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Californium is a synthetic radioactive element located at the bottom row of the periodic table.
- It was discovered in 1950 by bombarding curium with alpha particles (helium nuclei) at the University of California Radiation Laboratory in Berkeley.
- Pure californium metal is silvery-white in color and soft enough to be cut with a razor blade.
- The first experiments with concentrated californium began in 1958.
- Since then, 20 californium isotopes with mass numbers ranging from 237 to 256 have been identified.
- Californium-252, one of these isotopes, was originally isolated from a neutron-irradiated sample of plutonium-239.
- Californium-252 is extremely uncommon since it is a synthetic element that cannot be found in nature.
- It is produced by neutron bombardment in high-flux isotope reactors or particle accelerators.
| Table of Content |
Key Terms: Californium, Periodic table, Synthetic element, Particle accelerators, Isotopes, Alpha particles, Block f elements, Plutonium, Melting point, Boiling point
What is Californium?
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Californium is a synthetic radioactive element.
- It is a member of the actinide group, one of the 15 radioactive metallic elements.
- The atomic number of californium is 98 and is found at the bottom row of the periodic table.
- It is available in block f of period 7.
- There are 20 isotopes of californium that have been identified and characterized with a mass number ranging from 237 to 256.
- These isotopes are also radioactive.
- Californium-257 is the most commonly used isotope of californium, particularly used in nuclear and industrial applications.
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| Related Concepts | ||
|---|---|---|
| Properties Of Matter | Properties Of Bases | Properties Of Colloids |
| Neoprene | Actinoids | Periodic Properties Of Elements |
Chemical Properties of Californium
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The following are the chemical properties of Californium
| Parameters | Value |
|---|---|
| Group | Actinides |
| Period | 7 |
| Atomic number | 98 |
| Block | f |
| Density (g cm−3) | 15.1 |
| Relative atomic mass | [251] |
| State at 20°C | Solid |
| Electron configuration | [Rn]5f10 7s2 |
| Key isotopes | 249Cf, 252Cf |
| Melting point | 900°C, 1652°F, 1173 K |
| CAS number | 7440-71-3 |
Uses of Californium
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Californium-252 is used for various purposes. Some of the uses of californium-252 are:
- It is used as a neutron source to initiate the nuclear fusion process in reactors.
- The neutrons released by californium can be used in the medical field to target certain cancer treatments.
- It can be used in various material scanning operations, like detecting gold and silver ores.
- It is used in neutron moisture gauges and devices to detect water and oil-bearing layers in oil wells.
- It is used to detect metal fatigue and stress in airplanes.
Properties of Californium
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The following are the Properties of Californium:
- Californium is a metal with a silvery-white appearance.
- It remains solid at room temperature at around 20oC.
- It is the heaviest actinide with a relative atomic mass of 251.
- It is malleable, i.e., it can be pressed or hammered into shape, without breaking.
- It is such a soft metal that it can be sliced with a razor blade.
- When californium is exposed to air, it tarnishes gradually.
- It is attacked by steam and acids readily.
- Californium (III) in an aqueous solution is the only stable ion that cannot be reduced or oxidized.
Health Effects of Californium
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If Californium is somehow consumed through food, drinks, and air, then 0.05% of californium reaches the bloodstream in one single instance.
- About 25% gets deposited in the liver, 65% in the skeleton, and the remaining in other organs or is excreted through urine.
- Californium can be hazardous for humans, and it has the following effects:
- It can disrupt the ability of the body to form red blood cells.
- It can cause external tissue damage through gamma-ray emission.
- Ionizing radiation emitted on bones and the liver can cause cancer.
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Things to Remember
- Californium is a radioactive metal that does not occur naturally.
- It belongs to the actinide group and is available in the periodic table at block f of period 7, with an atomic number of 98.
- Its appearance is silvery-white and is solid at room temperature. It is a soft metal that can be sliced is malleable.
- Its isotopes are used as a neutron emitter to start up nuclear reactors, to detect gold and silver ores, etc.
- The consumption of californium in any way can be hazardous to health.
Sample Questions
Ques. What is Californium? (2 Marks)
Ans. Californium is a synthetic chemical element with the symbol Cf and the atomic number 98. The element was originally synthesized in 1950 by bombarding curium with alpha particles at Lawrence Berkeley National Laboratory.
Ques. What is Californium used for? (2 Marks)
Ans. Californium is used in various areas like nuclear plants, medicine, oil and petrochemicals, material scanning, etc. Californium is used as a neutron source to start the nuclear reactor. They are used to treat certain cancer tumors. It can be used in various material scanning operations, like detecting gold and silver ores. It is used in neutron moisture gauges and devices to detect water and oil-bearing layers in oil wells.
Ques. Why is Californium so expensive? (2 Marks)
Ans. Californium is a very rare and radioactive element with a high cost of production. Its high cost is due to the difficult and costly procedure necessary to synthesize it, as well as its limited availability.
Ques. Where is Californium discovered? (2 Marks)
Ans. Californium was discovered in 1950 by bombarding curium with alpha particles (helium nuclei) at the University of California Radiation Laboratory in Berkeley.
Ques. What does Californium look like? (1 Mark)
Ans. Californium has a silver-white and metallic look with a melting point of around 900°C.
Ques. In what forms californium is available? (2 Marks)
Ans. There are two crystalline forms available under normal pressure (one above 900oC and one below). And there is a third form that is available under high pressure.
Ques. Which is the most stable isotope of californium? (1 Mark)
Ans. In the presence of oxygen, californium tarnishes. Californium (III) in an aqueous solution is the only stable ion that cannot be reduced or oxidized.
Ques. What are the properties of californium? (3 Marks)
Ans. The following are the properties of californium
- Californium is a silvery-white radioactive element.
- It is a soft metal that is malleable and so soft that it can be sliced by a razor blade.
- It is solid at room temperature but tarnishes as it comes in contact with air.
Ques. What is the location of californium in the periodic table? (2 Marks)
Ans. Californium has an atomic number 98 and that is why it is available at the bottom row of the period table. It is available among the group of actinides at block f of period 7.
Ques. What is the electronic configuration of californium? (1 Mark)
Ans. The electronic configuration of californium is [Rn] 5f10 7s2.
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