Which of the following is the most reactive halogen?
F
Cl
Br
I
Which of the following is the most reactive halogen?
F
Cl
Br
I
The correct option is A F
Halogens
Elements of group 17 are called halogens. These elements are highly electronegative and readily accepts electron to form stable octet configuration. All the halogens are non metals. The elements in the halogen group are Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At).
All the halogens are highly reactive due to the high effective nuclear charge which increases their electronegativity. The electronegativity of halogen therefore, depends on its size and therefore, decreases in the order:
Fluorine > Chlorine > Bromine > Iodine.
The number of valence electrons on halogen is seven. Therefore, it accepts one electron and becomes stable.
Explanations for wrong answer
(B) The electronegativity of Chlorine is less than Fluorine. Therefore, its reactivity is less than reactivity of fluorine. Option (B) is incorrect.
(C) The electronegativity of Bromine is less than that of Fluorine and Chlorine. Therefore, Its reactivity is lower. Option (C) is incorrect.
(D) Iodine has the lowest electronegativity among stable halogens. Therefore, the reactivity of Iodine will also be lowest. Option (D) is incorrect.
Explanation for correct answer
(A) The size of an atom decreases across a period and increases along a group. Therefore, halogens will have the smallest size among other elements in their respective period. Among halogens, the smallest atom is of Fluorine. Due to the small size of Fluorine, the effective nuclear charge in the atom will be very high. This makes the atom highly reactive. Therefore, Fluorine is the most reactive among halogens.
The correct option is (A) F
F
Halogens
Elements of group 17 are called halogens. These elements are highly electronegative and readily accepts electron to form stable octet configuration. All the halogens are non metals. The elements in the halogen group are Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At).
All the halogens are highly reactive due to the high effective nuclear charge which increases their electronegativity. The electronegativity of halogen therefore, depends on its size and therefore, decreases in the order:
Fluorine > Chlorine > Bromine > Iodine.
The number of valence electrons on halogen is seven. Therefore, it accepts one electron and becomes stable.
Explanations for wrong answer
(B) The electronegativity of Chlorine is less than Fluorine. Therefore, its reactivity is less than reactivity of fluorine. Option (B) is incorrect.
(C) The electronegativity of Bromine is less than that of Fluorine and Chlorine. Therefore, Its reactivity is lower. Option (C) is incorrect.
(D) Iodine has the lowest electronegativity among stable halogens. Therefore, the reactivity of Iodine will also be lowest. Option (D) is incorrect.
Explanation for correct answer
(A) The size of an atom decreases across a period and increases along a group. Therefore, halogens will have the smallest size among other elements in their respective period. Among halogens, the smallest atom is of Fluorine. Due to the small size of Fluorine, the effective nuclear charge in the atom will be very high. This makes the atom highly reactive. Therefore, Fluorine is the most reactive among halogens.
The correct option is (A) F
