Metals & Non-metals - Class 10th Science
Reaction of metals and non-metals
How do Metals and Non-metals React?
A metal always reacts with a non-metal. No two metals react with each other. An atom reacts with other atom because valence electron or valency.
Valency
Valency is the combining capacity. Valency may have negative or positive.
Example
In HCl, the valency of hydrogen ion is +1 (plus one) and the valency of chloride is – 1 (minus one).
Since, a compound is neutral, so in HCl to neutralize +1 (plus one) valency hydrogen combine with one chloride ion having valency equal to – 1 (minus one).
In NaCl, the valency of sodium ion is +1 (plus one) and the valency of chloride is – 1 (minus one).
Similarly, in NaCl to neutralize +1 (plus one) valency sodium combine with one chloride ion having valency equal to – 1 (minus one).
In KBr, the valency of potassium ion is +1 (plus one) and the valency of bromide ion is – 1 (minus one).
In KBr, to neutralize +1 (plus one) valency potassium combine with one bromide ion having valency equal to – 1 (minus one).
In H
Valence Electron
Number of electrons present in outermost orbit of an atom is called valence electrons.
Example:
Hydrogen atom
Atomic number of hydrogen = 1
Electronic configuration: 1
No. of electrons present in outermost orbit: 1
Thus, valence electron of hydrogen = 1
Sodium atom
Atomic number of sodium = 11
Electronic configuration: 2, 8, 1
Number of electrons present in outermost orbit = 1
Thus, valence electron of sodium = 1
Chlorine atom
Atomic number of chlorine = 17
Electronic configuration of chlorine = 2, 8, 7
Number of electrons present in outermost orbit = 7
Thus, valence electron = 7
Noble Gas
Helium, Neon, Argon, Krypton, Xenon and Radon are noble gas. These elements are called noble because they do not react. In other word, noble gases are non-reactive.
Valence Electron of Noble gas
Valence electron of noble gas is zero. This means outermost orbit of noble gas are completely filled. Helium has total number of 2 (two) electrons in its outermost orbit. And rest of the noble gases has total number of 8 (eight) electrons in their outermost orbit.
Noble gas has stable configuration. So, they are un-reactive.
Stable and unstable configuration
Completely filled outermost orbit is considered as stable configuration. So, in order to achieve stability every atom has tendency to fill their outermost orbit completely. In other words, since outermost orbit of noble gases are completely filled, so atom of every elements have achieve the electronic configuration of their nearest noble gas.
Example
Hydrogen
Total number of electrons in outermost orbit of hydrogen is equal to 1 (one).
Nearest noble gas of hydrogen is helium.
Total number of electrons in outermost orbit of helium is equal to 2 (two).
Thus, in order to achieve stable configuration, hydrogen has tendency to achieve two electrons in its outermost orbit. This is the cause that hydrogen atom does not exist in free state in nature, rather hydrogen exists in the form of hydrogen molecule (H2).
Sodium
Total number of electrons in outermost orbit of sodium is equal to 1 (one).
Nearest noble gas of sodium is neon.
Total number of electrons in outermost orbit of neon is equal to 8 (two).
Thus, in order to achieve stable configuration, sodium has tendency to achieve eight electrons in its outermost orbit. This is the cause that sodium makes compound.
Formation of chemical compound to achieve stable configuration
In order to achieve stable configuration, an atom forms bond with atom of same element or atom of different elements. Such bonds are called Chemical Bonds.