Question

Assign formal charges to the atoms in the following species, and then select the more likely skeletal structure. (a) \(\mathrm{H}_{2} \mathrm{NOH}\) or \(\mathrm{H}_{2} \mathrm{ONH}\) (b) SCS or CSS (c) NFO or FNO (d) \(\mathrm{SOCl}_{2}\) or \(\mathrm{OSCl}_{2}\) or \(\mathrm{OCl}_{2} \mathrm{S}\) (e) \(\mathrm{F}_{3} \mathrm{SN}\) and \(\mathrm{F}_{3} \mathrm{NS}\)

Short answer

Assigning formal charges will help to determine the most likely skeletal structure for each listed compound.

Step-by-step solution

Understand Formal Charge

The formal charge on an atom is calculated by subtracting the sum of the number of lone pair electrons and half the number of bonding electrons from the total number of valence electrons. A neutral molecule would have total formal charges equal to 0.

Assigning Formal Charges for Compound (a)

For (a) \(\mathrm{H}_{2} \mathrm{NOH}\) and \(\mathrm{H}_{2} \mathrm{ONH}\). Calculate the formal charges for each nitrogen and oxygen in the two compounds. Based on the calculated values and the rule where the most electronegative atom usually carries the negative formal charge, choose the one that follows this rule the most.

Repeat for Other Compounds

Perform the same calculations and analysis for compounds (b) SCS or CSS, (c) NFO or FNO, (d) \(\mathrm{SOCl}_{2}\) or \(\mathrm{OSCl}_{2}\) or \(\mathrm{OCl}_{2} \mathrm{S}\), and (e) \(\mathrm{F}_{3} \mathrm{SN}\) and \(\mathrm{F}_{3} \mathrm{NS}\).

Draw Skeletal Structures

With the gained knowledge about most likely formal charges, proceed to draw the skeletal structures for each of the compounds. The structure that results in the least amount of charges is the more likely skeletal structure.

Key concepts

Molecular Structures

Molecular structures are visual representations showing how atoms in a molecule are connected and arranged. They help understand which atoms are directly bonded and reveal the molecule's overall shape. When analyzing structures, you often start by identifying the 'skeletal structure' or backbone of the molecule. This approach simplifies more complex molecules by focusing on where and how main elements connect.

One can represent molecular structures using Lewis structures, which include lone pairs of electrons and bonding pairs of electrons. These visualizations help to predict and justify actual molecular geometry. Changes in skeletal structure affect molecular properties like polarity and reactivity.

• A strong skeletal structure leads to more stable compounds.
• Structure arrangement determines the molecule's function and reactivity.
• Flexibility in a skeletal structure may relate to its potential for energy storage and movement.

Valence Electrons

Valence electrons are the outermost electrons of an atom and play a key role in bonding. These electrons determine how an element can bond with others, affecting the molecule's electronic structure and stability.

In chemical reactions, atoms strive to have a full valence shell, either by sharing, gaining, or losing electrons. Understanding how many valence electrons each atom has is crucial to drawing accurate Lewis structures for a molecule. This knowledge helps predict molecule reactivity and how it will interact with others.

• Valence electrons are crucial for predicting and understanding chemical bonding.
• Atoms aim for a full outer shell similar to noble gases, a principle called the octet rule.
• Keen insight into valence electrons assists in determining Lewis structures.

Electronegativity

Electronegativity describes an atom's ability to attract bond electrons. It's measured on a scale with fluorine as the most electronegative element. Electronegativity differences between atoms in a bond determine the bond's nature—nonpolar covalent, polar covalent, or ionic.

When addressing formal charge and skeletal structures, electronegativity is a guiding principle. Generally, the atom with the higher electronegativity in a molecule carries a negative formal charge if any exist. As you place atoms in larger structures, consider their electronegativity values to create stable compounds.

• Helps predict bond type (ionic, polar covalent, nonpolar covalent).
• Central to determining which atom might carry extra electrons (negative charge).
• Influences molecular geometry and polarity, hence chemical properties.

Chemical Bonding

Chemical bonding involves the interaction of atoms to form larger structures, like molecules or compounds. Understanding different bonds helps explain how molecules hold together and interact. In essence, bonds involve either the sharing or transfer of electrons.

The main types of chemical bonds include covalent, ionic, and metallic bonding. Covalent bonds involve electrons shared between atoms, while ionic bonds occur when electrons are transferred, creating charged particles. The nature of these bonds impacts not only the compound's structure but also its physical and chemical properties.

• Covalent bonds contribute to the molecule's shape and rigidity.
• Ionic bonds often lead to the formation of crystalline structures.
• Bond strength and length affect reactivity and stability.