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Unit 4-Atoms

Covers topics from History of Atom to Nuclear Reactions and Equations

QuestionAnswer
In 460 B.C., who developed the idea of the atom? Democritus
What did John Dalton do in 1766-1844? Created the atomic theory and stated that the atom is one, solid sphere.
What did J.J. Thomson's Cathode Ray Experiment show? Electrons are embedded in a ball of positive charge. They are not indivisible, but are composed of smaller particles called subatomic particles.
Who used the Gold Foil Experiment to reveal the true atom arrangement-atom is nearly all empty space? Ernest Rutherford
What are isotopes? Atoms of the same element that differ in mass due to difference in number of neutrons.
What does the mass number (A) do? Defines a particular isotope Determines total number of protons and neutrons
What is an ion? An atom with a charge
How are ion's formed? By changing the number of electrons. It is still the same element, only charged.
What is Cation? Losing an electron. Positive ion.
What is Anion? Gaining an electron. Negative ion.
What is the Average Atomic Mass? The weighted average mass of an element's isotope. Depends on percent abundance of each isotope.
How do you calculate Average Atomic Mass? 1. Convert all percents to decimal form 2. Multiply each mass by its percent abundance 3. Add together for average atomic mass
How do you find relative abundances? Work backwards to determine the relative abundance of isotopes.
What is radiation? Spontaneous emission of particles from the nuclei of unstable radioisotopes
Marie Curie coined what term? Radioactive
When are radioisotopes more stable? When they have high nuclear binding energy, when they have even numbers of protons and neutrons, and when they are along the Ideal N/Z ratio (neutron/proton)band.
What is radioactive nuclear decay? Unstable radioisotopes the spontaneously break down. These emit particles (radiation) and form more stable isotopes.
What is transmutation? When the number of proton's in the nucleus must change.
What is Alpha Decay? Release of alpha particles. 4He 2
What is Beta Minus Decay? High energy electrons where the neutrons are changed to protons. 0e -1
What is Positron Emission? Emission of positron (anti electron) where the protons are converted to neutrons. 0e +1
What is Electron Capture? When the nucleus captures an electron. 0e -1
What is Gamma Emission? Occurs with "nuclear rearrangement" (high to low energy state). Pure energy that can occur with other types of decay. 0Y 0
What is mass defect? The mass lost when forming/rearranging nuclei
What is nuclear binding energy? The energy produced when forming/rearranging nuclei.
What is E=mc^2 A mass energy equivalence equation used to find energy emitted when forming/rearranging nuclei.
What is Fusion? When the lighter nuclei join together.
What is Fission? When the heavier nuclei split and break apart. Enormous energy release causes chain reaction. Neutrons released in the fission of one atom trigger fission in another nearby atom.
What is Half-Life? The time it takes for half of a sample of radioactive isotopes to decay.
Half-Life Equation N=No(1/2)^t/t1/2
Created by: HopeSpangler
 

 



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