Periodic Table Trends worksheet for chemistry students to practice identifying element properties.

You’ve uploaded a worksheet titled “Periodic Table Trends”. The task is:
> *For each of the following, circle the correct element.*

There are 16 rows, each with 3 elements and a description. You must choose which element best fits the description.

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Let’s go row by row and explain the correct choice:

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1. Li Si S → metal

- Li (Lithium) is an alkali metal — definitely a metal.
- Si (Silicon) is a metalloid.
- S (Sulfur) is a nonmetal.
✔ Correct answer: Li

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2. N P As → smallest ionization energy

Ionization energy increases up a group and across a period (left to right).
These are all in Group 15. As you go down the group, ionization energy decreases.
So: N > P > As → As has the smallest ionization energy.
✔ Correct answer: As

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3. K Ca Sc → longest atomic mass

Atomic mass increases across a period.
K (39.1), Ca (40.1), Sc (45.0) → Sc has the largest atomic mass.
✔ Correct answer: Sc

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4. S Cl Ar → member of the halogen family

Halogens = Group 17: F, Cl, Br, I, At, Ts
Cl is chlorine → halogen.
S is sulfur (Group 16), Ar is argon (noble gas).
✔ Correct answer: Cl

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5. Al Si P → greatest electron affinity

Electron affinity generally becomes more negative (higher magnitude) from left to right across a period.
P has higher electron affinity than Al or Si.
Actually, among these, Cl has highest, but it's not here. Among Al, Si, P → P has the greatest electron affinity.
*(Note: Electron affinity trends can be tricky — sometimes exceptions occur, but for this level, P > Si > Al)*
✔ Correct answer: P

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6. Ga Al Si → largest atomic radius

Atomic radius decreases across a period, increases down a group.
Ga is below Al → Ga > Al.
Si is to the right of Al → smaller than Al.
So: Ga > Al > Si → Ga has largest radius.
✔ Correct answer: Ga

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7. V Nb Ta → largest atomic number

V (Vanadium) = 23
Nb (Niobium) = 41
Ta (Tantalum) = 73
✔ Correct answer: Ta

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8. Te I Xe → member of noble gases

Noble gases = Group 18: He, Ne, Ar, Kr, Xe, Rn, Og
Xe is xenon → noble gas.
Te = tellurium (metalloid), I = iodine (halogen).
✔ Correct answer: Xe

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9. Si Ge Sn → 4 energy levels

Energy levels = period number.
Si = Period 3 → 3 energy levels
Ge = Period 4 → 4 energy levels
Sn = Period 5 → 5 energy levels
✔ Correct answer: Ge

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10. Li Be B → member of alkali metals

Alkali metals = Group 1: H, Li, Na, K, Rb, Cs, Fr
Li is lithium → alkali metal.
Be = alkaline earth, B = boron group.
✔ Correct answer: Li

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11. As Se Br → 6 valence electrons

Valence electrons = group number for main group elements (Groups 1–2, 13–18).
As = Group 15 → 5 valence e⁻
Se = Group 16 → 6 valence e⁻
Br = Group 17 → 7 valence e⁻
✔ Correct answer: Se

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12. H Li Na → nonmetal?

H is hydrogen — technically a nonmetal (though it behaves weirdly).
Li and Na are metals.
The question says “nonmetal” — only H qualifies.
✔ Correct answer: H

*(Note: Sometimes H is listed separately, but for this context, it’s the only nonmetal.)*

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13. Hg Tl Pb → member of transition metals

Transition metals = Groups 3–12.
Hg (Mercury) = Group 12 → transition metal
Tl (Thallium) = Group 13 → post-transition metal
Pb (Lead) = Group 14 → post-transition metal
✔ Correct answer: Hg

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14. Na Mg Al → electron distribution ending in s¹

Electron configuration:
- Na: [Ne] 3s¹ → ends in s¹ ✔
- Mg: [Ne] 3s² → ends in s²
- Al: [Ne] 3s² 3p¹ → ends in p¹
✔ Correct answer: Na

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15. Pb Bi Po → metalloid

Metalloids: B, Si, Ge, As, Sb, Te, Po (sometimes)
Po (Polonium) is often classified as a metalloid or post-transition metal — it’s borderline.
Bi (Bismuth) = metal
Pb (Lead) = metal
Among these, Po is most commonly considered a metalloid in many curricula.
✔ Correct answer: Po

*(Note: Some sources classify Po as a metal, but for high school level, it’s often grouped with metalloids.)*

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16. B C N → gas at room temperature

At room temp (25°C):
- B = solid
- C = solid (graphite/diamond)
- N = nitrogen gas (N₂) → gas
✔ Correct answer: N

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17. Ca Sc Ti → electron distribution ending in d⁰

This means no electrons in d subshell — i.e., d orbital is empty.
- Ca: [Ar] 4s² → no d electrons → d⁰ ✔
- Sc: [Ar] 4s² 3d¹ → d¹
- Ti: [Ar] 4s² 3d² → d²
✔ Correct answer: Ca

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## ✔ Final Answers (Circled Elements):

1. Li
2. As
3. Sc
4. Cl
5. P
6. Ga
7. Ta
8. Xe
9. Ge
10. Li
11. Se
12. H
13. Hg
14. Na
15. Po
16. N
17. Ca

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## 💡 Summary Tips:
- Use periodic table trends: atomic size, ionization energy, electron affinity, etc.
- Know group names: alkali metals, halogens, noble gases, transition metals.
- Valence electrons = group number (for main groups).
- Electron configuration helps for "ending in..." questions.
- Physical state at room temp: only a few elements are gases (H, N, O, F, Cl, noble gases).

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