The same element with a different number of neutrons: EX- C-12(6n°), C-13(7n°) & C-14 (8n°) = the Real Mass: An average of all the isotopes of that element.
The nucleus of an atom breaks down and emits radioactive particles: EX- Alpha- slow, absorbed by a substance thicker than paper Beta- almost the speed of light-more penetration: can go through thin copper sheet Gamma- travels at the speed of light and can penetrate lead. 299,792,458 m/s!! Uses in Industry: Check the thickness of paper and plastic, keep food fresh, radioactive tracing (track substances through the body) and radiotherapy (kills cancer cells)
The amount of time it takes for half of the atoms in a radioactive sample to decay. EX- C14= 5,700 yrs. & Be11= 13.81s The half-life for a given isotope is always the same. It doesn’t depend on how many atoms you have or how long they have been sitting around! EX- Be11(changes to B11) 16g---- 8g 4g ---- 2g 13.81s 13.81s 13.81s 3-Half-lives have passed!!