noun. a radioactive element of the alkali-metal group discovered as a disintegration product of actinium.
- atomic number 87
- francium (French)
- -ium (French)
Example sentences of the word francium
1. Noun, singular or mass
Hypothetically, francium would react explosively with water in a comparable way to caesium but much more quickly.
2. Verb, non-3rd person singular present
This makes francium the most reactive of the alkali metals.