Chapter 25 – Nuclear Changes 25.1 - Radioactivity.
Post on 28-Dec-2015
Chapter 25 Nuclear Changes25.1 - Radioactivity
ObjectivesDescribe the structure of an atom and its nucleus.Explain what radioactivity is.Compare and contrast properties of radioactive and stable nuclei.Discuss the discovery of radioactivity.
NucleusComposed of protons and neutrons which account for most of the atoms mass
Strong forceCauses protons and neutrons to be attracted to each other in the nucleus
Video clipThe strong force is powerful only when neutrons and protons are close to each otherThe protons and neutrons in a large nucleus are held less tightly by the strong force than those in a small nucleus
RadioactivityThe nuclear decay that occurs when the strong force is not large enough to hold the nucleus together and the nucleus gives off matter and energy
IsotopesAtoms of the same element with varying number of neutrons
A nucleus with too many or too few neutrons compared to protons is radioactiveAtomic number = number of protons in an atomMass number = number of protons and neutrons in a nucleusIf an element has a neutron to proton ratio of 1.2 or higher than the element is radioactive
SymbolAtomic NumberNumber of protonsMass NumberNumber of Neutrons1H11110235U929292235235-92 = 143
Element RadioactivityUranium was discovered in 1896 by Henri Becquerel as a radioactive element
Polonium and Radium were discovered as radioactivity by Marie and Pierre Curie in 1898Video Clip
In-Class Assignment/Homework25.1 Reinforcement WKTTomorrow 25.1 Enrichment WKT25.1 & 25.2 Directed Reading WKT