Tonight’s Sights Brought to You By — Chemicals

By A.J. Hostetler, Richmond Times-Dispatch, Va.

Jul. 4–Necks craning tonight to watch fireworks across Virginia will see a dazzling display of chemistry in celebration of Independence Day.

Fireworks, which began more than 1,000 years ago in Asia as noisemakers, were eventually paired with colors. They were first limited to a dull yellow-orange, but advances in chemistry made colors across the spectrum possible. Even blue, one of the more difficult colors to make, is now commonly found exploding in a starry palm or chrysanthemum.

The vivid shades that explode in the night sky result from metals typically combined with other elements that blaze at different wavelengths. Longer visible wavelengths tend toward the red end of the spectrum and the shortest, violet.

Here’s a guide to the main chemicals that produce the colorful spectacle:

RED: strontium, lithium

ORANGE: calcium

YELLOW: sodium

GREEN: barium

BLUE: copper

PURPLE: a mix of strontium and copper

WHITE: magnesium

SILVER: aluminum, titanium or magnesium

These chemicals create special effects:

Aluminum: silver-and-white flames and sparks

Iron: sparks

Magnesium: white sparks and brilliance

Antimony: glitter

Titanium: silver sparks.

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Copyright (c) 2007, Richmond Times-Dispatch, Va.

Distributed by McClatchy-Tribune Information Services.

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