Question

Write down the electronic configuration of the following elements from the given atomic numbers. Answer the following question with explanation.
a. ₃Li, ₁₄He, ₁₁Na, ₁₅P Which of these elements belong to be period 3?
b. ₁H, ₇N, ₂₀Ca, ₁₆S, ₄Be, ₁₈Ar Which of these elements belong tot he second group?
c. ₇N, ₆C, ₈O, ₅B, ₁₃Al Which is the most electronegative element among these?
d. ₄Be, ₆C, ₈O, ₅B, ₁₃Al Which is the most electropositive element among these?
e. ₁₁Na, ₁₅P, ₁₇Cl, ₁₄Si, ₁₂Mg Which of these has largest atoms?
f. ₁₉K, ₃Li, ₁₁Na, ₄Be Which of these atoms has smallest atomic radius?
g. ₁₃Al, ₁₄Si, ₁₁Na, ₁₂Mg, ₁₆S Which of the above elements has the highest metallic character?
h. ₆C, ₃Li, ₉F, ₇N, ₈O Which of the above elements has the highest nonmetallic character?

Answer 1

a. ₃Li, ₁₄He, ₁₁Na, ₁₅P
Electronic configuration of the following elements is:
₃Li = 2,1
₁₄He =2,8,4
₁₁Na = 2,8,1
₁₅P = 2,8,5
₁₄He, ₁₁Na, ₁₅P belong to the third period because according to their electronic configuration, each element contains three shell i.e. K,L,M.

b. ₁H, ₇N, ₂₀Ca, ₁₆S, ₄Be, ₁₈Ar
Electronic configuration of the following elements is:
₁H = 1
₇N = 2,5
₂₀Ca = 2,8,8,2
₁₆S = 2,8,6
₄Be = 2,2
₁₈Ar = 2,8,8
₂₀Ca, ₄Be belong to second group because these elements have 2 electrons in its outermost shell.

c. ₇N, ₆C, ₈O, ₅B, ₁₃Al
Electronic configuration of the following elements is:
₇N =2,5
₆C = 2,4
₈O = 2,6
₅B = 2,3
₁₃Al = 2,8,3
₈O is the most electronegative element among these because electronegativity increases as we move from left to right in a period of the periodic table.

d. ₄Be, ₆C, ₈O, ₅B, ₁₃Al
Electronic configuration of the following elements is:
₄Be = 2,2
₆C = 2,4
₈O = 2,6
₅B = 2,3
₁₃Al = 2,8,3
₁₃Al is the most electropositive element among these because ₄Be, ₆C, ₈O, ₅B belong to same period, but ₁₃Al belong to next period. According to the trend, electropositive character of an elements increases as we move from top to bottom in a group of the periodic table. This happens as the tendency of an atom to lose electrons increases due to decrease in nuclear charge and increase in numbers of shell.

e. ₁₁Na, ₁₅P, ₁₇Cl, ₁₄Si, ₁₂Mg
Electronic configuration of the following elements is:
₁₁Na = 2,8,1
₁₅P = 2,8,5
₁₇Cl = 2,8,7
₁₄Si = 2,8,4
₁₂Mg = 2,8,2
₁₁Na has largest size among these because according to the trend, atomic radius decreases as we move from left to right in a period of the periodic table. The atomic number of elements increases which means the number of protons and electrons in the atoms increases. Due to large positive charge on the nucleus, the electrons are pulled closer to the nucleus and the size of atom decreases.

f. ₁₉K, ₃Li, ₁₁Na, ₄Be
Electronic configuration of the following elements is:
₁₉K = 2,8,8,1
₃Li = 2,1
₁₁Na = 2,8,1
₄Be = 2,2
₄Be has smallest atomic radius because ₁₉K, ₃Li, ₁₁Na are present in same group 1 but Be is present in group 2. According to the trend, as we move from left to right atomic size of an atoms decreases. Due to large positive charge on the nucleus, the electrons are pulled closer to the nucleus and the size of atom decreases.
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g. ₁₃Al, ₁₄Si, ₁₁Na, ₁₂Mg, ₁₆S
Electronic configuration of the following elements is:
3Al = 2,8,3
₁₄Si = 2,8,4
₁₁Na = 2,8,1
₁₂Mg = 2,8,2
₁₆S = 2,8,6
₁₁Na has the highest metallic character because metallic character of an elements decreases as we move from left to right in a modern periodic table. This happens as the tendency of an atom to lose electrons decreases due to gradual increase in the number of protons and nuclear charge.

h. ₆C, ₃Li, ₉F, ₇N, ₈O
Electronic configuration of the following elements is:
₆C = 2,4
₃Li = 2,1
₉F = 2,7
₇N = 2,5
₈O = 2,6
₉F has the highest nonmetallic character because non-metallic character of an elements increases as we move from left to right in a period of the periodic table. This happens as the tendency of an atom to gain electrons increases due to increase in nuclear charge, the valence electrons are pulled in strongly by the nucleus and it becomes easier for an atom to gain electrons.
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