The radioactive elements are unstable due to extra excitement in their nucleus.
The nucleons i.e. the protons and the neutrons are affected by various interactions inside the nucleus like the strong nuclear force and the electrostatic forces and other factors as well.
All these factors result in a high excited stage.
Hence, the high excitement nucleus tries to get a state of low energy or excitement.
Thus, the radioactive nuclei decay by either Alpha decay or Beta decay and further go to low energy state by radiating energy in the form of Gamma radiations.
Unstable chemical elements are disintegrated by radioactive decay.
Radioactive
All elements have unstable isotopes so the answer would be everywhere. However if you mean 'elements with only unstable isotopes' thennumber 43 Technetiumnumber 61 Promethiumeverything above 92
It isn't really an ELEMENT that is unstable, but an ISOTOPE. That means that in general, for the same element, some atoms will decay, and some will not - the difference being the number of neutrons in the nucleus.
Iron (Fe) and sulfur (S) are not considered unstable atoms. Both elements are stable on their own in their natural state. However, certain isotopes of iron and sulfur can be unstable and undergo radioactive decay.
Unstable chemical elements are disintegrated by radioactive decay.
Radioactive elements are unstable, and the shorter the half-life, the more unstable they are.
Unstable elements that decay or break down into different elements are called radioactive elements. These elements have an unstable atomic nucleus that undergoes radioactive decay, transforming into a different element and releasing energy in the process. Examples of radioactive elements include uranium, radium, and plutonium.
Radioactive
Transuranium elements are radioactive and unstable; the stability of a nucleus is a problem of nucleon physics.
All elements have unstable isotopes so the answer would be everywhere. However if you mean 'elements with only unstable isotopes' thennumber 43 Technetiumnumber 61 Promethiumeverything above 92
All are radioactive, dangerous and unstable
The elements described are said to be radioactive.
Radioactive elements, such as uranium and thorium, are unstable and undergo radioactive decay to form other elements. This process involves the emission of particles or energy from the nucleus of the unstable element to achieve a more stable configuration.
This phenomenon is called radioactive disintegration.
If you mean oxygen: like most elements, it has both stable isotopes, and unstable (i.e., radioactive) isotopes. 16O, 17O and 18O are stable; the unstable (radioactive) isotopes include 15O and 14O.
It isn't really an ELEMENT that is unstable, but an ISOTOPE. That means that in general, for the same element, some atoms will decay, and some will not - the difference being the number of neutrons in the nucleus.