Periodic Table Basics 2 Worksheet for 7th - 10th Grade | Lesson Planet - Free Printable

Let's go through each question and correct or clarify the answers based on scientific accuracy, since some of the responses in your document contain inaccuracies. I'll explain each one clearly.

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6. What do you notice about the number of valence electrons as you move from left to right across a period (or row) in the periodic table? (Example: Na → Ar)

✔ Correct Answer:
The number of valence electrons increases from left to right across a period.

🔹 Explanation:
As you move from left to right across a period, the number of protons and electrons increases. The electrons fill the outermost energy level (valence shell), so the number of valence electrons increases by one for each element. For example:
- Sodium (Na): 1 valence electron
- Magnesium (Mg): 2
- Aluminum (Al): 3
- ...
- Argon (Ar): 8

So yes, valence electrons increase from left to right.

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7. What do you notice about the number of valence electrons as you move down a group or column in the periodic table? (Example: H, Li, Na)

✘ Incorrect Answer Given: "The valence electrons are increasing from up to down."

✔ Correct Answer:
The number of valence electrons remains the same as you move down a group.

🔹 Explanation:
Elements in the same group have the same number of valence electrons, which is why they have similar chemical properties. For example:
- Hydrogen (H): 1 valence electron
- Lithium (Li): 1 valence electron
- Sodium (Na): 1 valence electron

All alkali metals (Group 1) have 1 valence electron, regardless of their position up or down the group.

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8. What do you notice about the number of energy levels or shells as you move down a group or column in the periodic table? (Example: H, Li, Na)

✔ Correct Answer:
The number of energy levels (electron shells) increases by one as you move down a group.

🔹 Explanation:
Each new period adds a new principal energy level (shell). So:
- Hydrogen (H): 1 shell (n=1)
- Lithium (Li): 2 shells (n=1, n=2)
- Sodium (Na): 3 shells (n=1, n=2, n=3)

Thus, each step down a group adds one more energy level.

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9. What do you notice about the melting points as you move from left to right across a period (or row) in the periodic table? (Example: Li → Ne)

✘ Incorrect Answer Given: "The melting point when they go from left to right it is getting colder, they are negative."

This is not accurate.

✔ Correct Answer:
Melting points generally increase from left to right across a period, but not uniformly, and then decrease sharply toward the noble gases.

🔹 Explanation:
- Metals on the left (e.g., Li, Be) have relatively low melting points.
- As you move toward the center (e.g., B, C, N), metallic bonding strengthens and melting points rise.
- Carbon (C) has an extremely high melting point due to strong covalent bonds in diamond.
- Then, nonmetals like nitrogen (N₂), oxygen (O₂), fluorine (F₂), and neon (Ne) are gases at room temperature with very low melting points.

So, overall trend: Increases to a peak around Group 14, then decreases.

⚠️ Example:
- Li: ~180°C
- Be: ~1287°C
- B: ~2076°C
- C (diamond): ~3550°C
- N₂: -210°C
- O₂: -218°C
- F₂: -219°C
- Ne: -246°C

➡️ So, melting points rise initially, then fall dramatically.

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10. What do you notice about the boiling points as you move from left to right across a period (or row) in the periodic table? (Example: Li → Ne)

✘ Incorrect Answer Given: "The boiling points are getting colder going into the negatives from left to right."

Again, this is misleading.

✔ Correct Answer:
Boiling points generally increase from left to right up to Group 14, then decrease sharply.

🔹 Explanation:
Similar to melting points:
- Metals have higher boiling points due to metallic bonding.
- Carbon (C) has very high boiling point (~4827°C).
- Nonmetals (N₂, O₂, F₂, Ne) are gases with weak intermolecular forces → low boiling points.

So the trend is similar: peaks around carbon, drops off.

Example:
- Li: ~1342°C
- Be: ~2471°C
- B: ~2700°C
- C: ~4827°C
- N₂: -196°C
- O₂: -183°C
- F₂: -188°C
- Ne: -246°C

➡️ So boiling points rise then fall.

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11. Each column or group in the periodic table is called a family. Elements are organized into families according to their physical and chemical properties. Identify the elements that belong to each family based on the number of valence electrons. Give the name and symbol for each element.

Your list here is mostly correct, but let’s clarify:

| Family | Valence Electrons | Elements |
|--------|-------------------|---------|
| Alkali Metals | 1 | Li, Na, K, Rb, Cs, Fr |
| Alkaline Earth Metals | 2 | Be, Mg, Ca, Sr, Ba, Ra |
| Boron Family | 3 | B, Al, Ga, In, Tl |
| Carbon Family | 4 | C, Si, Ge, Sn, Pb |
| Nitrogen Family | 5 | N, P, As, Sb, Bi |
| Oxygen Family | 6 | O, S, Se, Te, Po |
| Halogens | 7 | F, Cl, Br, I, At |
| Noble Gases | 8 (except He = 2) | He, Ne, Ar, Kr, Xe, Rn |

✔ Your list is good — just make sure symbols match correctly (e.g., “A” should be “Al” for aluminum).

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12. What do you notice about the location of the elements in each family?

✔ Correct Answer:
They are all in the same column (group), and thus have similar physical and chemical properties because they have the same number of valence electrons.

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13. How would you classify hydrogen? Give at least one reason.

✔ Answer Given:
“It is a gas, because it is an alkali metal with one valence electron. It feels like Li’s one is a source with fuel cells, power, and heat.”

This is partially correct, but needs clarification.

✔ Better Answer:
Hydrogen is often placed above Group 1 (alkali metals) because it has one valence electron, like lithium (Li), sodium (Na), etc.

However, hydrogen is not a metal — it is a nonmetal and exists as a gas at room temperature.

It behaves differently from other alkali metals:
- It doesn’t form positive ions easily (it can form H⁻ or H⁺).
- It forms covalent bonds (e.g., H₂O, CH₄), unlike metals that form ionic compounds.

So, hydrogen is unique and does not fit perfectly into any group.

🔸 Conclusion:
Hydrogen is usually placed in Group 1 for convenience, but it is not a true alkali metal. Its placement is an exception.

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14. Do any of the elements have similar properties? If yes, list the names of the elements and the properties they have in common.

✔ Yes. Elements in the same group have similar properties.

Examples:
- Lithium (Li), Sodium (Na), Potassium (K): All are soft, shiny metals; react violently with water; form +1 ions; low density.
- Fluorine (F), Chlorine (Cl), Bromine (Br): All are halogens; highly reactive nonmetals; form -1 ions; form acids with hydrogen (HF, HCl, HBr).
- Helium (He), Neon (Ne), Argon (Ar): All are noble gases; unreactive; full valence shells; used in lighting and cryogenics.

🔹 Reason: They have the same number of valence electrons, leading to similar chemical behavior.

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✔ Final Summary of Corrections:

| Question | Original Answer | Corrected Answer |
|--------|------------------|------------------|
| 6 | ✓ | ✓ |
| 7 | ✘ (increasing) | Same number of valence electrons |
| 8 | ✓ | ✓ |
| 9 | ✘ (getting colder) | Increase then decrease |
| 10 | ✘ (getting colder) | Increase then decrease |
| 11 | Mostly ✓ | Ensure correct symbols |
| 12 | ✓ | ✓ |
| 13 | Partially correct | Hydrogen is not an alkali metal; placed in Group 1 due to 1 valence electron, but behaves uniquely |
| 14 | ✓ | Yes, elements in same group have similar properties |

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