Question

Answer questions number 3(a)-3(d) on the basis of your understanding of the following paragraph and the related studied concepts.
Atoms of eight elements A, B, C, D, E, F, G and H have the same number of electron shells but different numbers of electrons in their outermost shells. It was found that elements A and G combine to form an ionic compound. This ionic compound is added in small amounts to almost all vegetables and dishes during cooking. Oxides of elements A and B are basic in nature while those elements E and F are acidic. The oxide of element D is, however, almost neutral. Based on the above information, answer the following question:
a.To which group or period of the periodic table do these elements belong?
b.What would be the nature of compounds formed by a combination of element B and F?
c.Which two of these elements could definitely be metals and which would be non-metals?
d.Which one of the eight elements is most likely to be found in gaseous state at room temperature?

Answer 1

To find the answers of the above asked questions, read the paragraph thoroughly. This will help you to figure out the group as well as the period they belong to. There are many hints provided in the paragraph which will help you to decode the answer.

Complete answer:
a.In a third period the elements are added to the $3s$ orbitals. Successive filling occurs at $3p$ orbitals. It begins with sodium to argon. They have the same number of electron shells but different numbers of electrons in their outermost shells. The number of valence electrons in these elements increases from $1 - 8$ as we move from left to right across the period.
They belong to the group $1$ (alkali metals), group $2$ (alkaline metals) and group $13$ to group $18$ . These are together called representative or main group elements.
b.As B and F belong to the group $2$ and $16$ respectively they are metals and non-metals. When a metal and non-metal exchange electrons it results in formation of ionic bonds. So the compound will be ionic in nature. As when B’s basic oxide and F’s acidic oxide combine, it will result in ionic bond formation.
c.As mentioned earlier, A and B belong to the group $1$ and group $2$ , which are alkali metals and alkaline metals respectively, therefore A and B are definitely metals. Whereas the elements E, F and G are which belong to the group $13$ , $14$ and $15$ they are non-metals.
d.The elements of group $18$ are noble gas elements which are gaseous in state. Therefore element H is most likely to be found in the gaseous state at room temperature.

Note:
To answer such questions or questions related to the periodic table one must be familiar with the trends of groups and periods like their electronic configuration, their physical properties, valence or oxidation state etc. This helps in predicting the reactant as well as their behavior.