Protons, Neutrons, Electrons, Ions worksheet with answer key.
Educational worksheet: GCSE Atomic Structure Challenge worksheet - Determining numbers of. Download and print for classroom or home learning activities.
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Show Answer Key & Explanations
Step-by-step solution for: GCSE Atomic Structure Challenge worksheet - Determining numbers of
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Show Answer Key & Explanations
Step-by-step solution for: GCSE Atomic Structure Challenge worksheet - Determining numbers of
Let’s go step by step to fill in the table correctly.
We are given some values for each ion or atom:
- Ion Symbol (like Mg², N³⁻, etc.)
- # of Protons
- # of Electrons
- # of Neutrons
- Charge
- Cation or Anion
We need to use these rules:
1. Protons = atomic number → tells us what element it is.
2. Electrons = protons minus charge (if positive) or plus charge (if negative).
- For cations (+ charge): electrons = protons – charge value
- For anions (– charge): electrons = protons + |charge|
3. Neutrons = mass number – protons → but here, we’re often given neutrons and asked to find mass number? Wait — actually, looking at the table, sometimes “# of Neutrons” is blank, so we may need to calculate it from mass number if given… BUT in this table, “Mass Number” isn’t a column! Hmm.
Wait — let me look again.
Actually, in the table, columns are:
- Ion Symbol
- # of Protons
- # of Electrons
- # of Neutrons ← this is sometimes blank
- Charge
- Cation or Anion ← this is sometimes blank
But also, in many rows, “# of Neutrons” is filled in, and sometimes not. And “Charge” is sometimes missing.
Also note: The ion symbol already tells us the charge! For example, Mg²⁺ means charge = +2.
So let’s take row by row.
---
Row 1: Mg²⁺
Given:
- Protons = 12 → that’s magnesium (atomic number 12)
- Electrons = 10 → makes sense: 12 – 2 = 10 (because +2 charge means lost 2 electrons)
- Neutrons = 12 → okay, given
- Charge = ? → should be +2 (from symbol)
- Cation/Anion = Cation (positive ion)
→ So fill Charge = +2, Type = Cation
---
Row 2: N³⁻
Given:
- Protons = 7 → nitrogen
- Electrons = 10 → 7 + 3 = 10 (gained 3 electrons for –3 charge)
- Neutrons = 7 → given
- Charge = ? → –3 (from symbol)
- Type = Anion
→ Fill Charge = –3, Type = Anion
---
Row 3: O²⁻
Given:
- Protons = 8 → oxygen
- Electrons = 10 → 8 + 2 = 10
- Neutrons = 8 → given
- Charge = ? → –2
- Type = Anion
→ Fill Charge = –2, Type = Anion
---
Row 4: P³⁻
Given:
- Protons = 15 → phosphorus
- Electrons = 18 → 15 + 3 = 18
- Neutrons = 16 → given
- Charge = ? → –3
- Type = Anion
→ Fill Charge = –3, Type = Anion
---
Row 5: Cl⁻
Given:
- Protons = 17 → chlorine
- Electrons = 18 → 17 + 1 = 18
- Neutrons = 18 → given
- Charge = ? → –1
- Type = Anion
→ Fill Charge = –1, Type = Anion
---
Row 6: Al³⁺
Given:
- Protons = 13 → aluminum
- Electrons = 10 → 13 – 3 = 10
- Neutrons = 14 → given
- Charge = ? → +3
- Type = Cation
→ Fill Charge = +3, Type = Cation
---
Row 7: Sr²⁺
Given:
- Protons = 38 → strontium
- Electrons = 36 → 38 – 2 = 36
- Neutrons = 50 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 8: Li⁺
Given:
- Protons = 3 → lithium
- Electrons = 2 → 3 – 1 = 2
- Neutrons = 4 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 9: Cl⁻ (again?)
