Definition

1. Noun:
   • A chemical element: "atomic number 17" is the scientific term for the chemical element with 17 protons in its nucleus. It is a member of the halogen group on the periodic table.
   • A specific substance: In its pure form under standard conditions, it is a dense, yellow-green gas that is highly reactive, toxic, and irritating to the eyes and respiratory system.

Usage Examples

• Noun:
  • The periodic table lists chlorine as atomic number 17.
  • Atomic number 17 is essential for the disinfection of public water supplies.

Advanced Usage

• Scientific Context: The term "atomic number 17" is used primarily in scientific, technical, and educational contexts to specify the element precisely by its fundamental property (proton count), rather than its common name.
  • The isotope of atomic number 17 used in research has a mass number of 37.

Variants and Related Words

• Chlorine (n): The common name for the element with atomic number 17.
  • Chlorine is added to swimming pools to kill bacteria.
• Chlorinate (v): To treat or combine with chlorine.
  • The city will chlorinate the water reservoir.

Synonyms

• Chlorine: The direct and most common synonym for "atomic number 17".

Related Phrases

• Element 17: An alternative numerical designation.
  • The properties of element 17 make it an effective bleach.

Noun

1. a common nonmetallic element belonging to the halogens; best known as a heavy yellow irritating toxic gas; used to purify water and as a bleaching agent and disinfectant; occurs naturally only as a salt (as in sea water)