Question

Ordinarily, two metals, when mixed, form alloys that show metallic character. If the two metals differ sufficiently in electronegativity, they can form compounds with significant ionic character. Consider the solid produced by mixing equal chemical amounts of Cs and Rb, compared with that produced by mixing Cs and Au. Compute the electronegativity difference in each case, and determine whether either mixture has significant ionic character. If either compound is ionic or partially ionic, which atom carries the net negative charge? Are there alkali halides with similar or smaller electronegativity differences?

Short answer

The electronegativity difference in Cs-Rb compound is 0.03. The electronegativity difference in Cs-Au is 1.75.

Cs-Au compound is ionic.

Au will have the negative charge.

The alkali halide with smaller electronegativity difference is Nal .

Step-by-step solution

Given information

It is given that a solid is formed by mixing equal amounts of Cs and Rb. Another solid is formed by mixing Cs and Au.

Electronegativity

Electronegativity is a constant value of atoms.We can determine the bonding type by finding the electronegativity difference.

Electronegativities of each atoms and their difference

The electronegativity of Cs is 0.79, Rb is 0.82, Au is 2.54.In the solid formed by mixing Cs and Rb, the electronegativity difference can be calculated as:

$0.82-0.79=0.03$

The electronegativity difference in Cs-Rb compound is 0.03

In the solid formed by mixing Cs and Au, the electronegativity difference is as follows:

$2.54-0.79=1.75$

The electronegativity difference in Cs-AU compound is 1.75.

The electronegativity difference is large in the solid of Cs and Au.

Influence of electronegativity difference with the ionic character

The ionic character depends upon the electronegativity difference. If the electronegativity difference is high, then the ionic character is also high.

In the Cs-Au compound, the electronegativity is large and thus, it has more likely to be ionic in nature.

Ion carrying net negative charge

The ion with more electronegativity attracts more electrons towards its nucleus. In Cs-Au compound, Au has more electronegativity and thus, it attracts more electrons towards its nucleus. So, 1Au will have the negative charge.

The alkali halide with smaller electronegativity difference is and the difference is 1.6.