Printable chemistry worksheet focusing on periodic trends, including questions about electron affinity, electronegativity, ionization energy, atomic radius, and the differences between metals and nonmetals.

Let's go through the Periodic Trends Worksheet step by step and solve each question with explanations based on periodic trends.

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1. Circle the best answer that has the:

#### a) Smallest electron affinity
Elements: N, P, As, Sb, Bi
- Electron affinity generally increases (becomes more negative) across a period and decreases down a group.
- Nitrogen (N) has very low electron affinity because it has a half-filled p-subshell (stable configuration), so adding an electron is unfavorable.
- So, N has the smallest (least negative) electron affinity.

✔ Answer: N

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#### b) Largest electronegativity
Elements: Ga, Ge, As, Sc
- Electronegativity increases across a period and decreases down a group.
- Among these:
- Ga (Group 13), Ge (14), As (15), Sc (Group 3)
- As is furthest right → highest electronegativity
- Sc is a transition metal and has low electronegativity

✔ Answer: As

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#### c) Largest ionization energy
Elements: O, S, Sc, Te, Po
- Ionization energy increases across a period and decreases down a group.
- O is in Period 2, Group 16 — high IE.
- But Sc is a transition metal (low IE due to shielding).
- Te and Po are heavier → lower IE.
- O has higher IE than S, but note: O < N due to electron repulsion, but among these, O is still higher than S, Sc, etc.
- However, Sc has very low IE (it's a metal).
- The highest IE among these is O, but wait — S is below O, so O > S.
- Actually, O has higher IE than S, Te, Po.
- But Sc is a metal → very low IE.
- So, O has the largest ionization energy here.

✔ Answer: O

> Note: Oxygen has a slightly lower IE than nitrogen due to electron pairing, but it’s still higher than S, Te, Po, and especially Sc.

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#### d) Lowest ionization energy
Elements: O, S, Se, Te, Po
- Ionization energy decreases down a group.
- Po (Polonium) is at the bottom → lowest IE.

✔ Answer: Po

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#### e) Smallest atomic radius
Elements: F, Cl, Br, I, At
- Atomic radius increases down a group.
- F is at the top → smallest radius.

✔ Answer: F

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#### f) Largest atomic radius
Elements: Li, Na, K, Rb, Cs
- All alkali metals, increasing down the group.
- Cs is at the bottom → largest radius.

✔ Answer: Cs

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2. Low ionization energy is a characteristic of a ________

- Low IE means atoms lose electrons easily → typical of metals, especially alkali metals.

✔ Answer: Metal

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3. What does atomic radius measure?

- It measures the distance from the nucleus to the outermost electron shell (or the average distance of valence electrons from the nucleus).

✔ Answer: The size of an atom; the distance from the nucleus to the outermost electrons.

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4. Describe the change in the atomic size across a period and down a group.

- Across a period (left to right): Atomic radius decreases because effective nuclear charge increases, pulling electrons closer.
- Down a group: Atomic radius increases because new electron shells are added, increasing distance from nucleus.

✔ Answer:
> Across a period: atomic radius decreases.
> Down a group: atomic radius increases.

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5. Which element has the largest atomic radius?

- This is a general question. Assuming we’re considering common elements, Cesium (Cs) or Francium (Fr) have the largest atomic radii.
- Since Fr is radioactive and rare, Cs is typically considered the largest stable element.

✔ Answer: Cesium (Cs)

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6. Explain the main difference between metals and nonmetals.

- Metals tend to lose electrons to form cations; they are shiny, malleable, good conductors.
- Nonmetals tend to gain electrons to form anions; they are brittle, poor conductors (except graphite), dull.

✔ Answer: Metals tend to lose electrons and form positive ions, while nonmetals tend to gain electrons and form negative ions.

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7. Determine if the listed pairs of elements have similar or different properties.

| Pair | Similar or Different? | Reason |
|------|------------------------|--------|
| a) Potassium & Rubidium | ✔ Similar | Both alkali metals (Group 1), same chemical behavior |
| b) Calcium & Barium | ✔ Similar | Both alkaline earth metals (Group 2) |
| c) Sodium & Chlorine | ✘ Different | Na is metal, Cl is nonmetal; opposite behaviors |
| d) Helium & Krypton | ✔ Similar | Both noble gases (Group 18), inert |
| e) Phosphorus & Oxygen | ✘ Different | P is nonmetal, O is nonmetal but very reactive; different groups |
| f) Lithium & Fluorine | ✘ Different | Li is metal, F is nonmetal; react vigorously |

✔ Answers:
a) Similar
b) Similar
c) Different
d) Similar
e) Different
f) Different

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8. Which element has the largest electronegativity?

- Electronegativity increases across a period and decreases down a group.
- Fluorine (F) is the most electronegative element (value = 3.98 on Pauling scale).

✔ Answer: Fluorine (F)

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9. Which group (name) would have the lowest ionization energies?

- Alkali metals (Group 1) have the lowest ionization energies because they have one valence electron and large atomic radii.

✔ Answer: Alkali metals

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10. Which group (name) has the highest ionization energies?

- Noble gases (Group 18) have the highest ionization energies because they have full valence shells and are very stable.

✔ Answer: Noble gases

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✔ Final Answers Summary:

1.
a) N
b) As
c) O
d) Po
e) F
f) Cs

2. Metal

3. The distance from the nucleus to the outermost electrons.

4. Atomic radius decreases across a period and increases down a group.

5. Cesium (Cs)

6. Metals lose electrons to form cations; nonmetals gain electrons to form anions.

7.
a) Similar
b) Similar
c) Different
d) Similar
e) Different
f) Different

8. Fluorine (F)

9. Alkali metals

10. Noble gases

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