atomic number

noun

Definition of atomic number

: an experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines the place of the element in the periodic table — see Chemical Elements Table

Recent Examples of atomic number from the Web

These example sentences are selected automatically from various online news sources to reflect current usage of the word 'atomic number.' Views expressed in the examples do not represent the opinion of Merriam-Webster or its editors. Send us feedback.

First Known Use of atomic number

1913


Medical Dictionary

atomic number

noun atomic num·ber \ -ˈnəm-bər \

medical Definition of atomic number

: an experimentally determined number characteristic of a chemical element that represents the number of protons in the nucleus which in a neutral atom equals the number of electrons outside the nucleus and that determines the place of the element in the periodic table — see Chemical Elements Table

Learn More about atomic number


Seen and Heard

What made you want to look up atomic number? Please tell us where you read or heard it (including the quote, if possible).

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!

WORD OF THE DAY

investment of mental or emotional energy

Get Word of the Day daily email!

Test Your Vocabulary

Odd Habits and Quirks Quiz

  • image1926873504
  • Which of the following best describes an easily irritated person?
Spell It

Can you spell these 10 commonly misspelled words?

TAKE THE QUIZ
Citation

Test Your Knowledge - and learn some interesting things along the way.

TAKE THE QUIZ

Love words? Need even more definitions?

Subscribe to America's largest dictionary and get thousands more definitions and advanced search—ad free!