Science Perspectives 10 - Section 5.6 Pages 192-195
• A Pure Substance composed of two or more elements in a FIXED RATIO
• A compound made up of one or more positive metal ions (cations) and one or more negative non-metal ions (anions)
• The simultaneous strong attraction of positive and negative ions in an ionic compound.
As noted, ionic bonding occurs between metals and non-metals. Yet, “why and how” does this type of bonding occur?
Figure 1 shows the element Neon. Neon is a NOBLE GAS found in Group 18. As such, its outer shell (VALENCE) has the maximum number of electrons (i.e., the outer shell is full). Thus, the electron configuration is STABLE. In other words, Noble Gases are not reactive.
Figure 2 is the element Nitrogen. Its outer shell is NOT full. Thus, the electron configuration is UNSTABLE. To become stable (i.e., have an outer shell with the maximum number of electrons), nitrogen will either GIVE AWAY or TAKE electrons from another element. When this happens, the NITROGEN ION is formed.
In an IONIC BOND, an ion with a positive charge (cation)
will give away electrons while an ion with a negative charge (anion) will take electrons.
• In every ionic bond, the cation typically has a small ionization energy (i.e., it has a “small amount of energy” to hold its electrons) while the anion has a large electron affinity (i.e., it has a “large amount of energy” to attract electrons). When the two elements are close together, the affinity exceeds the ionization energy, the electron “moves” from the cation to the anion, and an ionic compound “linking” the two ions is formed. • In a stable state (i.e., a full outer shell or a full VALENCE OCTET of electrons) , the energy state is at its lowest. This is preferred. This is stability. Elements seek to be at this low energy state. Breaking the ionization energy hold or...