Test: Chemical Bonding - SSC CGL MCQ

Valency in chemistry is defined as the capacity of an atom or element to form chemical bonds. It is crucial in determining how elements combine and interact with each other to achieve stability. Understanding the concept of valency helps in predicting the types of bonds elements will form and how they will behave in chemical reactions.

An anion is an ion that carries a negative charge and has more electrons than its corresponding neutral atom. Anions form when atoms gain electrons to achieve a stable electron configuration. This extra electron(s) results in a negative charge, making the ion overall negatively charged.

The valency of a non-metal is usually determined by subtracting the number of valence electrons from eight. Since non-metals tend to gain electrons to achieve a full outer shell, this method helps in understanding how many electrons they need to gain to attain a stable electron configuration.

A positively charged ion is called a cation. Cations are formed when atoms lose electrons, resulting in a net positive charge. This loss of electrons allows the cation to achieve a more stable electron configuration, typically by forming bonds with negatively charged ions (anions) to balance out the charge.

For metals, the valency is equal to the number of valence electrons in the atom. This means that in the case of sodium (Na), its valency is 1, as it has one valence electron. Understanding the valency of metals is crucial in predicting how they will bond with other elements in chemical reactions.

A covalent bond is formed by the sharing of electrons between two atoms. This type of bond occurs when atoms share electrons to achieve a more stable electron configuration. In covalent compounds, atoms are held together by these shared electrons. The strength of the bond depends on the number of shared electron pairs. Covalent compounds are typically liquids or gases with low melting and boiling points. They do not conduct electricity and are often insoluble in water but soluble in organic solvents.

In an ionic bond, the typical electronegativity difference between the atoms involved is around 1.7. When this difference in electronegativity is significant, one atom will attract the shared electrons more strongly, leading to the transfer of electrons and the formation of an ionic bond. This results in the creation of ions, with one atom becoming positively charged (cation) and the other becoming negatively charged (anion).

A coordinate or dative covalent bond is formed by the one-sided sharing of one pair of electrons between two atoms. In this type of bond, one atom provides both electrons in the shared pair. This bond is different from a typical covalent bond, where each atom contributes one electron. The atom donating the lone pair is called the donor, while the atom accepting the pair is called the acceptor.

An ionic bond results from a large difference in electronegativity between two atoms. In this type of bond, one atom strongly attracts the shared electrons, leading to the transfer of electrons from one atom to another. The resulting ions are held together by electrostatic forces of attraction, creating an ionic compound.

Covalent compounds are distinguished from ionic compounds by the sharing of electrons between atoms. In covalent bonds, atoms share electrons to achieve a stable electron configuration. This sharing results in the formation of molecules rather than ions. Covalent compounds typically have low melting and boiling points, do not conduct electricity, and are often insoluble in water but soluble in organic solvents.

Hydrogen bonding is characterized by the electrostatic attraction between a hydrogen atom covalently bonded to a highly electronegative atom and another electronegative atom in the same or a different molecule. This type of bonding is significant in various biological processes and plays a crucial role in determining the properties of many substances.

Intermolecular hydrogen bonding, such as seen in compounds like HF and water, increases solubility in water and boiling point. This phenomenon is important in various chemical and biological systems, impacting properties like solubility and boiling points.

Van der Waals' forces are weaker than normal chemical bonds and include various interactions like dipole-dipole interactions and London dispersion forces. These forces play a crucial role in determining the physical properties of substances and are particularly notable in molecular interactions.

Compounds with O-H, N-H, or H-F bonds exhibit unusual properties due to hydrogen bonding. This includes effects such as increased viscosity and boiling points, which are significant in various chemical and biological systems.

The ability of geckos to climb sheer surfaces is primarily attributed to van der Waals' forces between their foot-pads and the surfaces. These forces enable the geckos to adhere to surfaces through intermolecular interactions, showcasing the importance of such forces in biological adaptations.