Free Printable Atomic Structure Worksheets - Free Printable

Let’s go step by step to solve each part of this worksheet.

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Part 1: Label the parts of an atom and answer charge questions

First, look at the diagram (even though we can’t see it, we know what a basic atom looks like):

- The center is the nucleus, which contains protons and neutrons.
- Electrons orbit around the nucleus in shells or rings.

So for labeling:

→ The dots on the outer rings are electrons.
→ The cluster in the middle is the nucleus.
→ Inside the nucleus, you have protons (usually marked with +) and neutrons (no charge).

Now answer the questions:

a) Proton charge → positive (+)
b) Neutron charge → neutral (no charge / 0)
c) Electron charge → negative (-)
d) Particles in the nucleus → protons and neutrons

✔ All correct based on standard atomic structure.

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Part 2: Fill in #P, #N, #E for Carbon, Neon, Potassium

We use the example given for Oxygen:

- Atomic Number = number of protons (#P)
- In a neutral atom, #E = #P
- Mass Number ≈ average atomic mass rounded to nearest whole number → then #N = Mass Number - #P

Let’s do each element:

Carbon (C):
- Atomic Number = 6 → #P = 6
- Neutral atom → #E = 6
- Average atomic mass = 12.011 → round to 12 → Mass Number = 12
- #N = 12 - 6 = 6

→ #P = 6, #N = 6, #E = 6

Neon (Ne):
- Atomic Number = 10 → #P = 10
- #E = 10 (neutral)
- Mass = 20.108 → round to 20
- #N = 20 - 10 = 10

→ #P = 10, #N = 10, #E = 10

Potassium (K):
- Atomic Number = 19 → #P = 19
- #E = 19 (neutral)
- Mass = 39.098 → round to 39
- #N = 39 - 19 = 20

→ #P = 19, #N = 20, #E = 19

✔ All calculations checked — rounding is appropriate here since these are introductory problems.

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Part 3: Complete the table using periodic table knowledge

Remember:

- Atomic Number = #Protons
- For neutral atoms: #Electrons = #Protons
- Mass Number = #Protons + #Neutrons → so #Neutrons = Mass Number - #Protons
- Symbol comes from periodic table based on atomic number

Let’s fill row by row:

Row 1: Na (Sodium)
- Given: #Protons = 11 → Atomic Number = 11
- #Neutrons = 12 → Mass Number = 11 + 12 = 23
- #Electrons = 11 (neutral)

→ Symbol: Na, Atomic Number: 11, Mass Number: 23, #Protons: 11, #Electrons: 11, #Neutrons: 12

Row 2: K (Potassium)
- Given: Mass Number = 39, #Electrons = 19 → so #Protons = 19 → Atomic Number = 19
- #Neutrons = 39 - 19 = 20

→ Symbol: K, Atomic Number: 19, Mass Number: 39, #Protons: 19, #Electrons: 19, #Neutrons: 20

Row 3: ? , #Protons = 38, #Neutrons = 50
- Atomic Number = 38 → Element is Strontium (Sr)
- Mass Number = 38 + 50 = 88
- #Electrons = 38 (neutral)

→ Symbol: Sr, Atomic Number: 38, Mass Number: 88, #Protons: 38, #Electrons: 38, #Neutrons: 50

Row 4: F (Fluorine)
- Given: #Electrons = 9 → #Protons = 9 → Atomic Number = 9
- #Neutrons = 10 → Mass Number = 9 + 10 = 19

→ Symbol: F, Atomic Number: 9, Mass Number: 19, #Protons: 9, #Electrons: 9, #Neutrons: 10

Row 5: ? , Atomic Number = 20, Mass Number = 40, #Electrons = 20
- Atomic Number 20 → Calcium (Ca)
- #Protons = 20
- #Neutrons = 40 - 20 = 20

→ Symbol: Ca, Atomic Number: 20, Mass Number: 40, #Protons: 20, #Electrons: 20, #Neutrons: 20

Row 6: ? , Atomic Number = 50, #Electrons = 50, #Neutrons = 69
- Atomic Number 50 → Tin (Sn)
- #Protons = 50
- Mass Number = 50 + 69 = 119

→ Symbol: Sn, Atomic Number: 50, Mass Number: 119, #Protons: 50, #Electrons: 50, #Neutrons: 69

Row 7: I (Iodine), Atomic Number = 53, Mass Number = 127
- #Protons = 53
- #Electrons = 53 (neutral)
- #Neutrons = 127 - 53 = 74

→ Symbol: I, Atomic Number: 53, Mass Number: 127, #Protons: 53, #Electrons: 53, #Neutrons: 74

✔ Double-checked all rows — symbols match atomic numbers, math adds up.

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Final Answer:

Part 1:
a) positive
b) no charge (or neutral)
c) negative
d) protons and neutrons

*(Diagram labels: outer dots = electrons; center cluster = nucleus; inside nucleus: protons and neutrons)*

Part 2:
Carbon: #P = 6, #N = 6, #E = 6
Neon: #P = 10, #N = 10, #E = 10
Potassium: #P = 19, #N = 20, #E = 19

Part 3 Table:

| Symbol | Atomic Number | Mass Number | Number of Protons | Number of Electrons | Number of Neutrons |
|--------|---------------|-------------|-------------------|---------------------|--------------------|
| Na | 11 | 23 | 11 | 11 | 12 |
| K | 19 | 39 | 19 | 19 | 20 |
| Sr | 38 | 88 | 38 | 38 | 50 |
| F | 9 | 19 | 9 | 9 | 10 |
| Ca | 20 | 40 | 20 | 20 | 20 |
| Sn | 50 | 119 | 50 | 50 | 69 |
| I | 53 | 127 | 53 | 53 | 74 |