Thursday, September 24, 2009

Chemical formulas

Today students reviewed Lewis dot structures and how to find charges. Everyone has a good handle on this and did well on their little quiz.

Students learned how to decode the charges of the metals in the middle. Transition metals, inner transition metals, and metals under the stairs do not follow any sort of pattern when it comes to charges, so they are always given (or you can figure them out) based on a code of Roman Numerals.

Today we also discussed how to write chemical formulas, and what the numbers associated with a chemical formula mean. Coefficients are the big numbers in front and are distributed to the whole molecule (which means you may have to multiply). Subscripts are the little lower numbers and they indicate the number of atoms and only apply to the atom it is to the right of. Students wrote their name as a chemical compound and thought it looked pretty interesting. Some students have long formulas, other short. Even twins do not have the same chemical formula.

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