1) The electron density in a bond refers to the number of electrons shared or transferred between two atoms in a chemical bond. The electron density can vary depending on the type of bond.
In an ionic bond, electrons are transferred from one atom to another to form ions with opposite charges that are then attracted to each other. The electron density is highest near the more electronegative atom that attracts the electrons, resulting in a separation of charges across the bond.
In a covalent bond, electrons are shared between two atoms, resulting in a shared electron density between them. The electron density is highest between the two atoms and decreases with distance from the bond.
In an intermediate or polar covalent bond, the electrons are shared unequally between the atoms, resulting in a partial charge separation across the bond. The electron density is highest near the more electronegative atom that attracts the electrons more strongly, resulting in a partial negative charge on that atom and a partial positive charge on the other.
In summary, the electron density varies in each type of bond. In an ionic bond, the electron density is highest near the more electronegative atom. In a covalent bond, the electron density is highest between the two atoms. In an intermediate or polar covalent bond, the electron density is highest near the more electronegative atom, resulting in a partial charge separation across the bond.
2) The H-O-H bond angle in water is approximately 104.5 degrees, while the H-C-H bond angle in methane is approximately 109.5 degrees. This difference in bond angle can be explained by the difference in the geometry of the two molecules.
Water has a bent or V-shaped molecular geometry due to the presence of two lone pairs of electrons on the oxygen atom. These lone pairs exert a repulsive force on the bonding pairs of electrons, pushing the two hydrogen atoms closer together and decreasing the bond angle. As a result, the H-O-H bond angle in water is less than the ideal tetrahedral angle of 109.5 degrees.
In contrast, methane has a tetrahedral molecular geometry, with the carbon atom at the center and four hydrogen atoms arranged around it in a tetrahedral shape. Each of the H-C-H bond angles is approximately 109.5 degrees, which is the ideal angle for a tetrahedral molecule.
In summary, the H-O-H bond angle in water is less than the H-C-H bond angle in methane due to the difference in molecular geometry. The presence of lone pairs on the oxygen atom in water distorts the V-shaped geometry and reduces the bond angle, while the tetrahedral geometry of methane results in ideal bond angles of approximately 109.5 degrees