CBSE chemistry IX atomic structure

1.         What is an orbit, shell or energy level?  

2.         What is the maximum capacity of outermost shell of an atom?

3.         How does a proton differ from an electron?

4.         Name the particles which actually determine the mass of an atom.

5.         What are the symbols used to represent different orbits? Arrange them in order of energy?

6.         What are isobars? Give one example.

7.         Give any three important applications of isotopes.

8.         State the number of electrons present in the outermost shell of the atoms of the following elements:

            (i)    Neon                    (ii)    Chlorine

9.         From the symbol , state:

            (i)     Mass number of phosphorus,

            (ii)    Atomic number of phosphorus, and

            (iii)   Electron configuration of phosphorus.   

10.       The atomic number of an element X is 16.

            (a)   Write down the electronic configuration of X.

            (b)   What will be the valency of X?

11.       Natural chlorine contains chlorine in the form of the isotope ³⁵Cl (75.5%) and ³⁷Cl (24.5%). Calculate the average atomic mass of natural chlorine.

12.       (a)   Which fundamental particle is equal in number in Mg²⁺ and Al³⁺ ions?

            (b)   Atomic numbers of nitrogen and oxygen are 7 and 8, respectively. Calculate the total number of electrons in nitrate (NO₃^–) ion.

13.       The nuclear composition of two atomic species X and Y is as follows:

            X: 17 protons; 18 neutrons

            Y: 17 protons; 20 neutrons

            What are their (i) atomic numbers (ii) mass numbers? What is the relation between these two atomic species? Name the element or elements which they represent.

14.       What valencies will be shown by the elements A, B, C, D and E having atomic numbers 2, 4, 8, 10 and 13 respectively?   

15.       (a)   An element has an atomic number 12 and an atomic mass number 26. Draw a diagram showing the distribution of electron in the orbits and the nuclear composition of the neutral atom of the element. What is the valency of the element and why is it so?

            (b)   Explain the structures of the following atoms giving diagrams:

                     and

16.       (a)   What was the drawback of Rutherford’s model of atom?

            (b)   Describe Rutherford’s a-ray scattering experiment and mention the observations derived from it. Cite one defect of Rutherford’s model of the atom.