4.4.6 - The Formation of Ionic Compounds From Atoms
As discussed previously, an ionic compound is made up of cations and anions. Therefore, all that is needed in order for an ionic compound to form is for a large number of cations and anions to come together.
For example, the diagram below shows how the ionic compound sodium chloride (NaCl) can form when sodium ions (Na+) and chloride ions (Cl-) come together (note that the actual numbers of ions would be a lot more than what is shown here):
The formation of sodium chloride from sodium and chloride ions.
However, the formation of an ionic compound doesn't have to start with ions. It could also start with atoms. This is because atoms can gain or lose electrons to form ions which then form the ionic compound.
For example, the formation of sodium chloride could start with sodium atoms and chlorine atoms.
Each sodium atom has one electron in its outer shell, meaning that it needs to lose one electron to get a full outer shell.
Each chlorine atom has seven electrons in its outer shell, meaning that it needs to gain one electron to form a full outer shell.
Therefore, a sodium atom can transfer one electron to a chlorine atom, resulting in them both having a full outer shell. The sodium atom becomes a sodium ion (Na+) and the chlorine atom becomes a chloride ion (Cl-). This is shown below:
A sodium atom can transfer an electron to a chlorine atom to form a sodium ion and a chloride ion.
Therefore, if a large number of sodium atoms and a large number of chlorine atoms come together, they can form the ionic compound sodium chloride. First, each sodium atom transfers an electron to a chlorine atom. Then, the sodium and chloride ions formed come together to form sodium chloride.
This process is shown in the diagram below. For simplicity, each atom or ion is simply shown as a circle.
The formation of sodium chloride from sodium and chlorine atoms.
When an ionic compound forms from atoms, one of the elements is usually a metal and the other is usually a nonmetal. This is because metals lose electrons to form cations and nonmetals usually gain electrons to form anions.
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.
How can an ionic compound be formed from atoms?
4.4.7 - Dot and Cross Diagrams of Ionic Bonding
4.4.5 - Working Out the Formula of Any Ionic Compound
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