Write the Lewis structure for each ion
Al3+
Mg3+
Se2-
N3-
My question is why does Se2- get a bracket and 8 dots. And the same for N3-. I hope I'm making sense.
To determine the Lewis structures of ions, we need to consider the number of valence electrons present in the neutral atom and the charge of the ion.
In the Lewis structure, each dot represents a valence electron of the atom/ion, and each line represents a pair of shared electrons (a bond).
Let's first consider the Lewis structure of Al³⁺:
- Aluminum (Al) belongs to Group 13 in the periodic table, and it has 3 valence electrons.
- When it forms the Al³⁺ ion, it loses 3 electrons to achieve a stable electron configuration.
- Therefore, the Lewis structure of Al³⁺ can be represented as Al with three dots around it: Al³⁺: ..
Now, let's look at Mg³⁺:
- Magnesium (Mg) belongs to Group 2 in the periodic table, and it has 2 valence electrons.
- By losing all its valence electrons, it forms the Mg³⁺ ion with a stable electron configuration.
- Therefore, the Lewis structure of Mg³⁺ can be represented as Mg with three dots around it: Mg³⁺: ..
Now, let's move on to the Lewis structures of anions, starting with Se²⁻:
- Selenium (Se) belongs to Group 16 in the periodic table, and it has 6 valence electrons.
- When it gains two more electrons, it achieves a stable electron configuration like its nearest noble gas, which is krypton (Kr).
- To represent this gain of two electrons, we use a bracket with a negative sign inside and two dots added to the right side of the bracket: [Se]²⁻: ..
Similarly, let's consider N³⁻:
- Nitrogen (N) belongs to Group 15 in the periodic table, and it has 5 valence electrons.
- By gaining three more electrons, it achieves a stable electron configuration like its nearest noble gas, which is neon (Ne).
- For N³⁻, a bracket with a negative sign inside and three dots added to the right side of the bracket represent the gain of three electrons: [N]³⁻: ...
So, the reason for using brackets and adding dots for ions like Se²⁻ and N³⁻ is to indicate the gain of electrons and represent the ion's stable electron configuration in comparison to its closest noble gas.
Yes, you're making perfect sense! The reason why Se2- and N3- have brackets and 8 dots is because these ions have gained extra electrons, resulting in a negative charge. Let's go step-by-step to draw the Lewis structures for each ion:
1. Al3+ ion:
The Lewis structure for Al3+ can be created by following these steps:
Step 1: Determine the total number of valence electrons: Al has 3 valence electrons.
Step 2: Since Al loses 3 electrons to become Al3+, subtract 3 electrons from the total.
Therefore, the Lewis structure for Al3+ is represented as Al3+: Al with no dots around it, as it lost all of its valence electrons.
2. Mg3+ ion:
The Lewis structure for Mg3+ can be created by following these steps:
Step 1: Determine the total number of valence electrons: Mg has 2 valence electrons.
Step 2: Since Mg loses 2 electrons to become Mg3+, subtract 2 electrons from the total.
Therefore, the Lewis structure for Mg3+ is represented as Mg3+: Mg with no dots around it, as it lost all of its valence electrons.
3. Se2- ion:
The Lewis structure for Se2- can be created by following these steps:
Step 1: Determine the total number of valence electrons: Se has 6 valence electrons.
Step 2: Since Se gains 2 electrons to become Se2-, add 2 electrons to the total.
Step 3: Place brackets around the Se symbol to represent the ion.
Step 4: Put 8 dots around the symbol, representing the 8 electrons (2 lone pairs) gained by Se.
Therefore, the Lewis structure for Se2- is represented as [Se]2- with 8 dots around the symbol.
4. N3- ion:
The Lewis structure for N3- can be created by following these steps:
Step 1: Determine the total number of valence electrons: N has 5 valence electrons.
Step 2: Since N gains 3 electrons to become N3-, add 3 electrons to the total.
Step 3: Place brackets around the N symbol to represent the ion.
Step 4: Put 8 dots around the symbol, representing the 8 electrons (1 lone pair and 1 bonding pair) gained by N.
Therefore, the Lewis structure for N3- is represented as [N]3- with 8 dots around the symbol.
I hope this explanation helps! Let me know if you have any further questions.