Name a chemical element with a one-letter symbol.

Points are editorial tiers. The source supports membership in the set, not how many people know an answer.

Hydrogen 25 · Familiar

Hydrogen is in the 14-answer set defined by this question.

Also accepted: H

Oxygen 25 · Familiar

Oxygen is in the 14-answer set defined by this question.

Also accepted: O

Carbon 25 · Familiar

Carbon is in the 14-answer set defined by this question.

Also accepted: C

Nitrogen 25 · Familiar

Nitrogen is in the 14-answer set defined by this question.

Also accepted: N

Sulfur 50 · Less common

Sulfur is in the 14-answer set defined by this question.

Also accepted: S · Sulphur

Phosphorus 50 · Less common

Phosphorus is in the 14-answer set defined by this question.

Also accepted: P

Potassium 50 · Less common

Potassium is in the 14-answer set defined by this question.

Also accepted: K

Boron 75 · Uncommon

Boron is in the 14-answer set defined by this question.

Also accepted: B

Fluorine 75 · Uncommon

Fluorine is in the 14-answer set defined by this question.

Also accepted: F

Iodine 75 · Uncommon

Iodine is in the 14-answer set defined by this question.

Also accepted: I

Uranium 100 · Rare

Uranium is in the 14-answer set defined by this question.

Also accepted: U

Tungsten 100 · Rare

Tungsten is in the 14-answer set defined by this question.

Also accepted: W

Vanadium 100 · Rare

Vanadium is in the 14-answer set defined by this question.

Also accepted: V

Yttrium 100 · Rare

Yttrium is in the 14-answer set defined by this question.

Also accepted: Y

Checked exclusions

• Iron: Iron's symbol is Fe, which has two letters.
• Helium: Helium's symbol is He, which has two letters.