Advertisements
Advertisements
प्रश्न
How did the early chemists classify elements?
उत्तर
Early chemists classified the elements on the bases of their properties, nature, character, valency, and whether they were metals or non-metals.
APPEARS IN
संबंधित प्रश्न
Rewrite the following statement after correction, if necessary:
Periods are the horizontal rows of elements.
Why do we classify elements?
An element X from group 2 of the periodic table reacts with an element Y from group 17 to form a compound.
(a) What is the nature of the compound formed?
(b) State whether the compound formed will conduct electricity or not.
(c) Give the formula of the compound formed.
(d) What is the valency of element X?
(e) How many electrons are there in the outermost shell of an atom of element Y?
A non-metal X which is the largest constituent of air combines with hydrogen when heated in the presence of iron as catalyst to form a gas Y. When gas Y is treated with sulphuric acid, it forms a compound Z which is used as a chemical fertiliser.
(a) What are X, Y and Z?
(b) To which group of periodic table does X belong?
(c) Name the periodic table in which X is placed.
(d) Which element is placed just before X in the period?
(e) Which element is placed just after X in the period?
(a) How is possible valency of an element determined from the electronic configuration of its atom ?
(b) Determine the valency of an element X whose atomic number is 15.
Give a reason why elements need to be properly classified.
The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was ______.
Identify the bond between H and F in the HF molecules.
Consider the following elements 20Ca, 8Or 18Ar, 16S, 4Be, 2He
Which of the above elements would you expect to be in group 16 of the Periodic Table?
The element with atomic number 26 will be found in group ______
