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Classification of Matter. Elements Compounds Mixtures. Compounds. A substance made up of two or more different elements joined by chemical bonds. 4 Properties of Compounds. 1 . The properties of the elements that make up the compound change.
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Classification of Matter Elements Compounds Mixtures
Compounds A substance made up of two or more different elements joined by chemical bonds
4 Properties of Compounds 1. The properties of the elements that make up the compound change
*Properties of individual elements are different*than the resulting compound table salt = White granular Reacts explosively with water Is a poisonous gas Safe and used in many foods we eat
2. Elements that make up a compound must be present in exact amounts
TableSugar Must Have in it: 12 Carbon Atoms C12H22O11 11 Oxygen Atoms 22 Hydrogen Atoms If this sugar molecule did not have the exact amount of each element, then it would not be a sugar molecule.
Combustion of Methane Gas Photosynthesis (sunlight) CH4 + 2O2 CO2+ H2O CO2 + H2O C6H12O6 (glucose) + O2 When you combine methane gas with oxygen through combustion, the result is carbon dioxide gas and water with heat energy given off When plants combine carbon dioxide with water, and sunlight energy is taken in, they produce glucose and oxygen
Molecule Smallest part of a substance that still has all the characteristic properties of that substance
C12H22O11 A combination of symbols and numbers to represent a compound Chemical Formula Chemical formula for Sugar
Subscripts • A dropped number after a symbol of an element in a formula that tells how many atoms of that element are in the compound C12H22O11 Sugar has 22 Hydrogen atoms Sugar has 12 Carbon atoms Sugar has 11 Oxygen atoms
Chemical Equation • A representation of a chemical reaction that uses symbols to show the relationship between the reactants and the product(s) HCl + NaOH NaCl + H2O Product Reactants
Reactants Substances before the arrow in the equation that are combined HCl + NaOH NaCl + H2O Reactants
Products Substances produced because of a reaction; after the arrow in the equation HCl + NaOH NaCl + H2O Product
Coefficient • A number that is placed at the beginning of a formula to represent how many molecules of that compound are present in the equation 2H2O This number “2” tells us that we need two water molecules
Law of Conservation of Mass • Matter can neither be created nor destroyed during a chemical reaction (The equation must balance) HCl + NaOH H2O + NaCl 2 Hydrogen atoms 1 Chlorine atoms 1 Sodium atom 1 Oxygen atom 2 Hydrogen atoms 1 Chlorine atoms 1 Sodium atom 1 Oxygen atom