Electron Sharing Reactions · Paper 1 — Free Chemistry SL Practice Questions

A molecule of hydrogen chloride, HCl, is formed when hydrogen gas reacts with chlorine gas. Hydrogen has one valence electron and chlorine has seven valence electrons. Which statement correctly describes the bond formed in HCl?

In the Lewis structure of $\text{N}_2$, each nitrogen atom has five valence electrons. How many lone pairs are present on each nitrogen atom?

Oxygen gas ($\text{O}_2$) and water ($\text{H}_2\text{O}$) are both covalent molecules. Which of the following correctly identifies the bond types present in $\text{O}_2$ and $\text{H}_2\text{O}$?

When a $\text{Cl}_2$ molecule forms from two separate chlorine atoms, the Cl–Cl bond enthalpy is $+242 \ \text{kJ mol}^{-1}$. What is the change in potential energy of the system when this bond forms?