Fluorine is the most reactive nonmetal because it has the highest value of electronegativity. Reactivity of nonmetals is directly proportional to electronegativity. Having the electronegativity of 4, it has the highest ability to attract the shared pair of electron towards itself. As its ability to attract the shared pair of electron towards itself is more than any other element, fluorine is said to be the most reactive nonmetal in the periodic table.
This was a short and straight answer. If you want to get into some depth of this topic then this article is for you.
Let’s keep things simple. Reactivity is the ability of an element to react and form a bond with another element. The more reactive elements react easily without requiring high amount of energy. On the other hand, less reactive elements don’t react readily with other elements. They require some energy to form bond.
Just like any other property, reactivity also depends on another property. The basis of reactivity is different for metals and non metals. Since metals lose electrons, their reactivity depends on their electropositivity (ability to lose electrons). It has a direct relation with electropositivity.
But we know that nonmetals do not lose electrons they accept it. So we cannot measure their reactivity on the basis of electropositivity because their behavior is completely different from metals. It’s just like comparing the ability of a bird to fly with a fish. So we have another term for nonmetals and that is “electronegativity”.
The ability of an element to attract the shared pair of electron towards itself is known as electronegativity. It’s just an ability so it doesn’t have any unit. It’s minimum value is 0.7 assigned to Cesium metal. Maximum value is 4 assigned to fluorine. All the other elements lie between this scale and it is known as Pauling’s scale of electronegativity.
It also has a direct relation. The more electronegative nonmetals will be more reactive. Likewise less electronegative nonmetals will show less reactivity. But, why? Let’s understand it better. Reactivity is ability of bond formation. For nonmetals bond is formed when they accept electrons from other elements. If their ability to attract the shared pair of electron is less, how will they accept electrons? So for bond formation nonmetals have to accept electrons and to accept electrons they need to attract them so they require high electronegativity to be reactive.
If you move upward to downward in any group of periodic table you will see that electronegativity decrease down the group. While moving left to right in any period you will notice that electronegativity of elements is gradually increasing. Let’s now see the trend of reactivity for nonmetals. As we have discussed the reactivity has a direct relation with electronegativity. So the above trend is same for reactivity of nonmetals. Left to right it increases and top to bottom it decreases.
If we look to the trend of reactivity it tells us that the most reactive group of nonmetals will be VII A (VIII A is non reactive). As it comes in the end and according to group trend the most reactive element from VII A should be the top member. The first element of VII A is Fluorine (as it is the most electronegative element of periodic table).
Xenon (Xe) belongs to VIII A group of periodic table. VIII A elements are considered to be non reactive as they have 8 electrons in their outermost shell. They follow the octet rule and are stable without forming bond with any element. However as there are many exceptions in periodic table, we also have one here. Xenon forms bond with Fluorine atom. Yes, you heard it right Xenon reacts with Fluorine. The process of bond formation is very complicated. I didn’t discuss this to explain the process but to tell you about the reactivity of Fluorine. No other element of periodic table reacts with VIII A elements. Only fluorine has the ability to react with Xenon.
3 types of fluorides are formed on reaction with xenon.
Xe + F2 → XeF2
Xe + 2F2 → XeF4
Xe + 3F2 → XeF6
Reactivity is the ability of any element to form a bond with another element.
It depends upon electronegativity for nonmetals while for metals it depends on electropositivity.
Electronegativity is the ability of an element to attract the shared pair of electron towards itself.
Reactivity is directly proportional to the electronegativity of nonmetals.
In periodic table electronegativity and reactivity both increase left to right in a period and decrease from top to bottom in group.
VII A group is the most electronegative and reactive group of periodic table.
Fluorine is the most reactive nonmetal because it is the most electronegative nonmetal in the periodic table.
It’s electronegativity is 4 (highest) on Pauling’s scale.
Fluorine is the only element that reacts with Xenon of VIII A group, due to its high electronegativity value.