Atomic structure worksheet - Studocu - Free Printable

The worksheet you've uploaded is titled "Atomic Structure Worksheet", and it appears to be a completed assignment with answers already filled in (in red). Let's go through each question, verify the correctness of the responses, and provide clear explanations for each. This will help reinforce understanding of atomic structure concepts.

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1. Name the three particles of the atom and their respective charges are:

a. Proton – It has positive charge
b. Neutron – It has neutral charge
c. Electron – It has negative charge

✔ Correct!
- Protons are positively charged (+1), located in the nucleus.
- Neutrons have no charge (neutral), also in the nucleus.
- Electrons are negatively charged (-1) and orbit the nucleus.

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2. The number of protons in one atom of an element determines the atom’s ________, and the number of electrons determines ________ of an element.

Answer:
- Atomic number
- The number of shells of an element

⚠️ Partially Correct / Needs Clarification

- ✔ The number of protons determines the atomic number — this is correct.
- ✘ However, the number of electrons does not determine the number of shells.

➡️ Correction:
The number of electrons (in a neutral atom) determines the electron configuration, which determines how many energy levels (shells) are occupied. But more precisely, the principal energy level (shell) is determined by the highest electron shell in the electron configuration.

So, while the idea is close, a better phrasing would be:

> "The number of electrons determines the electron configuration, which determines the number of electron shells."

But since the answer says “the number of shells,” it's acceptable in a simplified context.

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3. The atomic number tells you the number of ________ in one atom of an element. It also tells you the number of ________ in a neutral atom of that element.

Answer:
- Protons
- electrons

✔ Correct!
- Atomic number = number of protons.
- In a neutral atom, number of electrons = number of protons.
- Example: Carbon has atomic number 6 → 6 protons and 6 electrons.

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4. The ________ of an element is the average mass of an element’s naturally occurring atoms, or isotopes, taking into account the ________ of each isotope.

Answer:
- Atomic mass
- Abundance

✔ Correct!
- Atomic mass (also called atomic weight) is a weighted average based on the natural abundance of isotopes.
- For example, chlorine has two isotopes: Cl-35 (~75%) and Cl-37 (~25%). Its atomic mass is ~35.5.

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5. The ________ of an element is the total number of protons and neutrons in the ________ of the atom.

Answer:
- Atomic mass
- nucleus

✘ Incorrect — this is a common confusion.

💡 Explanation:
- The mass number (not atomic mass) is the total number of protons and neutrons in the nucleus.
- Atomic mass is the weighted average of all isotopes' masses, usually not a whole number.

✔ Correct Answer Should Be:
> The mass number of an element is the total number of protons and neutrons in the nucleus of the atom.

So, this question likely had a typo — it should ask for mass number, not atomic mass.

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6. The mass number is used to calculate the number of ________ in one atom of an element. In order to calculate the number of neutrons you must subtract the ________ from the ________.

Answer:
- neutrons
- protons
- atomic mass

✘ Incorrect — again, mixing up mass number and atomic mass.

💡 Correct Explanation:
- To find the number of neutrons:
Number of neutrons = Mass number − Number of protons (atomic number)

So, the correct fill-in should be:
> The mass number is used to calculate the number of neutrons in one atom of an element. In order to calculate the number of neutrons, you must subtract the atomic number from the mass number.

✔ So the corrected version is:
- neutrons
- atomic number
- mass number

Note: The original answer uses "atomic mass" instead of "mass number" — this is a critical error because:
- Mass number is a whole number (e.g., 16 for oxygen).
- Atomic mass is a decimal (e.g., 15.999 for oxygen).

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7. Give the symbol and number of protons in one atom of:

| Element | Symbol | Protons |
|-------------|--------|---------|
| Lithium | Li | 3 |
| Bromine | Br | 35 |
| Iron | Fe | 26 |
| Copper | Cu | 29 |
| Oxygen | O | 8 |
| Mercury | Hg | 80 |
| Arsenic | As | 33 |
| Helium | He | 2 |

✔ All Correct!

These values match the atomic numbers of the elements:
- Li = 3
- Br = 35
- Fe = 26
- Cu = 29
- O = 8
- Hg = 80
- As = 33
- He = 2

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✔ Summary of Corrections:

| Question | Original Answer | Correction Needed? | Corrected Version |
|--------|------------------|--------------------|-------------------|
| 2 | "number of shells" | Partially misleading | Better: "electron configuration" or "electron arrangement" |
| 5 | "Atomic mass" | ✘ Incorrect | Should be "mass number" |
| 6 | "subtract protons from atomic mass" | ✘ Incorrect | Should be: "subtract atomic number from mass number" |

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📝 Final Notes:

- The student did well overall, especially on basic definitions and elemental symbols.
- The main issue is confusing atomic mass and mass number — a very common mistake.
- Emphasize:
- Atomic number = # of protons
- Mass number = protons + neutrons (for a specific isotope)
- Atomic mass = average mass of all isotopes (decimal)

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Let me know if you'd like a revised version of the worksheet with corrections highlighted!