Black and White photography film is coated with tiny crystals of a metal compound. What is the metal?

-- Caroline McLeary (libra1@btinternet.com), April 20, 2001

Answers

Silver.

-- Scott Walton (f64sw@hotmail.com), April 20, 2001.

Silver Halide, actually, is what it's coated with. This is converted to metallic silver by being exposed to light.

-- Bill Mitchell (bmitch@home.com), April 20, 2001.

Even more precisely, the silver "halide" is bromide or choloride. Halogens are in the 7th column of the periodic table. The silver is reduced by an oxidizing agent to black metallic silver during development. (The nightmare of my college general chemistry and organic chemistry is coming back to haunt me.)

Cheerio

-- floren (flcpge@yahoo.com), April 21, 2001.

Correction, the reduction occurs when light irradiates the silver crystals. The latent image is revealed during the development. My apologies

Cheerio

-- floren (flcpge@yahoo.com), April 21, 2001.