We may indicate an ion by placing above it the sign of its electrical charge, one sign for each valency.
"The Mechanism of Life"
Stéphane Leduc
To steal a phrase from chemistry, their "valency" alters.
"An Ocean Tramp"
William McFee
It may be now stated that it has been found by experiment and supported by theory that the clumping power of an ion rises very rapidly with its valency; that is with the number of unit charges associated with it.
"The Birth-Time of the World and Other Scientific Essays"
J. (John) Joly