1 : the time required for half of something to undergo a process: as a : the time required for half of the atoms of a radioactive substance to become disintegrated b : the time required for half the amount of a substance (as a drug or radioactive tracer) in or introduced into a living system or ecosystem to be eliminated or disintegrated by natural processes
2 : a period of usefulness or popularity preceding decline or obsolescence <slang usually has a short half-life>
2 : a period of usefulness or popularity preceding decline or obsolescence <slang usually has a short half-life>
For americium-241, it is known that half of the atoms decay in 458 years. Therefore, 458 years is the half-life of americium-241. Every radioactive element has a different half-life, ranging from fractions of a second to millions of years, depending on the specific isotope. For example, americium-243 has a half-life of 7,370 years.
by Mark January 06, 2004
by Mark March 21, 2005
by Mark September 04, 2004
by Mark September 02, 2004
a name of a girl with usually a middle eastern descent.
it means a gift from god.
girls with this name have the ability to be creative along practical lines of endeavour. their ideas can be very original and inventive. they enjoy being with people in a social environment. to them their personal appearance is important, and also the desire to make a good impression on others. their pleasant manner attracts people to them with their problems and those girls are capable of offering practical advice. these girls, however, are somewhat too concerned with the personalities, problems, and activities of other people.
it means a gift from god.
girls with this name have the ability to be creative along practical lines of endeavour. their ideas can be very original and inventive. they enjoy being with people in a social environment. to them their personal appearance is important, and also the desire to make a good impression on others. their pleasant manner attracts people to them with their problems and those girls are capable of offering practical advice. these girls, however, are somewhat too concerned with the personalities, problems, and activities of other people.
hiba is a nice girl.
by mark March 01, 2005
by Mark October 25, 2003
by Mark July 14, 2008