Introduction
Strontium is a soft, silvery metal that is highly reactive and never occurs in its pure form. It has 14 known isotopes, of which only four are stable (Sr-84, Sr-86, Sr-87 and Sr-88). The most famous form of Strontium is its radioactive isotope Strontium-90, famous for raising alarm in the 1950's and 1960's over the spread of radioactivity after nuclear arms testing. Strontium is one of the Earth's most abundant elements, comprising about 0.04% of the Earth's soil. Strontium is also found in trace amounts in the oceans.
The History of Strontium
Strontium was discovered in 1790 by the Irish chemist Adair Crawford, in the mines near the Scottish town of Strontian (after which the element was named). The element was discovered after Crawford was working with Witherite (BaCO3) and realized that his sample was tainted with an unknown substance which he called “Strontianite”. The element was first isolated by Sir Humphrey Davy in 1808.
Scientific Description of Strontium
|
Strontium |
|
Sr |
|
38 |
|
87.62 |
|
2.6 g/cm3 |
|
38 |
|
38 |
|
50 |
|
|
|
|
|
|
Thermal Properties:
State (at room temperature) |
Solid |
Melting Point |
777 degrees Celsius (1050 K) |
Boiling Point |
1380 degrees Celsius (1653 K) |
Specific Heat Capacity |
0.30 J/(g)(K) |
Heat of Fusion |
8.30 kJ/mol |
Abundance (ppb by weight):
In Soil: |
360,000 ppb |
In Oceans: |
8100 ppb |
In Sun: |
50 ppb |
In Universe: |
40 ppb |
In Humans: |
3.7 ppb |
Isotopes:
Isotope |
|
Sr-80 |
1.77 hours |
Sr-81 |
22.3 minutes |
Sr-83 |
1.4 days |
Sr-84 |
Stable |
Sr-85 |
64.9 days |
Sr-86 |
Stable |
Sr-87 |
Stable |
Sr-88 |
Stable |
|
50.5 days |
Sr-90 |
29.1 years |
Properties of Strontium
Physical Properties:
- Soft, Silvery Metal
- Scores 1.5 on the Mohs Hardness Scale (for comparison, Diamond scores a 10 on the scale).
- Melting Point: 777 degrees Celsius (1050 K)
- Boiling Point: 1380 degrees Celsius (1653 K)
- Readily oxidizes in air
Chemical Properties:
- Highly reactive metal
- Oxidizes quickly in air, so it must be stored in kerosene
- Reacts vigourously in water to produce Hydrogen gas and Strontium Hydroxide
- Sr + H2O --> H2 + SrOH
- When burned, Strontium produces a Crimson flame
- Atomic Charge: 2+
- Electronegativity: 0.89
- Strong Reducing Agent (with both hydrogen and nitrogen)
Strontium Combustion
Strontium in Water
Health Effects of Strontium
Strontium can be both beneficial and harmful to a person's health, depending on the state in which it is found.
If Strontium is found in its natural state (usually within a compound of some sort), it is relativly harmless, and beneficial in some cases. For example, the compound Strontium Lactate was shown in a clinical study to help pain in Osteoporosis patients.
Strontium can also be harmful to your health in its radioactive form. For example, Strontium-90, which has a half-life of almost 30 years, can settle inside a person's bones and may eventually cause cancer.
Technological Applications
Strontium has many diverse applications, including its uses in toothpaste, fireworks and televisions. Here are some of its common uses:
- In Sensodyne toothpaste (Strontium Chloride and Strontium Acetate)
- The crimson colour in fireworks
- Strontium-90 occasionally used in nuclear reactors
- The medical isotope Strontium-90, which is used to treat cancer
- Strontium ions are used in the world's most accurate atomic clock
- Used in the production of cathode ray tubes for colour televisions
Careers Associated With Strontium
- Radiologist- Medical doctors who use radioactive isotopes of Strontium to treat diseases such as cancer and osteoporosis.
- Geologist - Strontium is one of the most abundant elements found on Earth, and can be found in the soil.
- Pyrotechnics Specialist: Strontium salts are used to produce the red colour in fireworks.
- Nuclear Engineer: These engineers design products such as nuclear reactors and radiation machines used in hospitals.










