The heaviest nucleus considered to be stable is now lead-208 and the heaviest stable monoisotopic element is gold as the 197Au isotope.
Detailed Solution. Lead or Pb-208 is the heaviest stable isotope. The elements without any stable isotopes are technetium (atomic number 43), promethium (atomic number 61), and all observed elements with atomic numbers greater than 82.
Lead-208 has 126 neutrons, another magic number, which may explain why lead-208 is extraordinarily stable. With its high atomic number, lead is the heaviest element whose natural isotopes are regarded as stable; lead-208 is the heaviest stable nucleus.
Nevertheless, the successful synthesis of superheavy elements up to Z = 118 (oganesson) with up to 177 neutrons demonstrates a slight stabilizing effect around elements 110 to 114 that may continue in unknown isotopes, consistent with the existence of the island of stability.
Now coming to your question there is an exception helium-3 is the only stable isotope of any element with more protons than neutrons .
Complete answer: Iron is the most stable element in terms of structural stability and in terms of nuclear stability but not in terms of the chemical stability.
Lead's four stable isotopes each have 82 protons, a magic number in the nuclear shell model of atomic nuclei. The isotope lead-208 also has 126 neutrons, another magic number, and is hence double magic, a property that grants it enhanced stability: lead-208 is the heaviest known stable nuclide.
Unbinilium, also known as eka-radium or element 120, is the hypothetical chemical element in the periodic table with symbol Ubn and atomic number 120.
The rarest stable metal is tantalum. The rarest metal on earth is actually francium, but because this unstable element has a half life of a mere 22 minutes, it has no practical use.
Oganesson, named for Russian physicist Yuri Oganessian (SN: 1/21/17, p. 16), is the heaviest element currently on the periodic table, weighing in with a huge atomic mass of about 300. Only a few atoms of the synthetic element have ever been created, each of which survived for less than a millisecond.
Uranium was discovered in 1789 by German chemist Martin Heinrich Klaproth. It is the heaviest naturally occurring element in the universe and is naturally radioactive.
The heaviest element discovered is Ununoctium or Organesson with atomic number 118 but it is man-made. The heaviest naturally occurring element is Uranium with atomic number 92 and atomic weight 238 gm.
The Heaviest Metal. The heaviest metal is osmium, which has, bulk for bulk, nearly twice the weight of lead.
Osmium is the densest element on the periodic table. It has a density of 22.6 grams per cubic centimetre. Tungsten is the second densest element on the periodic table. It has a density of 19.3 grams per cubic centimetre.
Hydrogen is the first element on the periodic table and its atomic number is 1 which means there is only 1 electron in its outermost shell. So, it is placed in group 1 with alkali metals and in period 1and its electronic configuration is $1{{s}^{1}}$. This is a very unstable configuration.
The elements osmium, iridium, rhenium, neptunium and plutonium are also heavier than gold.
As the rarest of the platinum group metals, rhodium occurs at roughly 0.000037 parts per million in the Earth's crust, while gold is found at an abundance of around 0.0013 parts per million, according to the Royal Society of Chemistry.
As the ninth-most abundant element in the Earth's crust, titanium is relatively rare. Research shows the strong and lightweight metal only accounts for roughly 0.63% of the Earth's crust. With such little titanium available, it costs more to harvest and produce than other metals.
Because electrons have non zero rest mass, they cannot exceed the vacuum speed of light according to Einstein's theory of relativity. Thus, atoms with Z > 137 cannot exist. Legend has it that the great physicist, Richard Feynman, first argued that element 137 was the largest possible element2.
Ununennium, also known as eka-francium or element 119, is the hypothetical chemical element with symbol Uue and atomic number 119. Ununennium and Uue are the temporary systematic IUPAC name and symbol respectively, which are used until the element is discovered, confirmed, and a permanent name is decided upon.
The first elements — hydrogen and helium — couldn't form until the universe had cooled enough to allow their nuclei to capture electrons (right), about 380,000 years after the Big Bang.
Francium is a chemical element with the symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called actinium K after the natural decay chain in which it appears), has a half-life of only 22 minutes.
Stable isotopes do not decay into other elements. In contrast, radioactive isotopes (e.g., 14C) are unstable and will decay into other elements.
Bismuth was long considered the element with the highest atomic mass whose nuclei do not spontaneously decay. However, in 2003 it was discovered to be weakly radioactive.