Question

Which one of the following elements belongs to Group III A of the periodic table.

a) Mg b) K c) Al d) Si​

Answer 1

(C) Al belongs to Group III A of the periodic table.

How are elements arranged in periodic table?

• In modern periodic table, elements are arranged in increasing order of atomic number.
• Elements are arranged in horizontal rows called Periods and vertical columns called Groups.

Significance of Groups in periodic table:

• There are total 18 groups in the periodic table
• Groups are arranged based on the number of valence electrons of the elements.
• Elements with the same number of valence electrons will be placed under the same group.
• For example, group 2 and group 2A will have elements with 2 valence electrons (like Mg)

We can observe in this question that the electronic configuration of the elements are:

1. Magnesium Mg= $2, 8, 2$ (valence electrons = 2)
2. Potassium K = $2, 8, 8, 1$ (valence electrons = 1)
3. Aluminium Al= $2, 8, 3$ (valence electrons = 3)
4. Silicon Si = $2, 8, 4$ (valence electrons = 4)

We can see that only Aluminium (Al) has 3 electrons in its valence shell, so it will be placed in Group III A.

So, (C) Al belongs to Group III A of the periodic table.

Answer 2

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$(C) Al belongs to Group III A of the periodic table.</h3><h3></h3><h3>How are elements arranged in periodic table?</h3><h3></h3><h3>In modern periodic table, elements are arranged in increasing order of atomic number.</h3><h3></h3><h3>Elements are arranged in horizontal rows called Periods and vertical columns called Groups.8</h3><h3></h3><h3>Significance of Groups in periodic table:</h3><h3></h3><h3>There are total 18 groups in the periodic table</h3><h3></h3><h3>Groups are arranged based on the number of valence electrons of the elements.</h3><h3></h3><h3>Elements with the same number of valence electrons will be placed under the same group.</h3><h3></h3><h3>For example, group 2 and group 2A will have elements with 2 valence electrons (like Mg)</h3><h3></h3><h3>We can observe in this question that the electronic configuration of the elements are:</h3><h3></h3><h3>Magnesium Mg= 2, 8, 22,8,2 (valence electrons = 2)</h3><h3></h3><h3>Potassium K = 2, 8, 8, 12,8,8,1 (valence electrons = 1)</h3><h3></h3><h3>Aluminium Al= 2, 8, 32,8,3 (valence electrons = 3)</h3><h3></h3><h3>Silicon Si = 2, 8, 42,8,4 (valence electrons = 4)</h3><h3></h3><h3>We can see that only Aluminium (Al) has 3 electrons in its valence shell, so it will be placed in Group III A.</h3><h3></h3><h3>So, (C) Al belongs to Group III A of the periodic table.</h3><h3></h3><h3>$belongs to Group III A of the periodic table.

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