Forming covalent compounds

We know that metal and non-metal atoms engage in a lovely dance of electron transfer leading up to an everlasting marriage as a pair of ions.

Yet before they were destined to meet a metal atom, non-metal atoms engage in covalent bonding.

What for?

Non metals lack just a few more electrons to obtain a full electron shell, therefore since their outer shell can accommodate up to 8, they naturally let their outer shell overlap with another non-metal to share electrons.

This is how oxygen atoms enjoy full electron shell before they really go out there and date metal atoms

Covalent means Co (share) and valent (outer shell)

It refers to the sharing of electrons within the overlap of atoms’ outer shells.

One way to visualise this is to imagine at atom as a table with some chairs:

Chlorine atom

Chlorine with outer shell electrons in blue

Chlorine atom needs one electron and Hydrogen also needs an electron so their shells or stools conveniently overlap like this!


Good to remember: Covalent bonds are formed by sharing electrons between the overlapping regions of 2 outer shells

Covalent bonds are very strong because it is right smack between the 2 nuclei of the bonding atoms.

It’s just like being stuck by double-sided tape!

The electron is attracted firmly to positively charged nuclei on both sides!

Must take note: Covalent bonds are very strong!

Are some covalent bonds stronger than others? You bet!

There is covalent  bonding in Cl-Cl or H-H, but these are weaker than O=O,

because the lines indicate number of covalent bonds formed!

One covalent bond is formed by sharing a pair of electrons,

double covalent bonds are formed by sharing 2 pairs,

and triple bonds are sharing 3 pairs!

As you might expect, 3 double sided tapes provides more stickiness than 1, so nitrogen with its triple bonds makes it very hard for the double-bonded nitrogen to split compared to oxygen or hydrogen.

Examples of covalent bonding

Any 2 atoms sharing a covalent bond is known as a MOLECULE!

Notice that some elements form different numbers of covalent bonds?

We can divide covalent bonding atoms into 2 types!

Central atom side atom
Carbon (4 bonds), nitrogen (3 bonds) Hydrogen (1 bond), oxygen (2 bonds)

central atom

Carbon fits the role of the central atom because it has space for 4 covalent bonds!

Side atoms on the other hand usually take one seat (or two) and that’s about it.

In terms of molecules formed,

central atom + other side atoms = simple molecular structure

central atoms + other central atoms = Giant covalent structure

“Giant” is appropriate here due to the extensiveness of covalent bonds in Giant covalent structures such as Diamond!

This is Carbon (Group IV) atoms

This can just go on and on and on and on without ending!

This are Phosphorus (group V) atoms

Next up:

learn more about COMPLEX IONS!

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