Wait — same as row 5? Let’s check:
Given:
- Protons = 17
- Electrons = 18
- Neutrons = 18
- Charge = ? → –1
- Type = Anion
Same as before → Fill Charge = –1, Type = Anion
---
Row 10: S²⁻
Given:
- Protons = 16 → sulfur
- Electrons = 18 → 16 + 2 = 18
- Neutrons = 16 → given
- Charge = ? → –2
- Type = Anion
→ Fill Charge = –2, Type = Anion
---
Row 11: Fe³⁺
Given:
- Protons = 26 → iron
- Electrons = 23 → 26 – 3 = 23
- Neutrons = 30 → given
- Charge = ? → +3
- Type = Cation
→ Fill Charge = +3, Type = Cation
---
Row 12: Fe²⁺
Given:
- Protons = 26
- Electrons = 24 → 26 – 2 = 24
- Neutrons = 30 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 13: Sn⁴⁺
Given:
- Protons = 50 → tin
- Electrons = 46 → 50 – 4 = 46
- Neutrons = 69 → given
- Charge = ? → +4
- Type = Cation
→ Fill Charge = +4, Type = Cation
---
Row 14: Ti⁴⁺
Given:
- Protons = 22 → titanium
- Electrons = 18 → 22 – 4 = 18
- Neutrons = 26 → given
- Charge = ? → +4
- Type = Cation
→ Fill Charge = +4, Type = Cation
---
Row 15: I⁻
Given:
- Protons = 53 → iodine
- Electrons = 54 → 53 + 1 = 54
- Neutrons = 74 → given
- Charge = ? → –1
- Type = Anion
→ Fill Charge = –1, Type = Anion
---
Row 16: Ag⁺
Given:
- Protons = 47 → silver
- Electrons = 46 → 47 – 1 = 46
- Neutrons = 61 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 17: Mn²⁺
Given:
- Protons = 25 → manganese
- Electrons = 23 → 25 – 2 = 23
- Neutrons = 30 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 18: Sn²⁺
Given:
- Protons = 50 → tin
- Electrons = 48 → 50 – 2 = 48
- Neutrons = 69 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 19: Ba²⁺
Given:
- Protons = 56 → barium
- Electrons = 54 → 56 – 2 = 54
- Neutrons = 81 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 20: Cs⁺
Given:
- Protons = 55 → cesium
- Electrons = 54 → 55 – 1 = 54
- Neutrons = 78 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 21: Ca²⁺
Given:
- Protons = 20 → calcium
- Electrons = 18 → 20 – 2 = 18
- Neutrons = 20 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 22: K⁺
Given:
- Protons = 19 → potassium
- Electrons = 18 → 19 – 1 = 18
- Neutrons = 20 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Now, let’s compile all the missing values into the final answer.
The table has blanks only in “Charge” and “Cation or Anion” columns — all other numbers are given.
So for each row, we fill:
Row 1: Charge = +2, Type = Cation
Row 2: Charge = –3, Type = Anion
Row 3: Charge = –2, Type = Anion
Row 4: Charge = –3, Type = Anion
Row 5: Charge = –1, Type = Anion
Row 6: Charge = +3, Type = Cation
Row 7: Charge = +2, Type = Cation
Row 8: Charge = +1, Type = Cation
Row 9: Charge = –1, Type = Anion
Row 10: Charge = –2, Type = Anion
Row 11: Charge = +3, Type = Cation
Row 12: Charge = +2, Type = Cation
Row 13: Charge = +4, Type = Cation
Row 14: Charge = +4, Type = Cation
Row 15: Charge = –1, Type = Anion
Row 16: Charge = +1, Type = Cation
Row 17: Charge = +2, Type = Cation
Row 18: Charge = +2, Type = Cation
Row 19: Charge = +2, Type = Cation
Row 20: Charge = +1, Type = Cation
Row 21: Charge = +2, Type = Cation
Row 22: Charge = +1, Type = Cation
All match the ion symbols.
Final Answer:
Here is the completed table with filled-in "Charge" and "Cation or Anion" columns:
| Ion Symbol | # of Protons | # of Electrons | # of Neutrons | Charge | Cation or Anion |
|------------|--------------|----------------|---------------|--------|------------------|
| Mg²⁺ | 12 | 10 | 12 | +2 | Cation |
| N³⁻ | 7 | 10 | 7 | –3 | Anion |
| O²⁻ | 8 | 10 | 8 | –2 | Anion |
| P³⁻ | 15 | 18 | 16 | –3 | Anion |
| Cl⁻ | 17 | 18 | 18 | –1 | Anion |
| Al³ | 13 | 10 | 14 | +3 | Cation |
| Sr²⁺ | 38 | 36 | 50 | +2 | Cation |
| Li⁺ | 3 | 2 | 4 | +1 | Cation |
| Cl⁻ | 17 | 18 | 18 | –1 | Anion |
| S²⁻ | 16 | 18 | 16 | –2 | Anion |
| Fe³⁺ | 26 | 23 | 30 | +3 | Cation |
| Fe²⁺ | 26 | 24 | 30 | +2 | Cation |
| Sn⁴⁺ | 50 | 46 | 69 | +4 | Cation |
| Ti⁴⁺ | 22 | 18 | 26 | +4 | Cation |
| I⁻ | 53 | 54 | 74 | –1 | Anion |
| Ag⁺ | 47 | 46 | 61 | +1 | Cation |
| Mn²⁺ | 25 | 23 | 30 | +2 | Cation |
| Sn²⁺ | 50 | 48 | 69 | +2 | Cation |
| Ba²⁺ | 56 | 54 | 81 | +2 | Cation |
| Cs⁺ | 55 | 54 | 78 | +1 | Cation |
| Ca²⁺ | 20 | 18 | 20 | +2 | Cation |
| K⁺ | 19 | 18 | 20 | +1 | Cation |
✔ All charges and types match the ion symbols and electron/proton counts.
