Question

Question 7
(a) Give a general idea of Dobernier triads with one example.
(b) State Mendeleev's Periodic Law and give its defects.
(c) An element X has atomic number 17 and has mass no. 37.
Draw its orbital structure and state the position of X in the periodic-table.
(d) (i) Write the molecular formula of magnesium phosphate.
(ii) Calculate the molecular mass of this compound.
(iii) What is the percentage of phosphorus in magnesium phosphate ?
[At. mass : Mg = 24, P = 31, 0 = 16]​

Answer 1

Answer:

Explanation:

a) Dobereiner triads: 3 elements following similar chemical and physical properties. Example: Li, Na, K

b) It stated that the properties of the elements are a periodic function of their atomic masses. It had a drawback like he was not able to find the location of the Hydrogen Atom. The atomic mass increase wasn't gradual due to isobars.

c) X = Chlorine (Cl) [for orbital: 2,8, 7]

d) i) Mg3(PO4)2

d) ii) 262 Units

d) iii) 23.7%