(a) Calculate \%IC of the interatomic bonds for the intermetallic compound \(\mathrm{Al}_{6} \mathrm{Mn}\). (b) On the basis of this result, what type of interatomic bonding would you expect to be found in \(\mathrm{Al}_{6} \mathrm{Mn}\) ?

Electronegativity difference is the measure of the disparity in electronegativity between two elements in a bond. Electronegativity itself is the ability of an atom to attract shared electrons when in a bond with another atom. In simple terms, it's like a tug-of-war over electrons; the stronger 'pull' an atom has, the higher its electronegativity.

Understanding electronegativity difference is crucial because it helps predict the type of bond that will form between two atoms:

• If the difference is large, an ionic bond is likely.
• If the difference is small, atoms tend to share electrons more equally, resulting in a covalent bond.

For example, in the Al6Mn compound, the difference in electronegativity between aluminum (Al) and manganese (Mn) is calculated to be very small (0.06). This means that the electrons are likely to be shared somewhat equally between Al and Mn atoms, hinting at a probable covalent bond formation.

The percentage ionic character (%IC) is an estimate of how much an interatomic bond behaves like an ionic bond. It's derived from the electronegativity difference between the two atoms involved using the formula, %IC = 1 - e^{-(0.06)^2/4}, which is based on the concept introduced by Linus Pauling. A higher %IC corresponds to a bond having more characteristics of an ionic bond.

In the context of Al6Mn, the %IC turned out to be approximately 0.09%. This implies that the bond has very little ionic character and is almost entirely non-ionic in nature. The tiny %IC reflects how unlikely it is for the electrons to be localized to one atom over the other, supporting the prediction that the bonding in Al6Mn is predominantly covalent.

An intermetallic compound, like Al_{6}Mn, is a specific type of alloy that holds a defined stoichiometry and crystal structure. Intermetallics differ from typical alloys since they exhibit unique chemical and physical properties due to their ordered structures. They often showcase distinct mechanical properties, such as high strength and resistance to corrosion, making them valuable in various industrial applications.

Intermetallic compounds can involve diverse types of bonding, including metallic, covalent, and ionic, although typically metallic bonds predominate. However, in the case of Al6Mn, the analysis of the %IC revealed that the interatomic bonds are primarily covalent, which is somewhat unusual for intermetallics and an interesting point of study for materials science.

Covalent bonding is characterized by the equal sharing of electrons between atoms. This type of bonding typically occurs between non-metal atoms that have similar electronegativity values, as they have comparable abilities to attract electrons towards themselves.

In a covalent bond, atoms achieve greater stability by filling up their outer electron shells, often resulting in discrete molecules or network structures like those found in diamond or quartz. Covalent bonds are strong and directional, giving rise to a variety of structural possibilities. The calculated %IC for Al6Mn suggests that the atoms share their electrons in a covalent manner, which would be responsible for bonding in the compound, leading to its unique properties, contrary to what might be expected from metallic components like Al and Mn.