Q41 of 52 Page 43

Properties of the elements are given below. Where would you locate the following elements in the periodic table?

(a) A soft metal stored under kerosene.


(b) An element with variable (more than one) valency stored under water.


(c) An element which is tetravalent and forms the basis of organic chemistry.


(d) An element which is an inert gas with atomic number 2.


(e) An element whose thin oxide layer is used to make other elements corrosion resistant by the process of “anodising”.

(a) Sodium (Na) – Group 1 and Period 3 or Potassium (K) – Group 1 and Period 4. Sodium and potassium are alkali metals. Such metals have high reactivity, hence they are usually kept under kerosene. Alkali metals are placed in group 1 and starts from period 2 to 7.


(b) Phosphorus (P) Group 15 and Period 3. It has a variable valency of 3 and 5. It reacts with air and not water. Thus, it is stored in water. It is placed in group 15 and period 3 of periodic table.


(c) Carbon (C) Group 14 and Period 2. Carbon forms the basis of all organic compounds. It is tetravalent because it has 4 valence electrons. It is placed in group 14 and period 2 of Periodic table.


(d) Helium (He) – Group 18 and Period 1. Helium is the lightest inert gas. It has atomic number 2. It is placed in group 18 and period 1 of periodic table.


(e) Aluminium (Al) – Group 13 and Period 3. Aluminium is used to make other elements corrosion resistant by the process of “anodising”. The oxide layer formed is that of Al2O3. . The atomic number of aluminum is 13 and it is placed in group 13 and period 3 of periodic table.


More from this chapter

All 52 →
39

Arrange the following elements in the increasing order of their metallic character Mg, Ca, K, Ge, Ga

 40

Identify the elements with the following property and arrange them in increasing order of their reactivity.

(a) An element which is a soft and reactive metal.


(b) The metal which is an important constituent of limestone.


(c) The metal which exists in liquid state at room temperature.

 42

An element is placed in 2nd Group and 3rd Period of the Periodic Table, burns in presence of oxygen to form a basic oxide.

(a) Identify the element.


(b) Write the electronic configuration.


(c) Write the balanced equation when it burns in the presence of air.


(d) Write a balanced equation when this oxide is dissolved in water.


(e) Draw the electron dot structure for the formation of this oxide.

 43

An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a divalent halide.

(a) Where in the periodic table are elements X and Y placed?


(b) Classify X and Y as metal (s), non-metal (s) or metalloid (s).


(c) What will be the nature of oxide of element Y? Identify the nature of bonding in the compound formed.


(d) Draw the electron dot structure of the divalent halide.