This comprehensive worksheet helps students practice counting atoms in chemical formulas and identifying molecular structures.

The image you've uploaded is a "Counting Atoms & Molecular Models Worksheet" designed for students to practice identifying and counting atoms in chemical formulas and molecular models. It includes two main sections:

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🔬 Part One: Counting Atoms from Chemical Formulas

Students are given the chemical formula of various compounds and asked to:
- Identify the elements present.
- Count how many atoms of each element are in the molecule.

Let’s go through the examples and solve them step by step.

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#### ✔ Example: Sulfuric Acid (H₂SO₄)
- Hydrogen (H): 2 atoms
- Sulfur (S): 1 atom
- Oxygen (O): 4 atoms
✔ So, answer: *Hydrogen - 2, Sulfur - 1, Oxygen - 4*

Now let's solve the rest:

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| Name | Formula | Number of Atoms of Each Element |
|------|--------|-------------------------------|
| Nitric Acid | HNO₃ | Hydrogen - 1, Nitrogen - 1, Oxygen - 3 |
| Acetic Acid (in vinegar) | HC₂H₃O₂ | Let's simplify: C₂H₄O₂ → Carbon - 2, Hydrogen - 4, Oxygen - 2 |
| Sodium Silicate | Na₂SiO₃ | Sodium - 2, Silicon - 1, Oxygen - 3 |
| Water | H₂O | Hydrogen - 2, Oxygen - 1 |
| Vitamin C | C₆H₈O₆ | Carbon - 6, Hydrogen - 8, Oxygen - 6 |
| Aspirin | C₉H₈O₄ | Carbon - 9, Hydrogen - 8, Oxygen - 4 |
| Chloroform | CHCl₃ | Carbon - 1, Hydrogen - 1, Chlorine - 3 |
| Glucose | C₆H₁₂O₆ | Carbon - 6, Hydrogen - 12, Oxygen - 6 |

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🧪 Part Two: Counting Atoms from Molecular Models

This section shows visual diagrams of molecules (using colored spheres for different atoms), and students must:
- Identify the elements (based on color codes or labels).
- Count the number of atoms of each element.
- Write the name of the compound if it’s provided (like sulfuric acid).

Let’s analyze one example from the image:

#### 🔹 First Molecule (shown as O-S-O with OH groups):
This looks like sulfuric acid (H₂SO₄).
- Central S (sulfur) bonded to 4 oxygen atoms.
- Two OH groups = 2 hydrogen atoms.
- Total:
- S: 1
- O: 4
- H: 2

✔ Answer: *Sulfur - 1, Oxygen - 4, Hydrogen - 2* → Sulfuric Acid

#### 🔹 Second Molecule: Na⁺ and O²⁻ with something else?
Looks like sodium oxide or possibly sodium peroxide, but based on the model:
- One Na (sodium), one O, and another O? Possibly Na₂O — but only one Na shown.
Wait — this might be Na₂O or NaO₂ depending on context.

But looking at the next one:
- A model with Mg and three O atoms → likely MgO₃? But that’s not common.
Wait — perhaps it’s Mg(OH)₂? No, there are no H atoms.

Alternatively, maybe it's MgO with extra oxygen?

Actually, this may represent magnesium oxide (MgO) or magnesium peroxide (MgO₂), but without clear bonding, we assume:
- Mg: 1
- O: 3 → Not standard.

Wait — perhaps it's MgCO₃? But no carbon shown.

Looking more carefully: the model shows Mg with three O atoms. That could be MgO₃, but that’s rare.

Alternatively, it might be magnesium carbonate (MgCO₃) — but carbon isn’t labeled.

Possibly a typo or simplified model.

But since the worksheet uses common compounds, perhaps it’s magnesium oxide (MgO) with an error in drawing.

Let’s skip to the last one:

#### 🔹 Last Molecule: H-C-C-Cl with O and H
Structure:
```
H O
| ||
H - C - C - Cl
|
H
```

That’s chloroacetaldehyde? Or chloroacetone?

But simpler: likely chloroethanal or acetyl chloride?

Wait — actually, this looks like acetyl chloride: CH₃COCl

But written as: C₂H₃OCl

Wait — let’s count:
- Left carbon: bonded to 3 H and 1 C → CH₃
- Right carbon: double bond to O, single bond to Cl, single bond to C → COCl
So: CH₃COCl → C₂H₃OCl

Yes! That’s acetyl chloride.

So:
- Carbon: 2
- Hydrogen: 3
- Oxygen: 1
- Chlorine: 1

Name: Acetyl Chloride

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✔ Summary of Solutions

#### Part One – Counting Atoms from Formulas:

| Name | Formula | Elements & Atom Counts |
|------|--------|-------------------------|
| Sulfuric Acid | H₂SO₄ | H:2, S:1, O:4 |
| Nitric Acid | HNO₃ | H:1, N:1, O:3 |
| Acetic Acid | C₂H₄O₂ | C:2, H:4, O:2 |
| Sodium Silicate | Na₂SiO₃ | Na:2, Si:1, O:3 |
| Water | H₂O | H:2, O:1 |
| Vitamin C | C₆H₈O₆ | C:6, H:8, O:6 |
| Aspirin | C₉H₈O₄ | C:9, H:8, O:4 |
| Chloroform | CHCl₃ | C:1, H:1, Cl:3 |
| Glucose | C₆H₁₂O₆ | C:6, H:12, O:6 |

#### Part Two – Molecular Models:

1. Sulfuric Acid (H₂SO₄) → S:1, O:4, H:2 → Sulfuric Acid
2. Na + O (possibly Na₂O?) → If two Na and one O → Na:2, O:1 → Sodium Oxide
- But diagram shows one Na and one O → Maybe NaO? Unlikely.
- Could be sodium superoxide (NaO₂)? But not standard.
- Likely intended: Sodium oxide (Na₂O) — but model shows only one Na and one O → probably a simplification.

3. Mg with three O atoms → Mg:1, O:3 → Not common. Could be magnesium carbonate (MgCO₃) if C is hidden, but no C shown.
- More likely: Magnesium oxide (MgO) — but only one O shown.

4. CH₃COCl (Acetyl Chloride) → C:2, H:3, O:1, Cl:1 → Acetyl Chloride

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💡 Tips for Students:

- Use subscripts to count atoms (e.g., H₂ means 2 hydrogen atoms).
- For polyatomic ions or complex molecules, break down the formula.
- In molecular models:
- Color codes matter (e.g., red = O, blue = N, gray = C, white = H, green = Cl, etc.)
- Count each sphere representing an atom.

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✔ Final Answer:

This worksheet teaches students to:
1. Read chemical formulas and count atoms.
2. Interpret molecular models and deduce elemental composition.
3. Name common compounds based on structure.

You can use this worksheet in printable form or Google Classroom (as indicated at the bottom).

Let me know if you'd like a completed version of the worksheet or help explaining specific molecules!