2007-01-26 05:24:47 · 8 answers · asked by Anonymous in Science & Mathematics ➔ Astronomy & Space
Hydrogen is by far the most common element in the universe, followed by Helium. The least common elements in the Universe are going to be the ones with really high decay rates...
If you are talking the least common moderately stable elements, It's still going to be your real heavy and radioactive elements. One page I found said that Uranium has the lowest abundance in the solar system, with Thorium being second least abundant.
Hope that helps. Try reading these links:
2007-01-26 05:30:01 · answer #1 · answered by ~XenoFluX 3 · 3⤊ 0⤋
Simple, the most common elements are Hydrogen, Helium, Carbon, Nitrogen, and Oxygen. The common elements are the ones you hear about all the time, the uncommon ones are the ones you don't.
2007-01-26 08:25:20 · answer #2 · answered by Tom 2 · 0⤊ 2⤋
Hydrogen is the most common by far. I think Technetium is the least common of the "natural" elements on Earth. I think applying that to the Universe is conjecture.
2007-01-26 05:33:46 · answer #3 · answered by gebobs 6 · 2⤊ 0⤋
Astatine is the rarest on earth.
Astatine is a chemical element in the periodic table that has the symbol At and atomic number 85. This radioactive element occurs naturally from uranium-235 and uranium-238 decay; it is the heaviest of the halogens.
Notable characteristics
This highly radioactive element has been confirmed by mass spectrometers to behave chemically much like other halogens, especially iodine (it would probably accumulate in the thyroid gland like iodine). Astatine is thought to be more metallic than iodine. Researchers at the Brookhaven National Laboratory have performed experiments that have identified and measured elementary reactions that involve astatine; however, chemical research into astatine is limited by its extreme rarity, which is a result of its extremely short half-life.
Astatine is the rarest naturally-occurring element, with the total amount in Earth's crust estimated to be less than 1 oz (28 g) at any given time; this amounts to less than one teaspoon of the element. The Guinness Book of Records has dubbed the element the rarest on Earth, stating: "Only around 0.9 oz (25 g) of the element astatine (At) occurring naturally"; Isaac Asimov wrote a 1955 essay on large numbers, scientific notation, and the size of the atom, in which he stated that the number of astatine atoms on Earth at any time was "only a trillion".
ALMOST AS RARE ARE the five other very rare, highly radioactive cis-Uranic elements (polonium, francium, radium, actinium and protactinium), as their natural abundances are too low to have been accurately measured.
THE MOST COMMON ELEMENTS IN THE UNIVERSE
These are the ten most common elements in the Universe as measured in parts per million:
Element Parts per million
Hydrogen 739,000
Helium 240,000
Oxygen 10,700
Carbon 4,600
Neon 1,340
Iron 1,090
Nitrogen 970
Silicon 650
Magnesium 580
Sulfur 440
2007-01-26 15:01:59 · answer #4 · answered by Anonymous · 2⤊ 0⤋
The two most common elements in the universe are Hydrogen and stupidity.
by Harlan Ellison
2007-01-26 06:14:29 · answer #5 · answered by ? 6 · 0⤊ 0⤋
Hydrogen is the most common. Probably helium is second.
The least common would be whichever artificial transuranic element has the shortest half-life.
2007-01-26 05:41:57 · answer #6 · answered by Anonymous · 0⤊ 0⤋
The most common is hydrogen
The least common is unknown. It appears so rarely that no one has been able to find out what it is!
2007-01-26 08:18:19 · answer #7 · answered by Always Hopeful 6 · 0⤊ 0⤋
Carbon is the most common. Some metals like titanium and plutonium are very uncommon. I am sure there are many others but Carbon is the most common.
2007-01-26 05:31:42 · answer #8 · answered by stricklins 3 · 0⤊ 6⤋