Both covalent and ionic bonds have to do with how electrons are transferred and maintained between one atom and another present in a given compound. The chemical compound of water designated as H2O, but what exactly is the nature and form of the bond that forms between the atoms here?
Understanding what covalent and ionic bonds mean can make it easier for you to then figure out whether water is covalent and ionic. To help you out, we will take you through the kind of bond that water has and what that means for the molecules present in its structure.
- Covalent and Ionic Bonds
- Is Water Covalent or Ionic?
- Summing Up
Covalent and Ionic Bonds
How the electrons behave between two or more atoms of certain molecules can help determine whether a certain bond is covalent or ionic. You can learn more about each of these below.
A covalent bond generally involves the mutual sharing of electrons between atoms. Most typically, this tends to take place between two or more atoms that are present within the same element or have close placements to each other.
In such a situation, then, the unpaired electrons in a given atom will combine with the unpaired electrons in another atom so that all of them can achieve a shared octet in their outer electron shells.
This kind of bonding takes place because the atoms do not give away their electrons to other atoms but simply share them. If they have more than one unpaired electron and there are other atoms to share it with, then it is likely that the atom will bond with all possible atoms in the element.
An ionic bond is also referred to as an electrovalent bond. In this kind of bond, there is no mutual sharing involved between the atoms. Instead, the atom completely gives away the unpaired or valence electron present on the outermost shell to another atom.
This is usually seen between the atoms of metals and non-metals. The valence electron is transferred from one atom to another (such as from a metal atom to a non-mental atom), resulting in the formation of two different ions.
The atom that transferred the electron becomes a cation while the atom that received the electron becomes an anion, resulting in an ionic bond due to electrostatic forces between them to form a compound.
Is Water Covalent or Ionic?
Water (H2O) is a covalent bond. The hydrogen atoms that constitute water situate themselves near the oxygen atom where they can all share their valence electrons with each other, resulting in a strong bond that results in the formation of this compound.
Considering that both hydrogen and oxygen are non-metals, it is much easier for them to form a covalent bond since ionic bonds usually only form between metals and non-metals. This implies that the attraction between hydrogen and oxygen is not that strong, causing them to share their electrons instead to form a stable bond.
For a covalent bond to effectively take place, the electronegativity difference between the atoms should not be too high. This is what makes this kind of sharing more favorable. If the difference ends up being too being, this will result in the formation of an ionic bond.
To understand this process in further detail, however, it is important to understand how the distribution and bonding exactly take place. There is also another aspect of water’s covalent bond that is worth knowing about since it makes it slightly different from standard covalent bonds.
You can go through each of these aspects below.
Distribution of Electrons
There are two hydrogen atoms present in a water molecule along with one oxygen atom. Neither of these atoms have an octet in their outermost shell. Instead, each hydrogen atom has a single valence electron in the outer shell whereas oxygen has six valence electrons.
To become stable, then, each hydrogen atom needs an additional electron to pair with the valence electron while oxygen needs two more electrons to complete the octet.
This is why both hydrogen atoms and the oxygen atom combine their valence electrons to achieve stability through sharing their electrons, resulting in a covalent bond.
Polar Covalent Bond
We have now determined that water forms a covalent bond and not an ionic bond. However, even within the covalent bond, there are two distinctions as follows.
- Pure Covalent Bond: This kind of covalent bond is when the sharing of electrons between the atoms that takes place is equal in number. This is usually when the atoms present in the bonding scenario are all also equal.
For instance, in chlorine (Cl2), a pure covalent bond forms due to the equal sharing of electrons.
- Polar Covalent Bond: A polar covalent bond is one where the equal sharing of electrons does not take place, resulting in a slightly negative and positive charge in the respective atom due to the greater pull from a certain atom.
Water, for instance, has a polar covalent bond because the hydrogen atoms are not equally distributed or situated around the oxygen atom. This might occur due to the electronegativity difference or due to the occurrence of asymmetry.
The electrons that hydrogen and oxygen share, therefore, are pulled slightly more towards the oxygen nucleus instead of remaining equally firm between the two, resulting in a slightly positive charge towards hydrogen and slightly negative charge towards oxygen.
In essence, therefore, while water has a covalent bond instead of an ionic bond, the covalent bond itself is not pure and equal but is polar in structure.
This was everything you needed to know about the nature of the bond between the atoms present in a water molecule. To sum up, water has a covalent bond because the hydrogen and oxygen atoms share their electrons to become stable and complete their octet.
However, this bond is not as equal as it looks since the oxygen atom tends to pull on the electrons a bit more, resulting in each atom having a polar charge—hydrogen the positive and oxygen the negative.