Question

which of these actions will change the molecule geometry? changing a single bond to a double bond changing a bond to a lone pair both neither which of these actions will change the electron geometry? changing a single bond to a double bond changing a bond to a lone pair both neither

Explanation:

• For molecule geometry:
• Changing a single bond to a double bond does not change the molecule geometry as it still counts as one electron - group for the purpose of determining the basic shape (molecule geometry considers bonded atoms and lone pairs around the central atom, and double bonds are treated as one "electron - group" in VSEPR).
• Changing a bond to a lone pair changes the molecule geometry. For example, in \(NH_3\) (trigonal pyramidal, molecule geometry) compared to \(BH_3\) (trigonal planar, molecule geometry). The lone pair in \(NH_3\) repels the bonding pairs more than a bonding pair would repel another bonding pair in \(BH_3\).
• For electron geometry:
• Changing a single bond to a double bond does not change the electron geometry. Electron geometry is determined by the total number of electron - groups (single bonds, double bonds, triple bonds, and lone pairs) around the central atom. A double bond is still one electron - group.
• Changing a bond to a lone pair does not change the electron geometry. The total number of electron - groups (bonding and non - bonding) around the central atom remains the same. For example, if a central atom has 4 electron - groups (originally 4 bonds), changing one bond to a lone pair still gives 4 electron - groups (3 bonds and 1 lone pair), so the electron geometry (tetrahedral in this case) remains unchanged.

Answer:

• For "Which of these actions will change the molecule geometry?": changing a bond to a lone pair
• For "Which of these actions will change the electron geometry?": neither