How many elements are present in the 6th period of the periodic table?

📚 Chapter: Classification of Elements and Periodicity in Properties

📘 Detailed Solution

🔵 Step 1: Identify the 6th Period

The 6th period is the sixth horizontal row of the modern periodic table.

6th Period → Cs to Rn

🟢 Step 2: Count the Elements

The 6th period contains elements from atomic number 55 to 86.

86 − 55 + 1 = 32 elements

Therefore, the 6th period contains 32 elements.

🎬 6th Period – Element Count

Atomic Number 55 → 86

55
Cs 56
Ba 57
La 58
Ce 59
Pr 60
Nd

⋯

71
Lu 72
Hf 73
Ta 74
W 75
Re 76
Os

⋯

81
Tl 82
Pb 83
Bi 84
Po 85
At 86
Rn

🎯 Total = 32 Elements

🟣 Why does the 6th period contain 32 elements?

The 6th period involves the filling of the 6s, 4f, 5d and 6p subshells.

Subshell	Maximum Electrons
6s	2
4f	14
5d	10
6p	6
Total	32

2 + 14 + 10 + 6 = 32

🟠 Important Point

The Lanthanoids are associated with the 6th period. They are shown separately at the bottom of the periodic table to keep the main table compact.

6th Period → 32 Elements
Lanthanoids → 14 Elements

✅ Final Answer

The 6th period contains 32 elements.

It starts with Cesium (Cs, Z = 55) and ends with Radon (Rn, Z = 86).

📝 20 MCQs with Answers

1. How many elements are present in the 6th period?

A) 8

B) 18

C) 32

D) 36

✅ Answer

C) 32

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2. The 6th period starts with:

A) Rb

B) Cs

C) Ba

D) Fr

✅ Answer

B) Cs

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3. The 6th period ends with:

A) At

B) Xe

C) Rn

D) Og

✅ Answer

C) Rn

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4. The atomic number of Cs is:

A) 54

B) 55

C) 56

D) 57

✅ Answer

B) 55

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5. The atomic number of Rn is:

A) 84

B) 85

C) 86

D) 87

✅ Answer

C) 86

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6. The 6th period belongs to which row?

A) 6th horizontal row

B) 6th vertical column

C) 5th horizontal row

D) 7th horizontal row

✅ Answer

A) 6th horizontal row

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7. Which series is associated with the 6th period?

A) Actinoids

B) Lanthanoids

C) Halogens

D) Noble gases only

✅ Answer

B) Lanthanoids

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8. The 6th period includes the filling of which subshell?

A) 4f

B) 3d

C) 5f

D) 4d only

✅ Answer

A) 4f

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9. Maximum electrons in the 4f subshell are:

A) 2

B) 6

C) 10

D) 14

✅ Answer

D) 14

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10. Which block contributes 14 elements to the 6th period?

A) s-block

B) p-block

C) d-block

D) f-block

✅ Answer

D) f-block

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11. How many s-block elements are present in the 6th period?

A) 2

B) 6

C) 10

D) 14

✅ Answer

A) 2

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12. How many d-block elements are present in the 6th period?

A) 2

B) 10

C) 14

D) 18

✅ Answer

B) 10

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13. How many p-block elements are present in the 6th period?

A) 2

B) 6

C) 10

D) 14

✅ Answer

B) 6

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14. The total number of elements in the 6th period can be calculated as:

A) 2 + 10 + 6

B) 2 + 14 + 10 + 6

C) 14 + 6

D) 2 + 14

✅ Answer

B) 2 + 14 + 10 + 6

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15. Which element has atomic number 57?

A) La

B) Ce

C) Ba

D) Hf

✅ Answer

A) La

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16. Which element has atomic number 72?

A) Ta

B) Hf

C) W

D) Lu

✅ Answer

B) Hf

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17. Which noble gas is present at the end of the 6th period?

A) Xe

B) Rn

C) Kr

D) Og

✅ Answer

B) Rn

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18. The 6th period is called a:

A) Short period

B) Long period

C) Very short period

D) Incomplete period

✅ Answer

B) Long period

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19. The 6th period contains:

A) Only main-group elements

B) s, d, f and p-block elements

C) Only f-block elements

D) Only d-block elements

✅ Answer

B) s, d, f and p-block elements

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20. The correct answer for the number of elements in the 6th period is:

A) 18

B) 24

C) 32

D) 36

✅ Answer

C) 32

Q1. How many elements are present in the 6th period?

Solution: The 6th period contains 32 elements, from Cs (Z = 55) to Rn (Z = 86).

Q2. Why does the 6th period contain 32 elements?

Solution: The 6th period involves the filling of 6s, 4f, 5d and 6p subshells. Their capacities are 2, 14, 10 and 6 respectively.

2 + 14 + 10 + 6 = 32

Q1. Explain the distribution of elements in the 6th period among different blocks.

Block	Number of Elements
s-block	2
f-block	14
d-block	10
p-block	6
Total	32

Q1. Explain why the 6th period is called a long period.

Solution:

1. The 6th period contains 32 elements.
2. It starts with Cs (Z = 55) and ends with Rn (Z = 86).
3. It includes the filling of the 4f subshell.
4. Therefore, it contains more elements than the short periods and is called a long period.

Q1. Describe the 6th period of the modern periodic table.

Solution:

The 6th period starts with Cesium (Cs, Z = 55) and ends with Radon (Rn, Z = 86). It contains a total of 32 elements.

Block	Subshell	Elements
s	6s	2
f	4f	14
d	5d	10
p	6p	6

2 + 14 + 10 + 6 = 32 elements

Q1. Explain in detail why the 6th period contains 32 elements.

Solution:

The number of elements in a period depends upon the number of electrons that can be accommodated in the subshells being filled during that period.

1️⃣ s-block

The 6s subshell can accommodate 2 electrons.

2️⃣ f-block

The 4f subshell can accommodate 14 electrons.

3️⃣ d-block

The 5d subshell can accommodate 10 electrons.

4️⃣ p-block

The 6p subshell can accommodate 6 electrons.

2 + 14 + 10 + 6 = 32 elements

Hence, the 6th period contains 32 elements.

Final Answer: The 6th period has 32 elements, from Cs (Z = 55) to Rn (Z = 86).

🎯 Quick Revision

6th Period = 32 Elements
Starts: Cs (Z = 55)
Ends: Rn (Z = 86)
6s = 2 | 4f = 14 | 5d = 10 | 6p = 6
Total = 2 + 14 + 10 + 6 = 32