Q9 of 59 Page 1

An element 'X' belongs to 3rd period and group 16 of the Modern Periodic Table.

(a) Determine the number of valence electrons and the valency of 'X'.


(b) Molecular formula of the compound when 'X' reacts with hydrogen and write its electron dot structure.


(c) Name the element 'X' and state whether it is metallic or non-metallic.

(a) Given: Element belongs to 3rd period and group 16.


Since it belongs to period 3, therefore, it has 3 energy shells and as the group number is 16, means that it have 6 electrons present in valence shell.


The electronic configuration will be: 2, 8, 6


The valency of element is 2 as it needs only 2 more electrons to attain stable gas configuration.


(b) Molecular formula of the compound when it reacts with hydrogen can be calculated by cross multiplication of valencies:



Therefore, the compound will be H2X. The electron dot structure of the compound is as follows:



(c) The name of the element is Sulphur and is non-metallic.


More from this chapter

All 59 →
7

Write chemical equation of the reaction of ethanoic acid with the following:

(a) Sodium; (b) Sodium hydroxide; (c) Ethanol


Write the name of one main product of each reaction.

 8

An aldehyde as well as a ketone can be represented by the same molecular formula, say C3H60.Write their structures and name them. State the relation between the two in the language of science.

 10

An element 'X' has mass number 35 and number of neutrons 18. Write atomic number and electronic configuration of 'X'. Also write group number, period number and valency of 'X'.

 11

Define reproduction. How does it help in providing stability to the population of species?