The chemical reactivity of an element depends upon the position of the element in the Periodic Table and the electronic configuration of the element. On moving from the left to the right in a period, the chemical reactivity of the elements first decreases and then increases. Show Less
The horizontal rows of the elements in a Periodic Table are known as periods. There are seven periods in the Periodic Table. On moving from the left to the right in a period, the number of valence electrons in the elements increases from one to eight. Show Less
The valency of an element is determined by the number of valence electrons present in its atom. The valency of the element is calculated by the number of electrons lost or gained by its atom to achieve the nearest inert gas electron configuration.
Mendeleev’s Periodic Law states that the properties of elements are a periodic function of their atomic masses. The limitations of Mendeleev’s classification were that it could not explain the position of isotopes and the correct position was not assigned to hydrogen. Show Less
The modern periodic law states that properties of elements are the periodic function of their atomic numbers. The atomic number is equal to the number of electrons; it helps in arranging elements according to their electronic configuration, which is the present base of classification. Show Less
The elements in the Periodic Table are roughly divided into metals, metalloids and non-metals. There are seven periods in the Periodic Table. The vertical columns in a Periodic Table are called groups and there are 18 groups in the Periodic Table.