Inside the Atom The Nucleus 5.2

I.What’s in the nucleus? A.Atomic Number - the number of protons in the nucleus B.Isotopes a.Isotopes - atoms of the same element that have different numbers of neutrons b.Mass Number - number of neutrons plus protons in a nucleus c.Table Pg 136 C.Nuclear Glue a.Strong nuclear force holds the protons together only if they are nearly touching

II.Radioactive Decay A.Atomic nuclei are stable when they have about the same number of neutrons and protons B.In unstable atoms, the nucleus must release a particle a.Energy is given off b.Radioactive decay - the release of nuclear particles and energy c.Transmutation - one element changed into another through radioactive decay

C.Some Isotopes Release Alpha Particles a.Smoke Detectors i.Americium undergoes transmutation by emitting an alpha particle ii.Alpha Particle - two protons and two neutrons iii.Creates electric current iv.Smoke stops electric current and alarm is triggered b.After releasing the alpha particle Americium is now Neptunium

D.Some isotopes Release Beta Particles a.Beta particle - high energy electron from the nucleus b.Neutron split into proton and electron c.Beta Particle is released with a large amount of energy d.Because there is now an extra proton, the atomic number and element are changed e.The mass stays the same.

III.Half - Life A.Half-life - the amount of time required for half a sample of the element to decay B.Half-lives are different for each element C.Continues at a steady pace D.Carbon Dating a.Carbon-14 is used to date dead animals, plants, and humans b.Half-life of 5730 years c.Once dead the carbon stops replacing itself d.By comparing how much is left to how much a living organisms would have, the date can be determined

E.Nuclear Waste Products a.Nuclear waste products are isotopes that release large amounts of radiation b.Contained in special waste containers IV.New Elements by Transmutation A.Using a particle accelerator, scientists smash alpha and beta particles into existing elements B.The particles are absorbed and changes the existing element into a new element with a larger atomic number

C.These elements do not exist in nature D.Elements were created this way E.Tracer Elements a.Radioactive isotopes are introduced into a living organism b.The small half-lives prevent prolonged radiation c.Able to be followed by a device that detects radiation d.Used for medical diagnoses Pg