question_answer

  Given alongside is the atomic structure of an atom of element A, according to Bohr's model of atom. (i) What is wrong with this structure of atom? (ii) Draw a correct representation of this atom. (iii) Write the chemical formula of the chloride of this element. 

Answer:

   (i) Na has three shells K, L and M but here only 2 shell are given. Further L shell cannot have more than 8 electrons but here 9 electrons are given.                                  (ii) The correct structure is (iii) As Na has 1 valence electrons, thus it has a valency of +1 and chlorine has a valency of-1 Hence, the formula of its chloride is AC1.  (a) Nucleus                               (b) Oxygen and calcium                  (c)  

Element	Atomic number	Proton	Electron	Neutron	Mass number
A B C	17 14 9	17 14 9	17 14 9	18 14 19-9=10	17+18=35 14+14=28 19

 (a) Y will lose (2) electrons and X will gain  electrons.                                     (b) The number of electrons lost, gained or shared by an atom is called its valency.                 (c) Electronic configuration of X (Atomic no.  = 2, 8, 7 Electronic configuration of Y (Atomic no. 12) = 2,8,2                                    (a) Atomic size is represented in terms of atomic radius. Hence, the ratio of nucleus to atomic size =1:105                                   (b) If atomic size = 6.4 x 106 m Then, let the size of the nucleus be x m. According to the ratio given above,                  Thus, size of the nucleus  auld be 64 m.         (a)

Particles	Atomic number	Mass number
A B C D	3 9 8 9	3 = 4 =7 9 + 8 = 17 8 + 8 = 16 8 + 10 = 18

(b) Particles C and D as they have same number of protons i.e., atomic number but different mass number.                                      (a) A and B are isobars as they are atoms of different elements having the same mass number. X and Y are isotopes as they are atoms of same element (same atomic number) having different mass numbers.                          (b) No, these do not have identical chemical properties because they have different atomic numbers as well as electronic configurations,