We are given some values for each ion or atom:
- Ion Symbol (like Mg², N³⁻, etc.)
- # of Protons
- # of Electrons
- # of Neutrons
- Charge
- Cation or Anion
We need to use these rules:
1. Protons = atomic number → tells us what element it is.
2. Electrons = protons minus charge (if positive) or plus charge (if negative).
- For cations (+ charge): electrons = protons – charge value
- For anions (– charge): electrons = protons + |charge|
3. Neutrons = mass number – protons → but here, we’re often given neutrons and asked to find mass number? Wait — actually, looking at the table, sometimes “# of Neutrons” is blank, so we may need to calculate it from mass number if given… BUT in this table, “Mass Number” isn’t a column! Hmm.
Wait — let me look again.
Actually, in the table, columns are:
- Ion Symbol
- # of Protons
- # of Electrons
- # of Neutrons ← this is sometimes blank
- Charge
- Cation or Anion ← this is sometimes blank
But also, in many rows, “# of Neutrons” is filled in, and sometimes not. And “Charge” is sometimes missing.
Also note: The ion symbol already tells us the charge! For example, Mg²⁺ means charge = +2.
So let’s take row by row.
---
Row 1: Mg²⁺
Given:
- Protons = 12 → that’s magnesium (atomic number 12)
- Electrons = 10 → makes sense: 12 – 2 = 10 (because +2 charge means lost 2 electrons)
- Neutrons = 12 → okay, given
- Charge = ? → should be +2 (from symbol)
- Cation/Anion = Cation (positive ion)
→ So fill Charge = +2, Type = Cation
---
Row 2: N³⁻
Given:
- Protons = 7 → nitrogen
- Electrons = 10 → 7 + 3 = 10 (gained 3 electrons for –3 charge)
- Neutrons = 7 → given
- Charge = ? → –3 (from symbol)
- Type = Anion
→ Fill Charge = –3, Type = Anion
---
Row 3: O²⁻
Given:
- Protons = 8 → oxygen
- Electrons = 10 → 8 + 2 = 10
- Neutrons = 8 → given
- Charge = ? → –2
- Type = Anion
→ Fill Charge = –2, Type = Anion
---
Row 4: P³⁻
Given:
- Protons = 15 → phosphorus
- Electrons = 18 → 15 + 3 = 18
- Neutrons = 16 → given
- Charge = ? → –3
- Type = Anion
→ Fill Charge = –3, Type = Anion
---
Row 5: Cl⁻
Given:
- Protons = 17 → chlorine
- Electrons = 18 → 17 + 1 = 18
- Neutrons = 18 → given
- Charge = ? → –1
- Type = Anion
→ Fill Charge = –1, Type = Anion
---
Row 6: Al³⁺
Given:
- Protons = 13 → aluminum
- Electrons = 10 → 13 – 3 = 10
- Neutrons = 14 → given
- Charge = ? → +3
- Type = Cation
→ Fill Charge = +3, Type = Cation
---
Row 7: Sr²⁺
Given:
- Protons = 38 → strontium
- Electrons = 36 → 38 – 2 = 36
- Neutrons = 50 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 8: Li⁺
Given:
- Protons = 3 → lithium
- Electrons = 2 → 3 – 1 = 2
- Neutrons = 4 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 9: Cl⁻ (again?)
