Chemistry worksheet focusing on periodic table facts, including element symbols, atomic numbers, and classification of elements.

Let's solve this step-by-step based on the worksheet titled "Periodic Table Facts".

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Part 1: Identify the symbol for each element

We need to write the chemical symbol for each element listed.

| Number | Element | Symbol |
|--------|---------------|--------|
| 1 | Oxygen | O |
| 2 | Hydrogen | H |
| 3 | Chlorine | Cl |
| 4 | Sodium | Na |
| 5 | Fluorine | F |
| 6 | Carbon | C |
| 7 | Helium | He |
| 8 | Nitrogen | N |
| 9 | Copper | Cu |
| 10 | Sulfur | S |
| 11 | Magnesium | Mg |
| 12 | Manganese | Mn |
| 13 | Neon | Ne |
| 14 | Bromine | Br |
| 15 | Phosphorus | P |
| 16 | Silver | Ag |
| 17 | Lead | Pb |
| 18 | Iron | Fe |
| 19 | Calcium | Ca |
| 20 | Potassium | K |

✔ Answers:
1. O
2. H
3. Cl
4. Na
5. F
6. C
7. He
8. N
9. Cu
10. S
11. Mg
12. Mn
13. Ne
14. Br
15. P
16. Ag
17. Pb
18. Fe
19. Ca
20. K

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Part 2: Fill in the chart

We are given a table with some entries and need to complete it.

| Element | Symbol | Atomic Number | Period | Group |
|----------|--------|----------------|--------|-------|
| Sodium | Na | 11 | 3 | 1 |
| O | | | | |
| Krypton | | | | |
| | | 79 | | |
| | | | 4 | 7 |

Let’s go row by row.

#### Row 1: Already completed → Sodium (Na, 11, Period 3, Group 1)

#### Row 2: Element is O (Oxygen)
- Symbol: O
- Atomic number: 8
- Period: 2
- Group: 16 (Oxygen is in group 16, also known as chalcogens)

So:
- Element: Oxygen
- Symbol: O
- Atomic Number: 8
- Period: 2
- Group: 16

#### Row 3: Element is Krypton
- Symbol: Kr
- Atomic number: 36
- Period: 4
- Group: 18 (Noble gases)

So:
- Element: Krypton
- Symbol: Kr
- Atomic Number: 36
- Period: 4
- Group: 18

#### Row 4: Atomic number = 79
- Element: Gold (Au)
- Symbol: Au
- Period: 6
- Group: 11

So:
- Element: Gold
- Symbol: Au
- Atomic Number: 79
- Period: 6
- Group: 11

#### Row 5: Period = 4, Group = 7
- This is Manganese (Mn)
- Atomic number: 25
- Symbol: Mn

So:
- Element: Manganese
- Symbol: Mn
- Atomic Number: 25
- Period: 4
- Group: 7

✔ Completed Table:

| Element | Symbol | Atomic Number | Period | Group |
|----------|--------|----------------|--------|-------|
| Sodium | Na | 11 | 3 | 1 |
| Oxygen | O | 8 | 2 | 16 |
| Krypton | Kr | 36 | 4 | 18 |
| Gold | Au | 79 | 6 | 11 |
| Manganese| Mn | 25 | 4 | 7 |

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Part 3: Give an atom with the following characteristics

We need to give one example of an element that fits each category.

| Letter | Category | Example Element | Reasoning |
|--------|------------------------|------------------|---------|
| a | Halogen | Cl (Chlorine) | Group 17 elements (F, Cl, Br, I, At) |
| b | Chalcogen | S (Sulfur) | Group 16 elements (O, S, Se, Te, Po) |
| c | Alkali metal | Na (Sodium) | Group 1 metals (Li, Na, K, Rb, Cs, Fr) |
| d | Actinide series | U (Uranium) | Elements from atomic numbers 89–103 (e.g., U, Pu, Am) |
| e | Lanthanide series | Ce (Cerium) | Elements from atomic numbers 57–71 (e.g., La, Ce, Nd) |
| f | Alkaline Earth metal | Ca (Calcium) | Group 2 metals (Be, Mg, Ca, Sr, Ba, Ra) |
| g | Transition metal | Fe (Iron) | Elements in groups 3–12 (e.g., Fe, Cu, Cr, Ni) |
| h | Nobel gas | Ne (Neon) | Group 18 elements (He, Ne, Ar, Kr, Xe, Rn) |

✔ Answers:
a) Cl
b) S
c) Na
d) U
e) Ce
f) Ca
g) Fe
h) Ne

(Note: Any valid example from the category is acceptable.)

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✔ Final Answer Summary

#### Part 1: Symbols
1. O
2. H
3. Cl
4. Na
5. F
6. C
7. He
8. N
9. Cu
10. S
11. Mg
12. Mn
13. Ne
14. Br
15. P
16. Ag
17. Pb
18. Fe
19. Ca
20. K

#### Part 2: Chart
| Element | Symbol | Atomic Number | Period | Group |
|----------|--------|----------------|--------|-------|
| Sodium | Na | 11 | 3 | 1 |
| Oxygen | O | 8 | 2 | 16 |
| Krypton | Kr | 36 | 4 | 18 |
| Gold | Au | 79 | 6 | 11 |
| Manganese| Mn | 25 | 4 | 7 |

#### Part 3: Characteristics
a) Cl
b) S
c) Na
d) U
e) Ce
f) Ca
g) Fe
h) Ne

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