Welcome, loading...
eMusic Study Pack • Chemistry
Student
📖 Comprehensive Note
Atomicity — the number of atoms present in one molecule of a substance. It tells you how many atoms are bonded together to form a single molecule.
- Monatomic: molecules consisting of a single atom (atomicity = 1). Example: Helium (He).
- Diatomic: molecules with two atoms (atomicity = 2). Common examples: H₂, O₂, N₂, Cl₂.
- Triatomic: molecules with three atoms (atomicity = 3). Example: O₃ (ozone).
- Polyatomic: molecules with many atoms (atomicity > 3). Examples: S₈ (atomicity = 8), glucose C₆H₁₂O₆ (atomicity = 24).
- How to calculate: Sum the atoms of each element in the formula. E.g., CH₄ → 1C + 4H = 5 (atomicity 5).
Atomicity is a simple but useful concept for counting atoms within molecular formulas. It is different from valency and molecular mass.
🎤 Lyrics
Verse 1
Helium stands alone, that’s one, monatomic,
Oxygen and hydrogen, in pairs, diatomic.
Ozone has three, that’s triatomic flow,
Phosphorus has four, now you really know.
Chorus
Atomicity, is the number,
of atoms present, in one molecule.
Atomicity, is the number,
of atoms present, in one molecule.
Verse 2
Sulphur comes as eight, polyatomic chain,
Glucose twenty-four, in a molecule’s domain.
Methane is five, ammonia counts four,
Atomicity explains, what molecules store.
Chorus
Atomicity, is the number,
of atoms present, in one molecule.
Atomicity, is the number,
of atoms present, in one molecule.
Outro
So remember when you see a formula’s face,
Atomicity tells the atoms in place.
From one to many, the rule is clear,
Atomicity’s the chorus we’ll always hear.
Chorus
Atomicity, is the number,
of atoms present, in one molecule.
Atomicity, is the number,
of atoms present, in one molecule.
0:00
0:00
📊 Line-by-Line Study Guide
| Lyric Line | Explanation |
|---|---|
| Atomicity is the number of atoms present in one molecule | Definition — count all atoms in the molecular formula to get atomicity. |
| Helium stands alone, that’s one, monatomic | Helium (He) in gas form exists as single atoms; atomicity = 1. |
| Oxygen and hydrogen, in pairs, diatomic | Common elemental gases like O₂ and H₂ have two atoms per molecule; atomicity = 2. |
| Ozone has three, that’s triatomic | Ozone (O₃) is made of three oxygen atoms; atomicity = 3. |
| Phosphorus has four | White phosphorus commonly occurs as P₄ molecules; atomicity = 4 (depends on allotrope). |
| Sulphur comes as eight | Elemental sulfur commonly forms S₈ rings; atomicity = 8 for that allotrope. |
| Glucose twenty-four | Glucose formula C₆H₁₂O₆ → 6 + 12 + 6 = 24 atoms per molecule. |
| Methane is five, ammonia counts four | CH₄ → 1 + 4 = 5; NH₃ → 1 + 3 = 4 (atomicity calculated by summation). |
💡 Mnemonic
"Count Every Atom" — when you see a formula, add up all atomic subscripts to get atomicity.
❓ Quiz
1. What is atomicity?
2. What is the atomicity of O₂?
3. Calculate atomicity of C₆H₁₂O₆ (glucose).
4. Which is monatomic?
5. Atomicity of CH₄ (methane) is:
6. Many elemental sulfur samples are S₈. What is the atomicity?
7. Which molecule is triatomic?
8. If a molecule formula is P₄, its atomicity is:
9. Atomicity is calculated by:
10. What is the atomicity of NH₃ (ammonia)?
🃏 Flashcards
Q1: What is atomicity?
The number of atoms present in one molecule of a substance.
Q2: Atomicity of H₂?
2 (diatomic).
Q3: Atomicity of O₃ (ozone)?
3 (triatomic).
Q4: How to find atomicity from formula?
Add up the subscripts of all atoms in the molecular formula.
Q5: Atomicity of He?
1 (monatomic: He exists as single atoms).
Q6: Atomicity of CH₄?
5 (1 C + 4 H).
Q7: Atomicity of NH₃?
4 (1 N + 3 H).
Q8: Atomicity of glucose C₆H₁₂O₆?
24 (6 + 12 + 6).
Q9: Sulfur common allotrope S₈ atomicity?
8.
Q10: Is atomicity the same as valency?
No — atomicity counts atoms in a molecule; valency describes bonding capacity of an element.
🎯 Drag & Drop
Match each molecule (left) with its atomicity (right). Drag the molecule into the correct box.
Molecules
He
O₂
O₃
CH₄
NH₃
C₆H₁₂O₆
S₈
Atomicity
1
2
3
5
4
24
8
Tip: Drag "C₆H₁₂O₆" to "24", "CH₄" to "5", and "He" to "1".
📌 Summary
- Atomicity = total number of atoms in one molecule. Compute by adding subscripts in the formula.
- Examples: monatomic (He = 1), diatomic (O₂ = 2), triatomic (O₃ = 3), polyatomic (S₈ = 8, C₆H₁₂O₆ = 24).
- Atomicity is a straightforward count — useful for basic molecular questions and classification.