Physio Chem 150 Week 4
Physio Chem 150 Week 4 Chem 150
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This 3 page Class Notes was uploaded by Brianna S. on Sunday September 18, 2016. The Class Notes belongs to Chem 150 at Xavier University taught by Dr. Stroud in Fall 2016. Since its upload, it has received 13 views. For similar materials see Physiological Chemistry in Chemistry at Xavier University.
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Date Created: 09/18/16
Physiological Chemistry 150 Lecture Notes Week Four: 9/12-9/16 Atoms and Elements Chemical Equations Chemical reactions are conveyed via a chemical reaction o Reactants Products Chemical equations show the energy released or absorbed Balanced equations are used to obey the Law of Conservation of Matter o Atoms are equal in the beginning as in the end Example: Magnesium and oxygen combine to make magnesium oxide, MgO. Balance the equation, remember “” means “yields” or “equals” 2 Mg + O 2 2 MgO *The number of reactant atoms must be equal to the number of product atoms Thermochemical equation shows the chemical reaction with all symbols for elements and formulas for compounds correctly indicated: o Must be balanced, using correct coefficients o Must properly show states of matter (i.e. s, l, g, and aq) (aq) -> aqueous meaning dissolved in water Example: 2Mg (s) 0 2 (g)2MgO (s) light Exothermic reactions: release heat (evolved energy) Endothermic reactions: absorb heat (energy needed) o All most all chemical changes or reactions involve changes in energy o Energy may be Needed in the form of heat, electricity or light o Energy may be Evolved in the form of sound, heat or light Atom Smallest part of the element that possess the properties of the element Modern Atomic Theory: 1. All matter is composed of atoms. Elements are composed of tiny particles called atoms. 2. With the exception of mass, atoms of the same element are identical; atoms of different elements have different masses and different properties 3. Chemical compounds consist of atoms arranged in specific ratios a. Example: H 02(water) 2 Hydrogen : 1 Oxygen b. Example: H 02(H2drogen peroxide) 2 Hydrogen : 2 Oxygen 4. Chemical reactions involve the union, separation and/or rearrangements of atoms. The atoms themselves are unchanged by the chemical reaction a. In nuclear reactions, the atoms are changed Definitions: Neutron- can be found in the nucleus of an atom, has a neutral (0) charge and has a mass of 1 x 10 -24 Proton- can be found in the nucleus of an atom, has a positive -24 (+1) charge and has a mass of 1 x 10 Electron- can be found outside the nucleus of an atom, has a negative (-1) charge and has a mass of 1 x 10 -28 - Atomic Number can be used to identify the elements because they are the unique number of protons in each element - A neutral atom has an equal number of protons and electrons; therefore the atomic number shows how many protons and electrons the element has Isotopes - Different form of an element (difference in neutrons) - Exist for most elements Example: Carbon – 12 (mass number) has 6 protons, 6 neutrons and 6 electrons Carbon – 14 has 6 protons, 8 neutrons and 6 electrons * Both are Carbon elements with a different number of neutrons showing they are isotopes of Carbon Remember: Hydrogen Isotopes have diff names… H–1 is Protium, H–2 is Deuterium and H–3 is Tritium Atomic Mass Is the weighted average mass The relative abundance of each isotope To calculate Atomic Mass Use an experimental percent abundance of each isotope of the element Multiply the percent abundance by the atomic mass of that isotope Sum the total mass of each isotope For example: Find the atomic mass of Gallium–69 and Gallium–71, if Ga–69 has a 60.10% and the atomic mass is 68.926 amu, while Ga–71 has a 39.90% and the atomic mass is 70.925 amu. Gallium–69 .6010 x 68.926 = 41.42 amu Gallium–71 .3990 x 70.925 = 28.30 amu 41.42 + 28.30 = 69.72 amu *the atomic mass of Gallium*
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