This worksheet provides practice for writing full and short-hand electron configurations and drawing orbital diagrams for six common elements.

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), paired.

---

5. Gallium (Ga)

- Atomic number: 31 → 31 electrons

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

> Note: Order of filling is 4s before 3d, but write in order of increasing energy levels (so 3d comes after 4s).

So written as:
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p¹

#### Short-hand:
[Ar] 3d¹⁰ 4s² 4p¹

#### Orbital Diagram:
```
1s: ↑↓
2s: ↑↓
2p: ↑↓ ↑↓ ↑↓
3s: ↑↓
3p: ↑↓ ↑↓ ↑↓
3d: ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ (10 electrons)
4s: ↑↓
4p: ↑
```

- 3d: 10 electrons → all paired (5 orbitals × 2 electrons)
- 4s: 2 electrons → paired
- 4p: 1 electron → unpaired

---

6. Krypton (Kr)

- Atomic number: 36 → 36 electrons

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

→ Written in order:
1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s² 4p⁶

#### Short-hand:
[Kr] ← This is itself a noble gas, so short-hand is just [Kr]

But since we’re writing for Kr, it's:
[Kr] or technically [Kr] (no further shorthand)

Wait — actually, Krypton is the noble gas, so its configuration is:

Full: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰ 4p⁶
Short-hand: [Kr] (but since it's Kr, it's just [Kr] — self-referential)

Alternatively, if you're expected to write the previous noble gas, then:

[Ar] 3d¹⁰ 4s² 4p⁶

But usually, for Kr, short-hand = [Kr].

However, in many contexts, they expect [Ar] 3d¹⁰ 4s² 4p⁶ as the short-hand.

So both are acceptable, but standard is:

> Short-hand: [Kr]

But since this is a practice sheet, let's write:

Short-hand: [Ar] 3d¹⁰ 4s² 4p⁶

(As Kr is the next noble gas after Ar, and it's common to use the previous noble gas for shorthand.)

---

✔ Final Answers:

---

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

---

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

---

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

---

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

---

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

---

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

---

📝 Notes:

- Always fill orbitals in order of increasing energy: 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p...
- Use arrows (↑↓) to show electron spin — paired electrons have opposite spins.
- Hund’s Rule: Electrons fill degenerate orbitals (like 2p, 3p, etc.) singly before pairing.
- Pauli Exclusion Principle: No more than 2 electrons per orbital, with opposite spins.

Let me know if you'd like a printable version or visual diagrams!