4.1 Electron-Dot Structures | Conceptual Academy - Free Printable
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Step-by-step solution for: 4.1 Electron-Dot Structures | Conceptual Academy
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Show Answer Key & Explanations
Step-by-step solution for: 4.1 Electron-Dot Structures | Conceptual Academy
You're absolutely right — this worksheet is about electron-dot structures (also called Lewis structures) and how atoms bond by sharing unpaired electrons to form molecules.
Let’s go step-by-step through each reaction, drawing the correct electron-dot structure for the product, based on the atoms given and their unpaired electrons.
---
Given: One nitrogen atom (N) with 3 unpaired electrons + 3 hydrogen atoms (H), each with 1 unpaired electron.
✔ Nitrogen has 5 valence electrons → typically shown as 3 unpaired dots and 1 lone pair (but in bonding diagrams, we focus on unpaired electrons available for bonding).
Each H has 1 unpaired electron.
→ Each H bonds with one of N’s unpaired electrons.
Final Structure:
```
H
|
H - N :
|
H
```
In electron-dot notation:
```
H
·
H : N :
·
H
```
But conventionally, we show the lone pair on nitrogen:
```
H
|
H—N: (with two dots above N representing the lone pair)
|
H
```
✔ So, draw N in center, bonded to three H atoms, and one lone pair on N.
---
Given: Two chlorine atoms (Cl), each with 7 valence electrons → 1 unpaired electron each.
→ They share their unpaired electrons to form a single bond.
Final Structure:
```
:Cl — Cl:
```
With 3 lone pairs on each Cl (6 electrons total per atom, plus 2 shared = 8).
✔ Draw two Cl atoms connected by a single bond, each with 3 lone pairs (6 dots around each Cl).
---
Given: Two nitrogen atoms (each with 3 unpaired electrons) + 4 hydrogen atoms (each with 1 unpaired electron).
→ Each N bonds to 2 H atoms, and the two N atoms bond to each other.
Total bonds: N–N single bond, and each N has two N–H bonds.
Each N ends up with 3 bonds + 1 lone pair → satisfies octet.
Final Structure:
```
H H
| |
H - N - N - H
| |
H H
```
Wait — that’s too many H’s. Actually, hydrazine is H₂N–NH₂.
So better:
```
H H
| |
N - N
| |
H H
```
Each N has one lone pair.
✔ Electron-dot structure:
```
H H
· ·
H : N — N : H
· ·
(lone pairs on each N)
```
Draw: Two N atoms bonded together, each bonded to two H atoms, and each N has one lone pair (two dots).
---
Wait — the product isn’t named here! But it says “Nitrogen, N₂ + Hydrogen, H₂” — this is likely meant to be ammonia (NH₃) again? But that was already #1.
Actually, looking at the reactants: Two N atoms (from N₂) and two H₂ molecules = 4 H atoms.
That matches hydrazine (N₂H₄) — which was #3!
So this seems like a repeat or mislabeling.
But if we take it literally: N₂ + 2H₂ → ? — the balanced reaction would be N₂ + 3H₂ → 2NH₃, but that’s not matching the atom count.
Since only 2 H₂ are shown (4 H atoms), and 2 N atoms, the only stable molecule with 2N and 4H is N₂H₄ (hydrazine) — so this is likely a duplicate of #3.
✔ So same answer as #3: N₂H₄, with structure as above.
---
Given: Two oxygen atoms (each with 2 unpaired electrons) + 2 hydrogen atoms (each with 1 unpaired electron).
→ O–O single bond, each O bonded to one H.
Each O also has 2 lone pairs.
Structure:
```
H - O - O - H
```
Each O has 2 lone pairs.
✔ Electron-dot structure:
```
H : O : O : H
·· ··
```
More clearly:
```
H H
| |
:O — O:
·· ··
```
Each O has 2 lone pairs (4 dots), and single bonds to H and to the other O.
---
Again, no product named — but given: 2 O atoms (from O₂) and 2 H atoms (from H₂) → that’s H₂O₂ (hydrogen peroxide) — which was #5!
So this is likely another duplicate.
✔ Same answer as #5: H₂O₂
---
## ✔ Final Answers (Draw These Structures):
```
H
|
H - N : (lone pair on N)
|
H
```
Or in dot form:
```
H
·
H : N :
·
H
```
(with two dots above N)
---
```
:Cl — Cl:
```
Each Cl has 3 lone pairs (6 dots total per Cl).
---
```
H H
| |
N - N
| |
H H
```
Each N has one lone pair (two dots).
---
Same structure as above.
---
```
H - O - O - H
```
Each O has 2 lone pairs.
Dot structure:
```
H : O : O : H
·· ··
```
---
Same structure.
---
## 💡 Key Concept Recap:
- Atoms bond by sharing unpaired electrons.
- Goal: Each atom (except H) gets 8 electrons (octet rule); H gets 2.
- Lone pairs are non-bonding electrons that remain on an atom.
- Use dots to represent valence electrons; lines or shared dots represent bonds.
---
✔ You can now confidently draw all these structures! Let me know if you’d like hand-drawn versions or further explanation.
Let’s go step-by-step through each reaction, drawing the correct electron-dot structure for the product, based on the atoms given and their unpaired electrons.
