1st Semester Notebook

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54 Learning Goal for this section: The students will learn what happens when an unstable nucleus decays and how nuclear chemistry affects their lives. Notes Section: Neutrons are neutral because they are both positive and negative (+,-)=0 Isotopes are variant atoms with more/less neutrons, with different masses If an atom is equal in protons and neutrons, it is stable. Isotopes that are radioactive are unstable, as they're releasing neutrons. There is a certain amount of carbon when something is processed or created, and knowing the half-life, you can use that half-life to determine the age of something (carbon dating). Everything organic has a certain amount of carbon in it, making it possible to carbon date most previously living things. Helium (He) is the only alpha particle, and any radioactive decay leads to new products There is only one Helium per alpha radiation, and it results in two different products. Uranium 238(mass #) has 92 protons, and when it goes through alpha radiation, it would give out a Helium, which would give off two protons (#of Protons per Helium) and two neutrons, (the atomic mass of helium is 4, two neutrons & 2 protons) giving this equation: Ur238(92P)->*alpha radiation*->Thorium234(90P)+He4(2P) Alpha particle radiation on an element makes the element on the periodic table go down by 2 (Uranium down by 2=Thorium) Beta particles are electrons, and beta radiation is neutron (+,- =0) losing the negative charge inside, turning it into (+), becom proton. ex: C14(6P,8N)->*beta radiation*->N14(7P7N) Negative Beta radiation leads to an element going up by 1 in th eperiodic table. ex: C14(6P8N)->*beta raditation*->N14(7PN Positive Beta radiation takes a proton giving up a positive electron charge (e+), turning it into a neutron ex: B8 (Boron P5 N3)->*positive beta radiation*->Be (Berylium P4 N4) +e(+) Gamma Energy: Gamma radiation is just energy being released, associated with Alpha or Beta radiation (is like a byproduct) Half-life: given a radiaoctive substance, half life is the period of time it will take to lose half the mass it started with. 2 types of reactions: fission and fusion Fusion- Combining atoms into a larger atom Fission- Splitting of an atom (ex: shooting a neutron into Uranium 235,
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.
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Honors Chemistry Class Policies and
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Unit 1 (22 days) Chapter 1 Introduc
Page 6 and 7: Lorenzo Walker Technical High Schoo
Page 8: MUSTANG LABORATORIES COMMITMENT TO
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Page 14 and 15: 2. One cereal bar has a mass of 37
Page 16 and 17: 1. How many meters are in one kilom
Page 18 and 19: The Learning Goal for this assignme
Page 20 and 21: RULE #3: To add/subtract in scienti
Page 24 and 25: Rule 3: A final zero or trailing ze
Page 26 and 27: For addition and subtraction, look
Page 28 and 29: Dimensional Analysis This is a way
Page 30 and 31: Chapter 4 Unit 2 Atomic Structure T
Page 34 and 35: Looking at Ions We haven’t talked
Page 36 and 37: Neutron Madness We have already lea
Page 39 and 40: Electron Configuration Color the su
Page 41 and 42: Electron Configuration In order to
Page 43 and 44: Calcium [Ca] Nickel [Ni] Carbon [C]
Page 45 and 46: Research the Scientist and summariz
Page 47 and 48: Using Wikipedia, define the 8 categ
Page 49 and 50: Ionization Energy Define Ionization
Page 51 and 52: Ion Size Define Ion Size: Explanati
Page 53 and 54: 51 Chapter 7 Ionic and Metallic Bon
Page 55: 53 10. Name _______________________
Page 59 and 60: 57 Gamma Radiation After a decay re
Page 61 and 62: This analysis shows that sodium has
Page 63 and 64: 61 Metals, with only a few electron
Page 65 and 66: POLAR BONDING results when two diff
Page 67 and 68: Step 6 Put the atoms in the structu
Page 69 and 70: Trigonal Planar Molecular Geometry
Page 71 and 72: Tetrahedral Molecular Geometry Orbi
Page 73 and 74: 71 Bent Molecular Geometry Orbital
Page 75 and 76: 73 T-Shaped Molecular Geometry Orbi
Page 77 and 78: 75 Square Planar Molecular Geometry
Page 79 and 80: Name Formula Charge Dichromate Cr
Page 81 and 82: Chapter 23 Functional Groups The st
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1st Semester Notebook

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