- Draw the Lewis structure for the disulfur monoxide (S20) molecule. Be sure to include all resonance structures that satisfy the octet rule.
- Choose all the common ions that are isoelectronic with Ne.
Al3+, Cl-, S2-, F-, Li+, C4-, N3-, Mg2+, Br, Na+, Ca2+, O2-, K+
The correct answer and explanation is:
1. Lewis Structure for Disulfur Monoxide (S₂O)
Disulfur monoxide (S₂O) consists of two sulfur (S) atoms and one oxygen (O) atom. To draw its Lewis structure:
Steps:
- Determine total valence electrons:
- Sulfur (S) has 6 valence electrons, and there are 2 sulfur atoms.
- Oxygen (O) has 6 valence electrons.
- Total valence electrons = 6×2+6=186 \times 2 + 6 = 18.
- Draw a skeleton structure:
Connect the atoms as S−S−OS-S-O, with sulfur as the central atoms and oxygen bonded to one of the sulfurs. - Distribute electrons to satisfy the octet rule:
- Place lone pairs around the oxygen atom to complete its octet.
- Place remaining electrons around sulfur atoms to satisfy their octets.
- Check resonance structures:
There are two valid resonance structures for S₂O, as electrons can be redistributed between the double bonds and lone pairs.
Resonance Structures:
- O=S−SO=S-S: Oxygen forms a double bond with one sulfur, and the second sulfur has a single bond with the first sulfur. Each sulfur has lone pairs.
- O−S=SO-S=S: Oxygen forms a single bond with one sulfur, and the second sulfur has a double bond with the first sulfur.
Both structures obey the octet rule, and the actual structure is a resonance hybrid of the two.
2. Common Ions Isoelectronic with Neon (Ne)
Isoelectronic species are atoms or ions with the same number of electrons as a given element. Neon (Ne) has 10 electrons.
List of Ions:
- Al3+\text{Al}^{3+}: 13 – 3 = 10 electrons (Isoelectronic)
- Cl−\text{Cl}^-: 17 + 1 = 18 electrons (Not isoelectronic)
- S2−\text{S}^{2-}: 16 + 2 = 18 electrons (Not isoelectronic)
- F−\text{F}^-: 9 + 1 = 10 electrons (Isoelectronic)
- Li+\text{Li}^+: 3 – 1 = 2 electrons (Not isoelectronic)
- C4−\text{C}^{4-}: 6 + 4 = 10 electrons (Isoelectronic)
- N3−\text{N}^{3-}: 7 + 3 = 10 electrons (Isoelectronic)
- Mg2+\text{Mg}^{2+}: 12 – 2 = 10 electrons (Isoelectronic)
- Br\text{Br}: 35 electrons (Not isoelectronic)
- Na+\text{Na}^+: 11 – 1 = 10 electrons (Isoelectronic)
- Ca2+\text{Ca}^{2+}: 20 – 2 = 18 electrons (Not isoelectronic)
- O2−\text{O}^{2-}: 8 + 2 = 10 electrons (Isoelectronic)
- K+\text{K}^+: 19 – 1 = 18 electrons (Not isoelectronic)
Correct Answers:
- Al3+,F−,C4−,N3−,Mg2+,Na+,O2−\text{Al}^{3+}, \text{F}^-, \text{C}^{4-}, \text{N}^{3-}, \text{Mg}^{2+}, \text{Na}^+, \text{O}^{2-}
Explanation:
Each of the selected ions has 10 electrons, matching Neon. This is achieved by losing or gaining electrons until their total matches Neon’s electron configuration, ensuring chemical stability. Isoelectronic ions have similar electronic structures but different nuclear charges, influencing their properties. For example, O2−\text{O}^{2-} and F−\text{F}^- are both isoelectronic with Ne but differ in their ionic sizes and chemical behavior due to differences in nuclear attraction.