4.4.1 - Ionic Bonds
So far, we have learnt about one type of bonding called covalent bonding. Now we will learn about a second type called ionic bonding.
In ionic bonding, the particles which are joined together are ions. This is different to covalent bonding, in which the particles are atoms.
Ionic bonding takes place between a cation (positively charged ion) and an anion (negatively charged ion). Because they have opposite charges, they are attracted towards each other by the electrostatic force. Due to the strength of this force, the two ions are held tightly together. This is called an ionic bond.
The diagram below shows the formation of an ionic bond between a sodium ion (Na+) and a fluoride ion (F-):
The formation of an ionic bond between a sodium ion and a fluoride ion.
In the example above, both of the ions (Na+ and F-) were monatomic ions. However, polyatomic ions can also form ionic bonds. One or both of the ions in an ionic bond can be polyatomic.
The diagram below shows an ionic bond between a beryllium ion (Be2+) - which is monatomic - and a carbonate ion (CO32-) - which is polyatomic:
An ionic bond between a beryllium ion and a carbonate ion.
And the following diagram shows an ionic bond between an ammonium ion (NH4+) and a nitrate ion (NO3-). In this example, both of the ions are polyatomic.
An ionic bond between an ammonium ion and a nitrate ion.
As explained above, an ionic bond is always between a cation and an anion.
Most of the cations that occur naturally are metal ions. This is because the metals, found towards the left of the periodic table, usually form ions by losing electrons, making them positively charged.
Most of the anions that occur naturally are nonmetal ions. This is because the nonmetals, found towards the right of the periodic table, usually form ions by gaining electrons, making them negatively charged.
Therefore, in an ionic bond, the cation is usually a metal ion and the anion is usually a nonmetal ion.
There are some exceptions to this. In fact, we have already seen one of them above. In the ionic bond between ammonium and nitrate the cation is the ammonium ion, which is a polyatomic ion made of nitrogen and hydrogen, which are both nonmetals.
However, the vast majority of ionic bonds are between a metal cation and a nonmetal anion.
Flashcards help you memorise information quickly. Copy each question onto its own flashcard and then write the answer on the other side. Testing yourself on these regularly will enable you to learn much more quickly than just reading and making notes.
What is an ionic bond?
What kinds of ions can be involved in ionic bond?
What types of element are usually involved in an ionic bond?
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