Chem 1010, week 5 notes: Isotopes and the periodic table
Chem 1010, week 5 notes: Isotopes and the periodic table CHEM 1010
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This 3 page Class Notes was uploaded by Chase Bobier on Monday February 22, 2016. The Class Notes belongs to CHEM 1010 at Middle Tennessee State University taught by Tammy J Melton in Fall 2015. Since its upload, it has received 42 views. For similar materials see Introductory General Chemistry I in Chemistry at Middle Tennessee State University.
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Date Created: 02/22/16
Chem 1010 Notes Chase Bobier Week 5 Notes. Important terms Things you need to know Atoms, Isotopes, and the Periodic Table of the Elements. Isotopes Isotopes are varieties of one element with a different number of neutrons in the nucleus. This change in atomic mass causes them to act in a slightly different manner than the original version of the element. Atoms have a neutral charge (The number of protons and electrons is even) Cations have a positive charge (The number of protons is greater than the number of electrons) Anions have a negative charge (The number of electrons outweighs the number of protons.) Atomic mass is the weight of a specific atom or isotope. It will always be a whole number. Atomic Weight is the average atomic mass of all known isotopes of an element, weighted in proportion of their natural abundances. How to perform a weighted average: (using Mg as the example) 1. Find atomic mass of all isotopes of given element. 2. Find the natural percentage of abundance of all of those isotopes. 3. Multiply each elements mass number by it’s % of abundance. 4. Average those numbers. Here’s an example: I want the atomic weight of Mg, I follow the fist step and find all of the isotopes of Mg, then I find the atomic masses of those isotopes and the % abundance of each. It looks like this (Table1) Symbol Mass # Isotope % Abundance Weight 24 25Mg 24 23.985 u 78.70% 12Mg 25 24.985 u 10.13% 26Mg 26 25.985 u 11.17% 12 (Table 1) Multiply each isotopes atomic weight by its % abundance. You get: 18.876195+2.5309805+2.9025245= 24.3097 24.3097 is your final answer. The Periodic Table of the Elements The Periodic table is chemistry’s road map, laid out in a way that you are able to derive a wealth of information about any given element from it and, if you’re particularly clever, elements that have yet to synthesized. The Periodic table is organized in order from least atomic number to highest atomic number. The entirety of the table is divided into four sections: Metals, Nonmetals, Transition Metals, and the Rare Earths. Metals are shiny, conductive of heat and electricity, , malleable, ductile, Solid art room temperature (with the exception of mercury), and they tend to lose electrons to form positive ions (also knows at cations.) Nonmetals are dull, are non-conductive, brittle, can be in any physical state at room temperature, and the tend to gain electrons to form negative ions (known as anions). Transition Metals are semiconductors and share characteristics with both metals and non-metals.