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Iunit 11 chemisrty1/4/2024 ![]() (1 u) Roughly the mass of one _ or one _ 1 u = x kg Defined as 1/12 mass of carbon-12 _ The Periodic Table lists the atomic masses of each element in _ Since we deal with more than one atom at a time, we need a way to go from the macroscopic scale to the atomic scale and vice-versa… proton neutron atom a.m.u.Ģ9 The Mole The Mole – one mole of carbon-12 has a mass of 12 grams and contains 6.02 x 1023 atoms of carbon A mole is a number of something, like a dozen means _ of something or a gross is _ of something – Could you have a mole of cars? _ 6.02 x 1023 is known as Avogadro’s number and is the number of things in a mole of that thing One mole of cars would be _ cars A mole of carbon-12 atoms is defined as having a mass of _ 12 144 Yes! 6.02 x 1023 12 gramsģ0 Molar weights _ atomic weight - mass in _ equal to atomic weight _ formula weight - mass in grams equal to formula weight (ionic) Gram molecular weight - mass in grams equal to molecular weight of the _ Gram grams Gram compound Oxidation-reduction (redox) reactions Oxidation - _ of electrons by an atom Reduction - _ of electrons by an atom _ agents - substances taking electrons from other substances (oxygen, chlorine) _ agents - supply electrons to oxidizing agents (hydrogen, carbon) loss gain Oxidizing ReducingĢ5 Chemical Reactions Atoms are conserved – Atoms do not get used up in a _ reaction Burning a piece of paper is a combustion reaction The atoms in the paper and the _ in the air react to form the ash, smoke, and the CO2 that exist after the reaction occurs Mass is _ – Same number and type of atoms, same mass is present Law of combining volumes (gases) Gases at the same temperature and pressure contain equal numbers of molecules chemical oxygen conservedĢ8 Units of Measurement Used with Chemical EquationsĪtomic mass unit = 1 a.m.u. Replacement reactions - Single ion replaces another ion in a compound Ion exchange reactions - Two cations switch places in their compoundsĢ2 AB + CD AD + CB Positive ions change/swap which anion they are bonded with (i.e. Products - substances existing _ reaction Word representation only is not precise Chemical symbols and formulas needed for _ purposes before after quantitativeġ7 Balancing equations Law of conservation of mass - atoms are neither _ nor destroyed in chemical reactions Mass of the products = Mass of reactants No mass defect, like with nuclear reactions Any _ released was stored in the bonds! Change _ in front of chemical formulas, not _ within formulas, to balance created energy coefficient subscriptsĢ0 Types of Reactions Decomposition reactions Combination reactions _ 1.56 3.125 1.56 1 1.56 2 SO2 Sulfur dioxideġ4 Chemical reactions Occur through formation and _ of chemical bonds between atoms Involve changes in matter, creation of _ materials and _ exchanges Chemical equations - concise _ of chemical reactions breaking new energy representationsġ5 Chemical equations Reactants - substances existing _ reaction S /_ = _ O / _ = _ The products will be the subscripts of the empirical formula. _ 0.1 0.05 2 0.05 0.05 1 Na2Oġ3 Empirical Formulas Divide each mass percentage by the mass numberĭivide the quotient of each element by the smallest quotient. ![]() Na /_ = _ O /_ = _ The products will be the subscripts of the empirical formula. atomic mass smallest decimal subscripts wholeġ2 Empirical Formulas Divide each mass by the atomic massĢ.3g Na / 23 = _ 0.8 g O/ 16 = _ Divide the quotient of each element by the smallest quotient. The empirical formula should be the simplest _ number ratio of the subscripts. The answers will be the _ of the empirical formula. If you have a _ such as 0.5, multiply all quotients by 2 0.25 multiply by 4, and 0.33 multiply by 3. Divide the number of each element you just found by the _ number you just found. _ of atomic weights of all atoms in chemical formula Molecular weight Formula weight of a _ substance Term often used for non-molecular (_) substances Total sum molecular ionicįinding the mass percentage of an individual _ from the formula weight elementĭivide the percent composition or mass of each element by their _. empirical _ metallic 1.7 Covalent other nonmetals CH2O ![]() Ionic - lacking discrete unit, or molecule Composed of _ and nonmetallic elements Electronegativity difference > _ Molecular _ compounds Usually nonmetals bound to _ Molecular and empirical formulas can be different Glucose – molecular C6H12O6 vs. Represents _ of atoms within a molecule Related to _ structure of molecule arrangement 3 – D Molecular formula Identifies _ number of atoms in a molecular compound Example: water, H2O Glucose _ Not table salt, NaCl (ionic compound) ratio H2O exact C6H12O6ģ Chemical Formulas 3. Identifies elements present in terms of simplest whole number _ Examples: table salt, NaCl water, _ 2. Presentation on theme: "Unit 11: Chemical Reactions"- Presentation transcript:Ģ Chemical Formulas 1.
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