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Showing posts from May 4, 2009

Element List

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Atomic Number, Element Symbol & Element Name Here's a list of chemical elements ordered by increasing atomic number. The names and element symbols are provided. 1 - H - Hydrogen 2 - He - Helium 3 - Li - Lithium 4 - Be - Beryllium 5 - B - Boron 6 - C - Carbon 7 - N - Nitrogen 8 - O - Oxygen 9 - F - Fluorine 10 - Ne - Neon 11 - Na - Sodium 12 - Mg - Magnesium 13 - Al - Aluminum, Aluminium 14 - Si - Silicon 15 - P - Phosphorus 16 - S - Sulfur 17 - Cl - Chlorine 18 - Ar - Argon 19 - K - Potassium 20 - Ca - Calcium 21 - Sc - Scandium 22 - Ti - Titanium 23 - V - Vanadium 24 - Cr - Chromium 25 - Mn - Manganese 26 - Fe - Iron 27 - Co - Cobalt 28 - Ni - Nickel 29 - Cu - Copper 30 - Zn - Zinc 31 - Ga - Gallium 32 - Ge - Germanium 33 - As - Arsenic 34 - Se - Selenium 35 - Br - Bromine 36 - Kr - Krypton 37 - Rb - Rubidium 38 - Sr - Strontium 39 - Y - Yttrium 40 - Zr - Zirconium 41 - Nb - Niobium 42 - Mo - Molybdenum 43 - Tc - Technetium 44 - Ru - Ruthenium 45 - Rh - Rhodium 46 - Pd - Palla...

Periodic Table of the Elements

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Click on an element symbol in the periodic table to get facts for that element. Printable periodic tables and a list of elements by increasing atomic number are also availab

What Is a Mole and Why Are Moles Used

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Question: What Is a Mole and Why Are Moles Used? Answer: A mole is simply a unit of measurement. Units are invented when existing units are inadequate. Chemical reactions often take place at levels where using grams wouldn't make sense, yet using absolute numbers of atoms/molecules/ions would be confusing, too. Like all units, a mole has to be based on something reproducible. A mole is the quantity of anything that has the same number of particles found in 12.000 grams of carbon-12. That number of particles is Avogadro's Number, which is roughly 6.02x1023. A mole of carbon atoms is 6.02x1023 carbon atoms. A mole of chemistry teachers is 6.02x1023 chemistry teachers. It's a lot easier to write the word 'mole' than to write '6.02x1023' anytime you want to refer to a large number of things! Basically, that's why this particular unit was invented. Why don't we simply stick with units like grams (and nanograms and kilograms, etc.)? The answer is that mole...

Molecular Weight and Formula Weight

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The molecular weight of a molecule is calculated by adding the atomic weights (in atomic mass units or amu) of the atoms in the molecule. The formula weight of an ionic compound is calculated by adding its atomic weights according to its empirical formula. *The Mole A mole is defined as the quantity of a substance that has the same number of particles as are found in 12.000 grams of carbon-12. This number, Avogadro's number, is 6.022x1023. The mass in grams of one mole of a compound is equal to the molecular weight of the compound in atomic mass units. One mole of a compound contains 6.022x1023 molecules of the compound. The mass of 1 mole of a compound is called its molar weight or molar mass. The units for molar weight or molar mass are grams per mole. Here is the formula for determining the number of moles of a sample: mol = weight of sample (g) / molar weight (g/mol)

Molecules and Moles

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@@@ Learn about Molecules. Moles and Avogadro's Number @@@ Molecules and Moles A molecule is a combination of two or more atoms that are held together by covalent bonds. A molecule is the smallest unit of a compound that still displays the properties associated with that compound. Molecules may contain two atoms of the same element, such as O2 and H2, or they may consist of two or more different atoms, such as CCl4 and H2O. In the study of chemistry, molecules are usually discussed in terms of their molecular weights and moles. Ionic compounds, such as NaCl and KBr, do not form true molecules. In their solid state, these substances form a three-dimensional array of charged particles. In such a case, molecular weight has no meaning, so the term formula weight is used instead.