Does longer half-life mean more radioactive?

The longer the half-life of a nucleus, the lower the radioactive activity. A nucleus with a half-life that is a million times greater than another will be a million times less radioactive. A ‘half-life’ is defined as the amount of time taken for the number of nuclei present in a sample at a given time to exactly halve.

What does it mean if an element has a long half-life?

Half-life (symbol t1⁄2) is the time required for a quantity to reduce to half of its initial value. The term is commonly used in nuclear physics to describe how quickly unstable atoms undergo radioactive decay or how long stable atoms survive.

What is the longest radioactive half life?

Bismuth-209 (209Bi) is the isotope of bismuth with the longest known half-life of any radioisotope that undergoes α-decay (alpha decay). It has 83 protons and a magic number of 126 neutrons, and an atomic mass of 208.9803987 amu (atomic mass units).

Why is long half-life bad?

The biggest danger from radioisotopes with mid-to-long half lives is that they can keep an entire region of earth nastily radioactive for a very long time, e.g. hundreds or thousands or even tens of thousand of years.

Why do we measure half-life?

We use the half-life because radioactive decay is a matter of chance. When one atom will decay is anyone’s guess. If you have two identical atoms, one could decay immediately, the other could hang around for a century or a millenium.

How do scientists measure half-life?

We often talk about radioactive decay in terms of half-lives. A half-life is how much time it takes half of the radioactive atoms in a sample to decay. To measure the age of plant and animal remains from the more recent past, scientists use a radioactive isotope of carbon, called carbon-14, as their clock.

How do you determine long half-life?

The half-life is then determined from the fundamental definition of activity as the product of the radionuclide decay constant, λ, and the number of radioactive atoms present, N. One solves for λ and gets the half-life from the relationship λ = ln2/T1/2.

What is the half-life of carbon?

5,730 years
C has a half-life of 5,730 years. In other words, after 5,730 years, only half of the original amount of 14C remains in a sample of organic material.

What is a half-life of 30 years?

Hearing that cesium has a half-life of 30 years can be concerning. However, there are different types of half-lives that describe different things. The 30 years is the physical half-life….Half Lives.

Isotope	Physical Half-Life	Biological Half-Life
Sr-90	28 years	18,000 days