Question

Before the element scandium was discovered in 1879, it was known as “eka-boron.” Predict the properties of scandium from averages of the corresponding properties of its neighboring elements in the periodic table. Compare your predictions with the observed values in Appendix F.

Short answer

The calculated physical properties of the scandium element are nearer but not exact to the observed values

Step-by-step solution

Electronic configuration of scandium (Sc). 

The atomic number of the scandium (Sc) element is twenty-one (21). Therefore, the electronic configuration of scandium is$\left[\text{Ar}\right]{\text{4s}}^{\text{2}}{\text{3d}}^{\text{1}}$. The valance is three (3), and it is in between calcium (2) and titanium (4).

Physical properties of scandium.

The physical properties of the scandium element are the average of the corresponding properties of its neighboring elements.

1. Calculation of the melting point of scandium.

$$\begin{gathered} \text{=}\frac{\text{839 + 1660}}{\text{2}} \\ \text{=}\frac{\text{2499}}{\text{2}} \\ \text{= 1250}{}^{\text{o}}\text{C} \end{gathered}$$

The observed melting point isrole="math" localid="1663678006781" $\text{1541}{}^{\text{o}}\text{C}$.

2 Calculation of the boiling point of scandium.

$$\begin{gathered} \text{=}\frac{\text{1484 + 3287}}{\text{2}} \\ \text{=}\frac{\text{4771}}{\text{2}} \\ \text{= 2386}{}^{\text{o}}\text{C} \end{gathered}$$

The observed boiling point of the scandium element is$2381{}^{\text{o}}\text{C}$.

3 Calculation of the density of scandium.

$$\begin{gathered} \text{=}\frac{\text{1.55 + 4.50}}{\text{2}} \\ \text{=}\frac{\text{6.06}}{\text{2}} \\ {\text{= 3.02 g/cm}}^{\text{3}} \end{gathered}$$

The observed density of the scandium element is${\text{2.99 g/cm}}^{\text{3}}$.