Question

An element belongs to the 3rd period and group 1 of the periodic table.

1. Find out the number of valence electrons in its atom.
2. Valency of the element.
3. Metal or non-metal.
4. Name of the element.
5. Name of the family to which element belongs.

Answer 1

Modern periodic table:

• The modern periodic table is an arrangement of all the elements known in accordance with their increasing atomic number and recurring chemical properties.
• It is a tabular display of 118 chemical elements which consists of horizontal rows called periods and vertical columns called groups.
• All elements in a group have the same number of valance electrons, and in period elements have the same number of electron shells.
• There are seven periods and eighteen groups in the modern periodic table.

The element belongs to the 3rd period and group 1 of the periodic table is Sodium (Na) having atomic number 11.

(1) Valance Electrons:

• “Electrons in the outer shells that are not filled are called valence electrons”.
• These are the number of electrons an atom must lose or gain to attain the nearest noble gas electronic configuration.
• The electronic configuration is the arrangement of electrons in energy levels around an atomic nucleus.
• It can be written in K, L, M, and N format. Where the K, L, M, and N shells represent the energy shells.
• The total number of an electron in the shell is given by the formula 2N², where n is the shell number.
• For the K shell, the maximum number of electrons that can be acquired is 2, the L shell's maximum number of electrons that can be acquired is 8, and so on.

Since the element belongs to the 3rd period and group 1 of the periodic table is Sodium (Na) having atomic number 11 so its Electronic configuration is :

Na(11) = 2,8,1.

So the valance electrons, in this case, are 1.

(2) Valency of the element:

• The combining capacity of an atom is known as its valency.
• the total number of electrons lost, gained, or shared to complete its octet determines the valency of the atom.
• An atom’s valency is equal to the number of electrons in the outer shell when that number is four or fewer.
• If the valance electrons are more than four then the valency is equal to eight minus the number of electrons.

So in the case of sodium having Electronic configuration 2,8,1, its valency would be +1.

(3) Metal or non-metal:

• The metallic character is the tendency of an element to lose electrons and form positive ions or cations.
• The elements which have a tendency to gain electrons are known as non-metals.

Since sodium has a valency of +1 means it is losing one electron to acquire the Nobel gas configuration therefore it is a metal.

(4) Name of the element:

• The name of the element is Sodium.
• It is a chemical element with the symbol Na and atomic number 11.
• It is a soft, silvery-white, highly reactive metal.

(5) Name of the family to which element belongs:

• The s-block elements having only one electron in their s-orbital are called group one or alkali metals.
• The alkali metals consist of the chemical elements: Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), and Francium (Fr).
• Alkali metals are the most electropositive elements.