Write formulas and give names for the binary hydrogen compounds of the second- period elements (Li to F). Describe the changes in physical and chemical properties of these compounds as we move across the period from left to right.

Understanding the process of chemical bonding is crucial when examining binary hydrogen compounds. These compounds are created when hydrogen bonds with elements from the periodic table, in this case, the second-period elements.

Each pairing exhibits a specific type of chemical bond that determines the compound's properties. For instance, Lithium Hydride (LiH) is formed through an ionic bond due to the significant difference in electronegativity between lithium and hydrogen. As we progress to elements like carbon in Methane (CH₄), the bonds become covalent since the electronegativity difference is less drastic.

At the far right of the period, in compounds such as Water (H₂O) and Hydrogen Fluoride (HF), the bonding has a unique character due to hydrogen's ability to form polar covalent bonds. This polarity leads to hydrogen bonding, a specific and potent intermolecular force. These intricacies in chemical bonding are integral to understanding the changing physical and chemical properties of these compounds across the periodic table.

The term 'periodic properties' refers to the patterns in properties of elements that emerge when they are arranged in the periodic table. As one moves from left to right across a period, elements like those in the second-period compounds with hydrogen exhibit changes in electronegativity, ionization energy, and bond types.

Starting with LiH, the element Lithium has a lower electronegativity, and as we move towards HF, fluorine's electronegativity is much higher. This gradual increase accounts for the transition from metallic (ionic) bonding to covalent and then to hydrogen bonding.

• Electronegativity - affects acidity or basicity of the compound.
• Ionization Energy - influences the compound's reactivity.
• Bond Type - dictates the compound's overall stability and reactivity.

These periodic properties ultimately govern the behavior of binary hydrogen compounds and explain the systematic variation in their physical and chemical characteristics.

Intermolecular forces are the forces that act between molecules, affecting the physical state and melting or boiling points of substances. In the context of binary hydrogen compounds of the second-period elements, the strength and type of these forces are pivotal.

Starting with compounds like LiH and BeH₂, the intermolecular forces are relatively weak, consisting primarily of Van der Waals forces, which is why these compounds exhibit low melting and boiling points and exist as solids. As we progress through the period to compounds like Methane (CH₄) and Ammonia (NH₃), the intermolecular forces grow stronger due to increased polarity leading to dipole-dipole interactions.

In the case of Water (H₂O), hydrogen bonds come into play, substantially increasing its boiling point compared to the others. This results in water being a liquid at room temperature, unlike the other compounds. Understanding the types and strengths of intermolecular forces is fundamental in predicting and explaining the physical properties of binary hydrogen compounds.