The following data represents the distribution of electrons, protons and neutrons in the atoms of four elements A, B, C, D.
 
Elements Protons Neutrons Electrons
A
B
C
19
17
17
18
21
18
20
22
19
17
17
18

Answer the following questions.
a) Describe the electronic distribution in atom of element B.
b) Is element B a metal or a non-metal why?
c) Which two elements form a pair of Isotopes.
d) Which two elements form a pair of Isobars.
 

Dear Student,
a) The number of protons= number of electrons so the number of electrons in B is 17
So the electronic configuration will be 2,8,7 
Shell K has 2 electrons
Shell L has 8 electrons
Shell M has 7 electrons
b) Element B is a non-metal because it gains electrons to achieve stable octet.
c) Isotopes are atoms of same element having  atomic number but different mass number.
 that means same number of electrons but different number of neutrons
B and C are isotopes
d) Isobars are atoms of different elements having same number of nucleons (number of protons +number of neutrons)
A and D are isobars each having 40 nucleons
Regards!
 

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A IS POTTASIUM
B IS CHLORINE
C IS ISOTOPE OF CHLORINE

D IS ARGON
 
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2,8,7 non metal C17 C18
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Isobars = A , C element isobars means different element but same atomic masss so add protrons and nutrons ti get atomic masss
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Ans i) 2, 8, 7 because protons= electrons
Ans ii) Element B is non-metal because non-metal takes electrons from metals.
Ans iii) Element B and C are the Isotopes
Ans iv) Element A and D are the Isobars
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