Calculate the atomic number of an element whose mass number is 31 and number of neutrons is 13. What is the symbol of the element?

Atomic number of X = Mass number of X – Number of neutrons         = 35–18=17  Electronic configuration = 2, 8, 7  Group number = Valence electrons +10 = 17  Period =...

Atomic number of X = Mass number of X – No. of neutrons =35 18=17 Electronic configuration = 2, 8, 7 Group number = 17 , Period No. = 3

Let protons = x Mass number = P+n Then neutrons= x + 31.7% of x 81= x + 1.317x X=35 Symbol= Br

Z=19   1s2 ,2s2 ,2p6 ,3s2 ,3p6 ,4s1     P-4th,       G-1st Z=35   1s2 ,2s2 ,2p6 ,3s2 ,3p6 ,4s2 ,3d10,4p5 .  P-4th,        G-17th

In a neutral atom, number of electrons are equal to the number of proton. No. of protons = No. of electrons = 29 Mass number = No. of protons + No. of...

Position of P Group-2 Because it has 2 valence electrons/ 2, S, 8, 2 Period-4 Because it has 4 shells/2,8,8,2 Position of Q Croup-17 Because it has 7 valence electrons/ 2, 8, 7 Period-3 Because it has 3 shells/...

Radius of Y is bigger than that of X.   In 'X' the number of shells is three while in Y it is four.

Atomic number of X = Mass number of X - No of neutrons =35-18=17 Therefore, Electronic configuration of  X=2,8,7 Croup number =17 Period = 3 Valency=8-7=1

(i) The position of elements X in the modern periodic table is group number 17 and period number 3. The position of element Y in the modern periodic table is...

(b) electrostatic force between protons are repulsive.