Strontium

This week's element is the alkaline earth metal, strontium, which has the atomic symbol Sr and the atomic number 38. Strontium is a soft silver-white or yellowish (when oxidised) metallic element that is even more chemically reactive than its "little sister", calcium. If you drop strontium into water, for example, it will react vigorously to produce strontium hydroxide and hydrogen gas. Finely powdered strontium metal ignites spontaneously in air at room temperature. But most of us are familiar with strontium because strontium salts are commonly used in fireworks and flares to give a bright (some might say blinding) red color to flames.

Strontium is the 15th most abundant element on Earth, but because of its reactivity, strontium is not found roaming freely in the wild: it occurs in minerals, mostly in strontianite and celestite. In fact, strontium was given its name in honour of the Scottish village, Strontian (Gaelic; Sron an t-Sithein) after it was discovered in ores taken from the local lead mines. Some of you may be amused to learn that the village name translates as "Nose of the Fairies" -- "nose" not being literal, of course; instead it refers to a geographical feature, like a peak.

Because its nucleus is very nearly the same size as that of its "little sister", calcium, the body mistakenly takes up strontium and incorporates it into bones and tooth enamel in the place of calcium. Surprisingly, this is not a health problem and in fact, it can provide a health benefit. For example, in clinical trials, the drug strontium ranelate was found to aid bone growth, increase bone density, and lessen vertebral, peripheral, and hip fractures in women.

However, strontium also has a sinister side, thanks to the ruthless human war machine. The radioactive isotope, ⁹⁰Sr, is common in radioactive fallout. Since radioactive fallout doesn't respect national borders, it falls upon all living things regardless of nationality or species, contaminating water, food and even the air that we all breathe. This isotope is quite dangerous and can cause a variety of leukæmias, bone cancer and other debilitating bone diseases. Perhaps ironically, Strontium-90 is also used to treat cancer. (Strontium-89, an artificial radioisotope, is used specifically to treat bone cancer.)

But the sad fact is that we all are radioactive, some of us moreso than others, as our favourite (radioactive) professor points out in the video embedded below. Radioactive strontium has a half-life of 28.90 years. Thus, everything -- yes, including people -- that was born during that prolonged penis-waving era of nuclear weapons testing is more radioactive than those creatures and plants born before or since. But since then, the Chernobyl and Fukushima nuclear reactor accidents have contaminated huge areas with a number of dangerous radioisotopes, including strontium-90. For example, in the aftermath of the Fukushima Daiichi reactor accident, seawater in the area has been found to have 240 times the legal concentration limit of strontium-90, and of course, this is contaminating local marine life, with predictable consequences.

On that cheery note, I guess you wish to watch the video:

Visit periodicvideos's YouTube channel [video link].

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Video journalist Brady Haran is the man with the camera and the University of Nottingham is the place with the chemists. You can follow Brady on twitter @periodicvideos and the University of Nottingham on twitter @UniNottingham

You've already met these elements:

Rubidium: Rr, atomic number 37
Krypton: Kr, atomic number 36
Bromine: Br, atomic number 35
Selenium: Se, atomic number 34
Arsenic: As, atomic number 33
Germanium: Ge, atomic number 32
Gallium: Ga, atomic number 31
Zinc: Zn, atomic number 30
Copper: Cu, atomic number 29
Nickel: Ni, atomic number 28
Cobalt: Co, atomic number 27
Iron: Fe, atomic number 26
Manganese: Mn, atomic number 25
Chromium: Cr, atomic number 24
Vanadium: V, atomic number 23
Titanium: Ti, atomic number 22
Scandium: Sc, atomic number 21
Calcium: Ca, atomic number 20
Potassium: K, atomic number 19
Argon: Ar, atomic number 18
Chlorine: Cl, atomic number 17
Sulfur: S, atomic number 16
Phosphorus: P, atomic number 15
Silicon: Si, atomic number 14
Aluminium: Al, atomic number 13
Magnesium: Mg, atomic number 12
Sodium: Na, atomic number 11
Neon: Ne, atomic number 10
Fluorine: F, atomic number 9
Oxygen: O, atomic number 8
Nitrogen: N, atomic number 7
Carbon: C, atomic number 6
Boron: B, atomic number 5
Beryllium: Be, atomic number 4
Lithium: Li, atomic number 3
Helium: He, atomic number 2
Hydrogen: H, atomic number 1

Here's a wonderful interactive Periodic Table of the Elements that is just really really fun to play with!

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