Question 10 · Complements de química URV Exam Bridging Courses in Chemistry

Rank the following chemical species in descending order of melting point: Li, LiCl, Ar, Fe, BaO, NH3.

Solución: $\text{BaO} > \text{Fe} > \text{LiCl} > \text{Li} > \text{NH}_3 > \text{Ar}$

Specify whether each substance is molecular or non-molecular.

Solución: BaO: Non-molecular; Fe: Non-molecular; LiCl: Non-molecular; Li: Non-molecular; NH3: Molecular; Ar: Molecular

Constitutional units of BaO

Solución: $\text{Ba}^{2+}$ and $\text{O}^{2-}$ ions

Primary type of bonding holding solid BaO together

Solución: Ionic bond

Constitutional units of Fe

Solución: $\text{Fe}^{n+}$ cores in an electron sea

Primary type of bonding holding solid Fe together

Solución: Metallic bond

Constitutional units of LiCl

Solución: $\text{Li}^+$ and $\text{Cl}^-$ ions

Primary type of bonding holding solid LiCl together

Solución: Ionic bond

Constitutional units of Li

Solución: $\text{Li}^+$ cations in an electron sea

Primary type of bonding holding solid Li together

Solución: Metallic bond

Constitutional units of NH3

Solución: $\text{NH}_3$ molecules

Primary type of bonding holding solid NH3 together

Solución: Hydrogen bonding / dipole-dipole interactions

Constitutional units of Ar

Solución: $\text{Ar}$ isolated atoms

Primary type of bonding holding solid Ar together

Solución: London dispersion forces