Electron configuration and orbital diagram worksheet for chemistry students to practice writing configurations and filling orbitals.

Let's solve each element step by step, providing:

- Full electron configuration
- Short-hand (noble gas) electron configuration
- Orbital diagram (using arrows to represent electrons in orbitals)

We'll follow the Aufbau principle, Pauli exclusion principle, and Hund’s rule.

---

1. Nitrogen (N)

- Atomic number: 7 → 7 electrons

#### Full:
1s² 2s² 2p³

#### Short-hand:
[He] 2s² 2p³

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑ ↑ ↑
```

(Each box represents an orbital. The 2p subshell has three orbitals: 2px, 2py, 2pz. Electrons fill singly first before pairing.)

✔ Filling:
- 1s: 2 electrons (paired)
- 2s: 2 electrons (paired)
- 2p: 3 electrons — one in each of the three orbitals (unpaired, following Hund’s rule)

---

2. Sodium (Na)

- Atomic number: 11 → 11 electrons

#### Full:
1s² 2s² 2p⁶ 3s¹

#### Short-hand:
[Ne] 3s¹

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑
```

- 1s, 2s, 2p are fully filled (10 electrons)
- 3s has 1 unpaired electron

---

3. Chlorine (Cl)

- Atomic number: 17 → 17 electrons

#### Full:
1s² 2s² 2p⁶ 3s² 3p⁵

#### Short-hand:
[Ne] 3s² 3p⁵

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑
```

- 3p has 5 electrons → two orbitals are paired, one has a single electron (unpaired)

---

4. Calcium (Ca)

- Atomic number: 20 → 20 electrons

#### Full:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s²

#### Short-hand:
[Ar] 4s²

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑↓
4s: ↑↓
```

- All orbitals up to 4s are filled.
- 4s is full (2 electrons), no unpaired electrons.

---

5. Gallium (Ga)

- Atomic number: 31 → 31 electrons

#### Full:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹

> Note: After 4s, we fill 3d before 4p.

#### Short-hand:
[Ar] 4s² 3d¹⁰ 4p¹

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑↓
4s: ↑↓
3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓
4p: ↑
```

- 3d is completely filled (10 electrons)
- 4p has 1 electron (unpaired)

---

6. Krypton (Kr)

- Atomic number: 36 → 36 electrons

#### Full:
1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶

#### Short-hand:
[Kr] → but since Kr is the noble gas itself, short-hand is just [Kr]

Wait — actually, for Kr, the shorthand is just [Kr], but since it's the element itself, we write the full configuration or just [Kr].

But typically, when writing short-hand for Kr, we use [Kr] as the noble gas core — but since Kr is the last element in the period, its shorthand is just [Kr].

So:
- Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
- Short-hand: [Kr]

#### Orbital Diagram:
All orbitals up to 4p are filled:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑↓
4s: ↑↓
3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓
4p: ↑↓ ↑↓ ↑↓
```

- All orbitals are fully filled → all electrons paired

---

✔ Final Answers:

---

#### 1. Nitrogen
- Full: 1s² 2s² 2p³
- Short-hand: [He] 2s² 2p³
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑ ↑ ↑
```

---

#### 2. Sodium
- Full: 1s² 2s² 2p⁶ 3s¹
- Short-hand: [Ne] 3s¹
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑
```

---

#### 3. Chlorine
- Full: 1s² 2s² 2p⁶ 3s² 3p⁵
- Short-hand: [Ne] 3s² 3p⁵
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑
```

---

#### 4. Calcium
- Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s²
- Short-hand: [Ar] 4s²
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓
```

---

#### 5. Gallium
- Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p¹
- Short-hand: [Ar] 4s² 3d¹⁰ 4p¹
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑
```

---

#### 6. Krypton
- Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
- Short-hand: [Kr]
- Orbital Diagram:
```
1s: ↑↓ 2s: ↑↓ 2p: ↑↓ ↑↓ ↑↓ 3s: ↑↓ 3p: ↑↓ ↑↓ ↑↓ 4s: ↑↓ 3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 4p: ↑↓ ↑↓ ↑↓
```

---

🔍 Summary Tips:

- Aufbau Order: Fill orbitals from lowest to highest energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p...
- Hund’s Rule: Electrons fill degenerate orbitals (like 2p, 3p, etc.) singly before pairing.
- Pauli Exclusion: Each orbital holds max 2 electrons with opposite spins (↑↓).

Let me know if you'd like this formatted into a printable version!