(a) What is Modern Periodic Law? (b) Atomic masses of nickel and cobalt are respectively 58.7 and 58.9. Which of them should appear first in the Periodic Table? (c) In which groups of the Periodic Table are the elements germanium and strontium present? (d) What is meant by the Law of Octaves? (e) Which has the bigger size:- (i) out of chlorine and bromine? (ii) out of sodium and magnesium?
Answers
Explanation:
(a)
The modern periodic law states that the properties of the elements are a periodic function of their atomic numbers. As the properties of the elements are dependent upon the atomic number we can say that these are dependent upon the electronic configuration of the elements.
(b) Atomic masses of Nickel and Cobalt are 58.7 and 58.9 respectively. Which of them should appear first in the Periodic Table? Why? cobalt must come first bcoz the elemets are arranged in order to their atomic number by mosley and not mass, and as the at no of cobalt is smaller it comes before nickel.
(c) Germanium is a chemical element with the symbol Ge and atomic number 32. It is a lustrous, hard-brittle, grayish-white metalloid in the carbon group, chemically similar to its group neighbours silicon and tin. Pure germanium is a semiconductor with an appearance similar to elemental silicon. Like silicon, germanium naturally reacts and forms complexes with oxygen in nature.
(d) Law of octaves, in chemistry, the generalization made by the English chemist J.A.R. Newlands in 1865 that, if the chemical elements are arranged according to increasing atomic weight, those with similar physical and chemical properties occur after each interval of seven elements.
(e) (I) Bromine is bigger in size than chlorine atomic radius increases from top to bottom as top to bottom no. of shells increases.
(II) Sodium(Na) is bigger than Magnesium(Mg) because the atomic no. of Na is 11 whereas the atomic number of Magnesium is 12 so the atom of Magnesium shrinks more than sodium