Semester One Notebook Etienne

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Learning Goal for this section: Explain and compare nuclear reactions (radioactive decay, fission and fusion), the energy changes associated with them and their associated safety issues. Notes Section: a nucleus has neutrons and protons outside has electron AMU= Atomic mass unit N- 1AMU neutral charge (+,-) P- 1AMU positive + E- none negative - ALPHA PARTICLES - 24 He 86 and beyond has at least one radioactive particle isotope is an element with different masses in atom some may be radioactive(radioactive isotope) carbon 14 - carbon molecule that dose not happen alot but everything has carbon the shroud of Turin shroud piece of cloth Turin city of Italy shroud of Turin cloth that wrapped Jesus body - not really carbon 14 because we know that carbon decays and we know the half life we can figure out how much time has passed- CARBON DATEING 90 238 U - 90 234 Th ALPHA RADIATION gives up a helium 24 He protons go down by 2 BETA PARTICLES- negative beta particle E-, positive beta particle E converts neutrons to protons carbon 14( 6 14 C) - 7 14 N stable go up by one can go through paper but not plastic or above in density boron( 58 B)- 48 Be a proton become a neutron go down by one GAMMA RADIATION- It is never alone associated with other type of nuclear decay you need led to protect your self it is just energy and is normally kept in led under ground and in limestone HALF LIFEcarbon 14---100 g start 20 mins 50g end- 50g start 40mins 25g- 25g start 60 mins 12.5g 54
The Nucleus A typical model of the atom is called the Bohr Model, in honor of Niels Bohr who proposed the structure in 1913. The Bohr atom consists of a central nucleus composed of neutrons and protons, which is surrounded by electrons which “orbit” around the nucleus. Protons carry a positive charge of one and have a mass of about 1 atomic mass unit or amu (1 amu =1.7x10- 27 kg, a very, very small number). Neutrons are electrically “neutral” and also have a mass of about 1 amu. In contrast electron carry a negative charge and have mass of only 0.00055 amu. The number of protons in a nucleus determines the element of the atom. For example, the number of protons in uranium is 92 and the number in neon is 10. The proton number is often referred to as Z. Atoms with different numbers of protons are called elements, and are arranged in the periodic table with increasing Z. Atoms in nature are electrically neutral so the number of electrons orbiting the nucleus equals the number of protons in the nucleus. Neutrons make up the remaining mass of the nucleus and provide a means to “glue” the protons in place. Without neutrons, the nucleus would split apart because the positive protons would repel each other. Elements can have nucleii with different numbers of neutrons in them. For example hydrogen, which normally only has one proton in the nucleus, can have a neutron added to its nucleus to from deuterium, ir have two neutrons added to create tritium, which is radioactive. Atoms of the same element which vary in neutron number are called isotopes. Some elements have many stable isotopes (tin has 10) while others have only one or two. We express isotopes with the nomenclature Neon-20 or 20 Ne 10, with twenty representing the total number of neutrons and protons in the atom, often referred to as A, and 10 representing the number of protons (Z). Alpha Particle Decay Alpha decay is a radioactive process in which a particle with two neutrons and two protons is ejected from the nucleus of a radioactive atom. The particle is identical to the nucleus of a helium atom. Alpha decay only occurs in very heavy elements such as uranium, thorium and radium. The nuclei of these atoms are very “neutron rich” (i.e. have a lot more neutrons in their nucleus than they do protons) which makes emission of the alpha particle possible. After an atom ejects an alpha particle, a new parent atom is formed which has two less neutrons and two less protons. Thus, when uranium-238 (which has a Z of 92) decays by alpha emission, thorium-234 is created (which has a Z of 90). Because alpha particles contain two protons, they have a positive charge of two. Further, alpha particles are very heavy and very energetic compared to other common types of radiation. These characteristics allow alpha particles to interact readily with materials they encounter, including air, causing many ionizations in a very short distance. Typical alpha particles will travel no more than a few centimeters in air and are stopped by a sheet of paper. 55
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Page 42: In the space below, write the unabb
Page 45 and 46: Research the Scientist and summariz
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Page 49 and 50: Define Ionization Energy: Ionizatio
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Page 69 and 70: Trigonal Planar Molecular Geometry
Page 71 and 72: Tetrahedral Molecular Geometry Orbi
Page 73 and 74: Bent Molecular Geometry Orbital Equ
Page 75 and 76: T-shaped Molecular Geometry Orbital
Page 77 and 78: Square Planar Molecular Geometry Or
Page 79 and 80: Name Formula Charge Dichromate Cr
Page 81 and 82: Chapter 23 Functional Groups The st
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Semester One Notebook Etienne

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