Wait — same as row 5? Let’s check:
Given:
- Protons = 17
- Electrons = 18
- Neutrons = 18
- Charge = ? → –1
- Type = Anion
Same as before → Fill Charge = –1, Type = Anion
---
Row 10: S²⁻
Given:
- Protons = 16 → sulfur
- Electrons = 18 → 16 + 2 = 18
- Neutrons = 16 → given
- Charge = ? → –2
- Type = Anion
→ Fill Charge = –2, Type = Anion
---
Row 11: Fe³⁺
Given:
- Protons = 26 → iron
- Electrons = 23 → 26 – 3 = 23
- Neutrons = 30 → given
- Charge = ? → +3
- Type = Cation
→ Fill Charge = +3, Type = Cation
---
Row 12: Fe²⁺
Given:
- Protons = 26
- Electrons = 24 → 26 – 2 = 24
- Neutrons = 30 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 13: Sn⁴⁺
Given:
- Protons = 50 → tin
- Electrons = 46 → 50 – 4 = 46
- Neutrons = 69 → given
- Charge = ? → +4
- Type = Cation
→ Fill Charge = +4, Type = Cation
---
Row 14: Ti⁴⁺
Given:
- Protons = 22 → titanium
- Electrons = 18 → 22 – 4 = 18
- Neutrons = 26 → given
- Charge = ? → +4
- Type = Cation
→ Fill Charge = +4, Type = Cation
---
Row 15: I⁻
Given:
- Protons = 53 → iodine
- Electrons = 54 → 53 + 1 = 54
- Neutrons = 74 → given
- Charge = ? → –1
- Type = Anion
→ Fill Charge = –1, Type = Anion
---
Row 16: Ag⁺
Given:
- Protons = 47 → silver
- Electrons = 46 → 47 – 1 = 46
- Neutrons = 61 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 17: Mn²⁺
Given:
- Protons = 25 → manganese
- Electrons = 23 → 25 – 2 = 23
- Neutrons = 30 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 18: Sn²⁺
Given:
- Protons = 50 → tin
- Electrons = 48 → 50 – 2 = 48
- Neutrons = 69 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 19: Ba²⁺
Given:
- Protons = 56 → barium
- Electrons = 54 → 56 – 2 = 54
- Neutrons = 81 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 20: Cs⁺
Given:
- Protons = 55 → cesium
- Electrons = 54 → 55 – 1 = 54
- Neutrons = 78 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Row 21: Ca²⁺
Given:
- Protons = 20 → calcium
- Electrons = 18 → 20 – 2 = 18
- Neutrons = 20 → given
- Charge = ? → +2
- Type = Cation
→ Fill Charge = +2, Type = Cation
---
Row 22: K⁺
Given:
- Protons = 19 → potassium
- Electrons = 18 → 19 – 1 = 18
- Neutrons = 20 → given
- Charge = ? → +1
- Type = Cation
→ Fill Charge = +1, Type = Cation
---
Now, let’s compile all the missing values into the final answer.
The table has blanks only in “Charge” and “Cation or Anion” columns — all other numbers are given.
So for each row, we fill:
Row 1: Charge = +2, Type = Cation
Row 2: Charge = –3, Type = Anion
Row 3: Charge = –2, Type = Anion
Row 4: Charge = –3, Type = Anion
Row 5: Charge = –1, Type = Anion
Row 6: Charge = +3, Type = Cation
Row 7: Charge = +2, Type = Cation
Row 8: Charge = +1, Type = Cation
Row 9: Charge = –1, Type = Anion
Row 10: Charge = –2, Type = Anion
Row 11: Charge = +3, Type = Cation
Row 12: Charge = +2, Type = Cation
Row 13: Charge = +4, Type = Cation
Row 14: Charge = +4, Type = Cation
Row 15: Charge = –1, Type = Anion
Row 16: Charge = +1, Type = Cation
Row 17: Charge = +2, Type = Cation
Row 18: Charge = +2, Type = Cation
Row 19: Charge = +2, Type = Cation
Row 20: Charge = +1, Type = Cation
Row 21: Charge = +2, Type = Cation
Row 22: Charge = +1, Type = Cation
All match the ion symbols.
Final Answer:
Here is the completed table with filled-in "Charge" and "Cation or Anion" columns:
| Ion Symbol | # of Protons | # of Electrons | # of Neutrons | Charge | Cation or Anion |
|------------|--------------|----------------|---------------|--------|------------------|
| Mg²⁺ | 12 | 10 | 12 | +2 | Cation |
| N³⁻ | 7 | 10 | 7 | –3 | Anion |
| O²⁻ | 8 | 10 | 8 | –2 | Anion |
| P³⁻ | 15 | 18 | 16 | –3 | Anion |
| Cl⁻ | 17 | 18 | 18 | –1 | Anion |
| Al³ | 13 | 10 | 14 | +3 | Cation |
| Sr²⁺ | 38 | 36 | 50 | +2 | Cation |
| Li⁺ | 3 | 2 | 4 | +1 | Cation |
| Cl⁻ | 17 | 18 | 18 | –1 | Anion |
| S²⁻ | 16 | 18 | 16 | –2 | Anion |
| Fe³⁺ | 26 | 23 | 30 | +3 | Cation |
| Fe²⁺ | 26 | 24 | 30 | +2 | Cation |
| Sn⁴⁺ | 50 | 46 | 69 | +4 | Cation |
| Ti⁴⁺ | 22 | 18 | 26 | +4 | Cation |
| I⁻ | 53 | 54 | 74 | –1 | Anion |
| Ag⁺ | 47 | 46 | 61 | +1 | Cation |
| Mn²⁺ | 25 | 23 | 30 | +2 | Cation |
| Sn²⁺ | 50 | 48 | 69 | +2 | Cation |
| Ba²⁺ | 56 | 54 | 81 | +2 | Cation |
| Cs⁺ | 55 | 54 | 78 | +1 | Cation |
| Ca²⁺ | 20 | 18 | 20 | +2 | Cation |
| K⁺ | 19 | 18 | 20 | +1 | Cation |
✔ All charges and types match the ion symbols and electron/proton counts.
Parent Tip: Review the logic above to help your child master the concept of protons neutrons electrons worksheets.
