CHEM 121 CHAPTER 2 OUTLINE
CHEM 121 CHAPTER 2 OUTLINE 20322
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This 2 page Class Notes was uploaded by Amanda Bates on Monday January 11, 2016. The Class Notes belongs to 20322 at Eastern Michigan University taught by Vicki paulissen in Fall 2015. Since its upload, it has received 17 views. For similar materials see Chem 121 in Chemistry at Eastern Michigan University.
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Date Created: 01/11/16
CHAPTER TWO OUTLINE 2.1: The nuclear model of atomic structure Atoms are made up of smaller particles called subatomic particles. Cathode Rays are invisible to the naked eye, but when the end of the CRT (cathoderay tube) opposite to the cathode is coated with a phosphorescent material, a glowing spot appears where the beam hits. Thomson found that cathoderay beams are deflected by magnetic fields and electric fields. The observation established that the particles in the cathode rays, which are now known as electrons, are fundamental particles present in all forms of matter. Knowing Thomson’s va23 of m/e for the electron, Millikan calculated the mass of the electron: 9.10 x 10 g. Radioactivity and the Nuclear Atom Rutherford found that beta particles penetrate materials better than alpha particles. Alpha particles are positively charged; Beta particles are negatively charged. In the gold foil experiment, most alpha particles passed directly through the gold foil, however, about 1 in every 8000 particles was deflected from the foil through an average of angle of 90 degrees. Protons and Neutrons One amu is 1/12 the mass of a carbon atom. Neutron mass is 1.00867 with NO CHARGE. Protons mass is 1.00728 with a POSTIVE CHARGE. 4 Electrons mass is 5.485799 x 10 NEGATIVE CHARGE. 2.2: Isotopes Aston discovered that neon had several different amus. He proposed that neon had isotopes. Isotopes have the same number of protons, but different number of neutrons. The number of protons is called the atomic number. The number of nucleons in the nucleus is the mass number. An ion is an atom or group of atoms that has a net positive or negative charge. 2.3: Average Atomic Mass The number above the symbol is the element’s atomic number and the number below the symbol is the element’s average atomic mass. Natural abundance is usually expressed in percentage. To determine the average atomic mass, we multiply the mass of each isotope by its natural abundance Turn the natural abundance into decimals when calculating the average atomic mass. 2.4: The Periodic Table of Elements There are 18 groups in the periodic table. Elements in the same group have similar properties. Halogens are group 17 of the periodic table. Alkali metals are group 1 of the periodic table. Alkaline earth metals are group 2 of the periodic table. Metals are on the left side of the periodic table and are shiny solids that conduct heat and electricity well and are malleable and ductile. Nonmetals have poor heat conductivity and electricity. Metalloids are elements along the border between metals and nonmetals in the periodic table; they have some metallic and nonmetallic properties. The main group elements are group 1,2, and 1318 on the periodic table. The transition metals are in groups 312 of the periodic table. Nobel gases are group 18 on the periodic table. 2.5: Trends in Compound Formation Molecular Compounds A molecular compound is made up of 2 metals, held together by a covalent bond. Ionic Compound Contain a metal element. Cations are positively charged. Anions are negatively charged. The empirical formula is a formula showing the smallest whole number ratio of elements in a compound. Group 1 has a 1+ charge. Group 2 has a 2+ charge. Elements in the same group have the same charge. 2.6: Naming Compounds and Writing Formulas Binary Molecular Compounds Write down the name of the first element in the formula. Change the ending of the name of the second element to “ide”. Add prefixes to the first and second names to indicate the number of atoms of each type of molecule. Binary Ionic Compounds Start with the name of the cation, which is simply the name of the parent element. Add the name of the anion, which is the name of the element except that the ending is changed to “ide”. Binary Compounds of Transition Metals We use the roman numeral after the transition metals to indicate the charge of the element. Polyatomic Ions Polyatomic ions that contain oxygen and one or more elements are called oxcanions. Refer back to table 2.3 on page 60. Refer back to table 2.4 on page 61. Acids Affix the prefix hydro to the name of the element other than hydrogen. Replace the last syllabus in the element name with the suffix –ic, and add acid.
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