What are the most common isotopes of helium?
Helium-4 is by far the most plentiful of the stable isotopes: helium-4 atoms outnumber those of helium-3 about 700,000:1 in atmospheric helium and about 7,000,000:1 in certain helium-bearing minerals.
How many isotopes of helium are there?
Although there are eight known isotopes of helium (He) (standard atomic mass: 4.002602(2) u), only helium-3 (3He) and helium-4 (4He) are stable. All radioisotopes are short-lived, the longest-lived being 6He with a half-life of 806.7 milliseconds.
Is samarium an isotope?
Naturally occurring samarium (62Sm) is composed of five stable isotopes, 144Sm, 149Sm, 150Sm, 152Sm and 154Sm, and two extremely long-lived radioisotopes, 147Sm (half life: 1.06×1011 y) and 148Sm (7×1015 y), with 152Sm being the most abundant (26.75% natural abundance).
What are the 6 isotopes of helium?
Element “Helium” has two stable isotopes (3He and 4He) and six radioactive ones (5He, 6He, 7He, 8He, 9He, and 10He).
Does helium have any isotopes?
The known isotopes of helium contain from one to six neutrons, so their mass numbers range from three to eight. Of these six isotopes, only those with mass numbers of three (helium-3, or 3He) and four (helium-4, or 4He) are stable; all the others are radioactive, decaying very rapidly into other substances.
Where is samarium commonly found?
Samarium is the fifth most abundant of the rare elements and is almost four times as common as tin. It is never found free in nature, but in contained in many minerals, including monazite, bastnasite and samarskite. Samarium containing ores are found in USA, China, Brazil, India, Australia and Sri Lanka.
What is samarium made of?
Samarium is used to dope calcium chloride crystals for use in optical lasers. It is also used in infrared absorbing glass and as a neutron absorber in nuclear reactors. Samarium oxide finds specialised use in glass and ceramics….
| Discovery date | 1879 |
|---|---|
| Discovered by | Paul-Émile Lecoq de Boisbaudran |
What are the 3 isotopes of helium?
Element “Helium” has two stable isotopes (3He and 4He) and six radioactive ones (5He, 6He, 7He, 8He, 9He, and 10He). Half lives of the latter ones are significantly short, up to only 0.8 sec. They are not naturally occurring and do not contribute geochemistry and cosmochemistry.
Why is helium-4 an isotope?
Its nucleus is identical to an alpha particle, and consists of two protons and two neutrons. Alpha decay of heavy elements in the Earth’s crust is the source of most naturally occurring helium-4 on Earth, produced after the planet cooled and solidified….Helium-4.
| General | |
|---|---|
| Symbol | 4He |
| Names | helium-4, He-4 |
| Protons | 2 |
| Neutrons | 2 |
What is samarium most commonly used for?
Samarium is used to dope calcium chloride crystals for use in optical lasers. It is also used in infrared absorbing glass and as a neutron absorber in nuclear reactors. Samarium oxide finds specialised use in glass and ceramics.
Is samarium rare or common?
Although classified as a rare-earth element, samarium is the 40th most abundant element in the Earth’s crust and is more common than metals such as tin.
How many isotopes of samarium are there?
Naturally occurring samarium ( 62 Sm) is composed of five stable isotopes, 144 Sm, 149 Sm, 150 Sm, 152 Sm and 154 Sm, and two extremely long-lived radioisotopes, 147 Sm (half life: 1.06 × 10 11 y) and 148 Sm (7 × 10 15 y), with 152 Sm being the most abundant (26.75% natural abundance ).
How many radioisotopes of helium are there?
Isotopes of helium Although there are eight known isotopes of helium (He) (standard atomic mass: 4.002602(2) u), only helium-3 (3He) and helium-4 (4He) are stable. All radioisotopes are short-lived, the longest-lived being 6He with a half-life of 806.7 milliseconds.
What is the half-life of samarium?
Samarium also has five nuclear isomers with the most stable being 141m Sm ( half-life 22.6 minutes), 143m1 Sm ( t1/2 = 66 seconds) and 139m Sm ( t1/2 = 10.7 seconds).
Which isotopes of samarium decay by beta decay?
The long lived isotopes, 146 Sm, 147 Sm, and 148 Sm, primarily decay by alpha decay to isotopes of neodymium. Lighter unstable isotopes of samarium primarily decay by electron capture to isotopes of promethium, while heavier ones decay by beta decay to isotopes of europium.