CaO (Calcium oxide) is an ionic compound because when the metal combines with nonmetal, it usually forms an ionic compound. Here, Ca is a metal and O is a nonmetal. So when they combine, it forms an ionic compound.
Well, now you have got to know that CaO is an ionic compound, but let me explain the in-depth reason why CaO is an ionic compound.
If you are a visual learner like me, then here is a short one minute video for you.
Why is CaO an ionic compound?
As mentioned above, you can simply remember that when the metal combines with nonmetal, the bond between them is an ionic bond.
Here in CaO, the Ca atom is a metal and the O atom is a nonmetal.
Hence the bond between them is an ionic bond.
How does the ionic bond form between Ca and O?
In CaO, there are two atoms;
Ca and O.
About Calcium (Ca):
Calcium atom have 20 electrons.
The electrons arrangement in Calcium (Ca) is 2, 8, 8, 2.
So the outermost orbit of Calcium atom has 2 electrons.
Now Calcium is a metal and the metals are highly electropositive (that means they have the tendency to lose electrons and become positive ions.)
Hence during the chemical reaction, the Calcium atom will lose 2 electrons to form a stable octet.
About Oxygen (O):
Oxygen atom have 8 electrons.
The electrons arrangement in Oxygen (O) is 2, 6.
So the outermost orbit of an Oxygen atom has 6 electrons.
Now Oxygen is a nonmetal and the nonmetals are highly electronegative (that means they have the tendency to gain electrons and become negative ions.)
Hence during the chemical reaction, the Oxygen atom will gain 2 electrons to form a stable octet.
What happens when Ca and O combine?
When Ca and O combine with each other, the electron transfer takes place from Calcium atom to Oxygen atom (i.e from Ca to O).
In other words, the Calcium atom (Ca) loses 2 electrons and the Oxygen atom (O) gains 2 electrons.
Due to this, Calcium becomes a positive ion (Ca2+) and Oxygen becomes a negative ion (O2-).
Now because of the positive charge of Calcium ion and negative charge of Oxygen ion, the electrostatic force of attraction is produced between them.
This electrostatic force between Calcium ion and Oxygen ion results in an ionic bond between them.
Hence, CaO is an ionic compound.
I hope you have understood the reason why CaO is an ionic compound.
Check out other compounds to see whether they are ionic or covalent;
Is KCl (Potassium chloride) Ionic or Covalent?
Is O2 Ionic or Covalent?
Is H2S Ionic or Covalent?
Is NaBr Ionic or Covalent?
Is Na2O Ionic or Covalent?
Jay is an educator and has helped more than 100,000 students in their studies by providing simple and easy explanations on different science-related topics. With a desire to make learning accessible for everyone, he founded Knords Learning, an online chemistry learning platform that provides students with easily understandable explanations.
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