Let's solve each of these
Atom Diagrams – Practice Problems step by step.
We are given the periodic table information for three elements:
Boron (B),
Carbon (C), and
Helium (He). For each, we need to determine:
- Number of
protons
- Number of
neutrons
- Number of
electrons
- Number of
valence electrons
Then, we’ll complete the atomic diagram (electron shells).
---
🔹 1) Boron (B)
From the box:
- Atomic number =
5 → This is the number of protons.
- Symbol: B
- Name: Boron
- Atomic mass ≈
10.81
#### Step-by-step:
-
Protons: = Atomic number =
5
-
Electrons: In a neutral atom = number of protons =
5
-
Neutrons: ≈ Atomic mass (rounded) − Protons
→ Round 10.81 →
11
→ Neutrons = 11 − 5 =
6
-
Valence Electrons: Boron is in
Group 13 (or Group IIIA), so it has
3 valence electrons
>
✔ Answer:
> - Protons:
5
> - Neutrons:
6
> - Electrons:
5
> - Valence Electrons:
3
#### 🧪 Drawing the Atom:
- Draw nucleus with
5 protons and
6 neutrons (you can label or just write "p⁺" and "n⁰")
- Electron shells:
- First shell (K): holds up to 2 electrons → place
2 electrons
- Second shell (L): holds up to 8 → place remaining
3 electrons
- So, electron configuration:
2, 3
> ⚛️ Diagram:
> ```
> [Nucleus: 5p⁺, 6n⁰]
> / \
> (2e⁻) (3e⁻)
> K L
> ```
---
🔹 2) Carbon (C)
From the box:
- Atomic number =
6
- Symbol: C
- Name: Carbon
- Atomic mass ≈
12.01
#### Step-by-step:
-
Protons: = Atomic number =
6
-
Electrons: Neutral atom →
6
-
Neutrons: Round atomic mass →
12
→ Neutrons = 12 − 6 =
6
-
Valence Electrons: Carbon is in
Group 14 →
4 valence electrons
>
✔ Answer:
> - Protons:
6
> - Neutrons:
6
> - Electrons:
6
> - Valence Electrons:
4
#### 🧪 Drawing the Atom:
- Nucleus: 6 protons, 6 neutrons
- Electron shells:
- K shell (first): 2 electrons
- L shell (second): 4 electrons
- Configuration:
2, 4
> ⚛️ Diagram:
> ```
> [Nucleus: 6p⁺, 6n⁰]
> / \
> (2e⁻) (4e⁻)
> K L
> ```
---
🔹 3) Helium (He)
From the box:
- Atomic number =
2
- Symbol: He
- Name: Helium
- Atomic mass ≈
4.00
#### Step-by-step:
-
Protons: = Atomic number =
2
-
Electrons: Neutral atom →
2
-
Neutrons: Atomic mass = 4 → Neutrons = 4 − 2 =
2
-
Valence Electrons: Helium is in
Group 18 (Noble gases). It has a full outer shell with
2 electrons, which is stable. So,
2 valence electrons.
>
✔ Answer:
> - Protons:
2
> - Neutrons:
2
> - Electrons:
2
> - Valence Electrons:
2
> 💡 Note: Although helium is in Group 18, it only has
2 electrons total, both in the first shell. The first shell is full at 2 electrons, so it’s stable.
#### 🧪 Drawing the Atom:
- Nucleus: 2 protons, 2 neutrons
- Only one shell (K shell): holds 2 electrons
- Configuration:
2
> ⚛️ Diagram:
> ```
> [Nucleus: 2p⁺, 2n⁰]
> |
> (2e⁻)
> K
> ```
---
✔ Final Answers Summary:
| Element | Protons | Neutrons | Electrons | Valence Electrons |
|--------|--------|---------|----------|------------------|
|
Boron (B) | 5 | 6 | 5 | 3 |
|
Carbon (C) | 6 | 6 | 6 | 4 |
|
Helium (He) | 2 | 2 | 2 | 2 |
---
🖼️ How to Complete the Diagrams:
For each circle (representing electron shells):
1.
Inner circle = first shell (K) → holds max 2 electrons
2.
Outer circle = second shell (L) → holds max 8 electrons
Draw small dots or X's to represent electrons:
-
Boron: 2 in inner, 3 in outer
-
Carbon: 2 in inner, 4 in outer
-
Helium: 2 in inner (only one shell)
Label the nucleus as having the correct number of protons and neutrons.
---
Let me know if you'd like a visual sketch of the diagrams!
Parent Tip: Review the logic above to help your child master the concept of identify the atom worksheet.
