Bondings

What is Bonding?

Atoms bond to become stable and an atom that is stable consists of 8 electrons in its outer shell. This is known as a nobel gas configuration and can also be known as a stable atom.

There are three types of bondings in between atoms of elements.
They are:
- Ionic
- Covalent
- Metallic

What are these different types of bondings and how do they work?

Ionic Bonding

Ionic bonding is a chemical bond between two oppositely charged ions. Exists between ions, positive and negative. Atoms bond to become stable. To do this they can gain electrons (and become a negative ion) or lose electrons (become a positive ion). For example Na – sodium (1 electron in the outer shell) and Cl – Chlorine (7 electrons in the outer shell), to achieve two stability the sodium atom gives away the one and only electron from its outer shell to the chlorine atom and chorine which has 7 electrons in its outer shell becomes stable because the electron that sodium lost was given to chlorine and the atom now has 8 electrons in its outer shell. And because Sodium (Na) gave away an electron it becomes a positive ion and Chlorine that gained an electron becomes a negative ion. Both atomic species now have ‘full’ outer shells; They have a Nobel Gas Configuration.

Covalent Bonding

Covalent bonding is a chemical bond where two atoms of the same element share an electron pair between themselves. An example of covalent bonding is the substance we call oxygen. Also when talking about it on paper or discussing it we can talk about each oxygen atom separately, in reality oxygen is almost always found in 2's. This is because oxygen atoms covalently bond with one and other to achieve stable configuration. Oxygen is an element that consists of 6 electrons in its outer shell, meaning that it is a reactive substance (it reacts to other substances easily) when it is on its own. But when oxygen is bonded together with another oxygen atom it is not reactive. The way this covalent bonding working within both oxygen atoms is that both of the atoms share a double electron pair within each other. Meaning that they share not only 1 but two electrons from their outer shell with the other atom, so 4 electrons are being shared within both oxygen atoms. Ultimately, the four other electrons on each atom and the 4 electrons being shared in the middle among the two electrons gives both of the oxygen atoms a stable outer shell and so they have achieved nobel gas configuration. But if separated from each other the oxygen atoms will be highly reactive.

A covalent bond between two oxygen atoms

Metallic Bonding

Metals form giant structures in which electrons in the outer shells of the metal atoms are free to move. The metallic bond is the force of attraction between these free electrons and metal ions. Metallic bonds are strong, so metals can maintain a regular structure and usually have high melting and boiling points.

Definitions

“Definitions of unknown words encountered in this unit”

Ion – Charged atom (positive or negative charge)
Losing electron > Positive Ion = Cation
Gaining electron > Negative Ion = Anion
Outer shell or valence – in the outer most ring of an atom of an element which consists of given number of electrons according to element.
Delocalised electrons – are electrons that are not associated with a single atom or covalent bond.

GLOBAL CONTEXT: For this unit it is "Globalisation and sustainability the interconnectedness of human-made systems and communities."