Isotope GEN CHEM - Isotope Practice Worksheet Here are three ... - Free Printable

It looks like you've uploaded an Isotope Practice Worksheet with several problems related to isotopes, atomic structure, and calculating relative atomic masses. I'll go through each question carefully, explain the solutions, and correct any errors or inconsistencies in the provided answers.

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Problem 1: Isotopes of Carbon

Given isotopes:
- \( ^{12}_{6}\text{C} \)
- \( ^{13}_{6}\text{C} \)
- \( ^{14}_{6}\text{C} \)

#### a. The element is: Carbon ✔
✔️ Correct — all three isotopes have atomic number 6, which corresponds to carbon.

#### b. The number 6 refers to the atomic number ✔
✔️ Correct — the atomic number indicates the number of protons.

#### c. The numbers 12, 13, and 14 refer to the mass number ✔
✔️ Correct — the mass number is the total number of protons and neutrons.

#### d. How many protons and neutrons are in the first isotope?
- Isotope: \( ^{12}_{6}\text{C} \)
- Protons = atomic number = 6
- Neutrons = mass number – protons = 12 – 6 = 6

✘ Incorrect answer given: "12"
👉 Should be: 6 protons and 6 neutrons

#### e. Second isotope: \( ^{13}_{6}\text{C} \)
- Protons = 6
- Neutrons = 13 – 6 = 7

✘ Answer given: "13"
👉 Should be: 6 protons and 7 neutrons

#### f. Third isotope: \( ^{14}_{6}\text{C} \)
- Protons = 6
- Neutrons = 14 – 6 = 8

✘ Answer given: "14"
👉 Should be: 6 protons and 8 neutrons

✔ Corrected Answers:
- d. 6 protons, 6 neutrons
- e. 6 protons, 7 neutrons
- f. 6 protons, 8 neutrons

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Problem 2: Complete the Table

| Isotope name | Atomic no | Mass no | No of protons | No of neutrons | No of electrons |
|------------------|-----------|---------|---------------|----------------|-----------------|
| uranium-235 | 92 | 235 | 92 | 143 | 92 |
| uranium-238 | 92 | 238 | 92 | 146 | 92 |
| boron-10 | 5 | 10 | 5 | 5 | 5 |
| boron-11 | 5 | 11 | 5 | 6 | 5 |

✔ All entries are correct.

- For neutral atoms:
- Number of protons = atomic number
- Number of electrons = number of protons
- Number of neutrons = mass number – atomic number

✔️ Verified:
- Uranium-235: 235 – 92 = 143 neutrons
- Uranium-238: 238 – 92 = 146 neutrons
- Boron-10: 10 – 5 = 5 neutrons
- Boron-11: 11 – 5 = 6 neutrons

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Problem 3: Relative Atomic Mass of Chlorine

Chlorine has two isotopes:
- \( ^{35}\text{Cl} \): abundance = 75%, mass = 35
- \( ^{37}\text{Cl} \): abundance = 25%, mass = 37

Relative atomic mass = (abundance₁ × mass₁) + (abundance₂ × mass₂)

\[
= (0.75 \times 35) + (0.25 \times 37)
= 26.25 + 9.25 = 35.5
\]

✔ Answer: 35.5 ✔️

But note: The problem says “calculate the relative atomic mass of strontium”, but it gives data for chlorine!

✘ This is a mistake in the question.

Strontium is a different element (Sr, atomic number 38), and its isotopes are not mentioned here.

So, the correct interpretation is:

> "Calculate the relative atomic mass of chlorine."

✔ Final answer: 35.5 (correctly calculated, but mislabeled as strontium)

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Problem 4: Relative Atomic Mass of Boron

Boron has:
- Boron-10: mass = 10, abundance = 18.7% = 0.187
- Boron-11: mass = 11, abundance = 81.3% = 0.813

\[
\text{Relative atomic mass} = (0.187 \times 10) + (0.813 \times 11)
= 1.87 + 8.943 = 10.813
\]

✔ Answer: 10.813 ✔️

This matches the given answer.

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✔ Summary of Corrections and Explanations:

| Question | Given Answer | Correct Answer | Explanation |
|--------|--------------|----------------|-------------|
| 1d | 12 | 6 protons, 6 neutrons | Misinterpreted; must separate protons and neutrons |
| 1e | 13 | 6 protons, 7 neutrons | Same error |
| 1f | 14 | 6 protons, 8 neutrons | Same error |
| 3 | 35.5 | 35.5 | Calculation correct, but question incorrectly says "strontium" instead of "chlorine" |

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🟩 Final Corrected Answers:

#### 1.
a. Carbon
b. Atomic number
c. Mass number
d. 6 protons, 6 neutrons
e. 6 protons, 7 neutrons
f. 6 protons, 8 neutrons

#### 2. Table is correct as filled.

#### 3. Relative atomic mass of chlorine = 35.5
(Not strontium — that's a typo in the question.)

#### 4. Relative atomic mass of boron = 10.813 ✔

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