---
🧪 1. Ammonia, NH₃
Given: One nitrogen atom (N) with 3 unpaired electrons + 3 hydrogen atoms (H), each with 1 unpaired electron.
✔ Nitrogen has 5 valence electrons → typically shown as 3 unpaired dots and 1 lone pair (but in bonding diagrams, we focus on unpaired electrons available for bonding).
Each H has 1 unpaired electron.
→ Each H bonds with one of N’s unpaired electrons.
Final Structure:
```
H
|
H - N :
|
H
```
In electron-dot notation:
```
H
·
H : N :
·
H
```
But conventionally, we show the lone pair on nitrogen:
```
H
|
H—N: (with two dots above N representing the lone pair)
|
H
```
✔ So, draw N in center, bonded to three H atoms, and one lone pair on N.
---
🧪 2. Chlorine, Cl₂
Given: Two chlorine atoms (Cl), each with 7 valence electrons → 1 unpaired electron each.
→ They share their unpaired electrons to form a single bond.
Final Structure:
```
:Cl — Cl:
```
With 3 lone pairs on each Cl (6 electrons total per atom, plus 2 shared = 8).
✔ Draw two Cl atoms connected by a single bond, each with 3 lone pairs (6 dots around each Cl).
---
🧪 3. Hydrazine, N₂H₄
Given: Two nitrogen atoms (each with 3 unpaired electrons) + 4 hydrogen atoms (each with 1 unpaired electron).
→ Each N bonds to 2 H atoms, and the two N atoms bond to each other.
Total bonds: N–N single bond, and each N has two N–H bonds.
Each N ends up with 3 bonds + 1 lone pair → satisfies octet.
Final Structure:
```
H H
| |
H - N - N - H
| |
H H
```
Wait — that’s too many H’s. Actually, hydrazine is H₂N–NH₂.
So better:
```
H H
| |
N - N
| |
H H
```
Each N has one lone pair.
✔ Electron-dot structure:
```
H H
· ·
H : N — N : H
· ·
(lone pairs on each N)
```
Draw: Two N atoms bonded together, each bonded to two H atoms, and each N has one lone pair (two dots).
---
🧪 4. Nitrogen (N₂) + Hydrogen (H₂) → ?
Wait — the product isn’t named here! But it says “Nitrogen, N₂ + Hydrogen, H₂” — this is likely meant to be ammonia (NH₃) again? But that was already #1.
Actually, looking at the reactants: Two N atoms (from N₂) and two H₂ molecules = 4 H atoms.
That matches hydrazine (N₂H₄) — which was #3!
So this seems like a repeat or mislabeling.
But if we take it literally: N₂ + 2H₂ → ? — the balanced reaction would be N₂ + 3H₂ → 2NH₃, but that’s not matching the atom count.
Since only 2 H₂ are shown (4 H atoms), and 2 N atoms, the only stable molecule with 2N and 4H is N₂H₄ (hydrazine) — so this is likely a duplicate of #3.
✔ So same answer as #3: N₂H₄, with structure as above.
---
🧪 5. Hydrogen Peroxide, H₂O₂
Given: Two oxygen atoms (each with 2 unpaired electrons) + 2 hydrogen atoms (each with 1 unpaired electron).
→ O–O single bond, each O bonded to one H.
Each O also has 2 lone pairs.
Structure:
```
H - O - O - H
```
Each O has 2 lone pairs.
✔ Electron-dot structure:
```
H : O : O : H
·· ··
```
More clearly:
```
H H
| |
:O — O:
·· ··
```
Each O has 2 lone pairs (4 dots), and single bonds to H and to the other O.
---
🧪 6. Oxygen (O₂) + Hydrogen (H₂) → ?
Again, no product named — but given: 2 O atoms (from O₂) and 2 H atoms (from H₂) → that’s H₂O₂ (hydrogen peroxide) — which was #5!
So this is likely another duplicate.
✔ Same answer as #5: H₂O₂
---
## ✔ Final Answers (Draw These Structures):
1. Ammonia, NH₃
```
H
|
H - N : (lone pair on N)
|
H
```
Or in dot form:
```
H
·
H : N :
·
H
```
(with two dots above N)
---
2. Chlorine, Cl₂
```
:Cl — Cl:
```
Each Cl has 3 lone pairs (6 dots total per Cl).
---
3. Hydrazine, N₂H₄
```
H H
| |
N - N
| |
H H
```
Each N has one lone pair (two dots).
---
4. Nitrogen + Hydrogen → N₂H₄ (same as #3)
Same structure as above.
---
5. Hydrogen Peroxide, H₂O₂
```
H - O - O - H
```
Each O has 2 lone pairs.
Dot structure:
```
H : O : O : H
·· ··
```
---
6. Oxygen + Hydrogen → H₂O₂ (same as #5)
Same structure.
---
## 💡 Key Concept Recap:
- Atoms bond by sharing unpaired electrons.
- Goal: Each atom (except H) gets 8 electrons (octet rule); H gets 2.
- Lone pairs are non-bonding electrons that remain on an atom.
- Use dots to represent valence electrons; lines or shared dots represent bonds.
---
✔ You can now confidently draw all these structures! Let me know if you’d like hand-drawn versions or further explanation.
Parent Tip: Review the logic above to help your child master the concept of lewis dot structures worksheet.
