Ionic bonding is the electrostatic force of attraction between two oppositely charged ions. Ionic bonding occurs between metals and nonmetals.
Examples of Ionic compounds:
NaCl
NaCl is nothing but table salt.
NaCl is made of the two elements sodium and chlorine. Sodium has 11 electrons and Chlorine has 17 electrons. To identify the number of valence electrons and their charge we need to look at the electron configuration.
The electron configuration for the first 20 elements goes like this: 2,8,8,2. The first shell needs to have 2 electrons, the second one needs 8, the third one needs 8, and the fourth one we don’t have to worry about it for now.
Sodium has 11 electrons, so 2 in the first shell, 8 in the second shell, and 1 in the 3rd shell. Chlorine has 17 electrons, so the electron configuration will be 2,8,7. Sodium has one extra electron, so it will give that way to get a charge of 1+. Chlorine has 7 valence electrons, so it will take in the one-electron that sodium gave away to attain stability and will obtain a charge of 1-. Both of these elements are now ions and have opposite charges. Opposite charges attract, so both of these ions will get attracted to each other and stay close. This attraction between the ions is the ionic bonding.
2. Magnesium and chlorine
In this case, let's construct an ionic compound.
Chlorine has 17 electrons in total, so its electron configuration will be 2,8,7.
Magnesium has 12 electrons in total, so its electron configuration will be 2,8,2.
Magnesium has 2 extra electrons, so its ion will have a charge of 2+ and chlorine takes in one electron, so its ion will have a charge of 1+. Magnesium gives away two electrons, but one chlorine atom wants only one electron, so we will take two chlorine atoms instead of one.
Magnesium will have a charge of 2+ and each chlorine atom a 1- charge.
Every compound needs to have a net charge of zero. So, over here we have a 2+ and 2- which will add up to zero, so we have our compound here.
MgCl2
3. Sodium and Oxygen
Sodium has 11 electrons, so its electron configuration will be 2,8,1.
Oxygen has eight electrons, so its electron is 2,6.
Sodium will give away that 1 extra electron to attain an octet and oxygen wants to take in 2 electrons to attain stability.
Oxygen needs two electrons, but one sodium atom can only give one electron, so we will take 2 sodium atoms instead.
Two sodium ions so a total of 2+ charge and one oxygen ion which is a total of 2- charge. Both of them add up to a net total of zero, so the charges are also balanced.
So the compound will be Na2O.
Let’s look at the properties of ionic compounds and their structure now.
Ionic compounds create an ionic lattice.
This is how a lattice structure looks. In an ionic lattice, there are so many cations and anions. Each of them is surrounded by ions of the opposite charge and they are all attracted to each other, and this is what we call ionic bonding.
Physical properties of ionic compounds:
1. Ionic compounds are solid at room temperature as the ionic bonds are really strong. Because of this same point that the bonding is really strong, these compounds also have a high boiling and melting point.
2. Ionic compounds are generally solvable in polar compounds like water. Since the bonding is just the attraction of opposite charges, when it is added to water, water also has positive and negative particles which will also attract ions in the ionic compound which splits the elements apart allowing them to dissolve.
3. Ionic compounds are good conductors of heat and electricity when in a liquid state, as they have charged particles and they can move around freely. But they can’t conduct heat or electricity in the solid-state, as the ions are all trapped in a lattice structure, so they can’t move freely.
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