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Sometimes I pretend to be normal, but then it gets boring, so I go back to being me.

Sometimes I pretend to be normal, but then it gets boring, so I go back to being me. Is it possible to vary the ratios of the components?. YES. NO. MIXTURE. PURE SUBSTANCE. Does it appear uniform throughout?. Only one kind of atom?. YES. NO. YES. NO. HOMOGENEOUS. ELEMENT.

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Sometimes I pretend to be normal, but then it gets boring, so I go back to being me.

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  1. Sometimes I pretend to be normal, but then it gets boring, so I go back to being me.

  2. Is it possible to vary the ratios of the components? YES NO MIXTURE PURE SUBSTANCE Does it appear uniform throughout? Only one kind of atom? YES NO YES NO HOMOGENEOUS ELEMENT HETEROGENEOUS MOLECULE

  3. A PHASE CHANGE IS A PHYSICAL CHANGE. FOR EXAMPLE, MELTING, BOILING, FREEZING, CONDENSATION. YOU ARE NOT CHANGING CHEMICAL COMPOSITION – NO CHEMICAL BONDS ARE BROKEN AND NO CHEMICAL BONDS ARE FORMED.

  4. WE USE CHEMICAL SYMBOLS TO REPRESENT ATOMS OF DIFFERENT ELEMENTS. FOR EXAMPLE, H FOR HYDROGEN Na FOR SODIUM Cl FOR CHLORINE WE USE COMBINATIONS OF SYMBOLS, FORMULAS, TO REPRESENT MOLECULES.

  5. A MOLECULE IS THE SMALLEST UNIT OF A COMPOUND – IT IS TWO OR MORE ATOMS CHEMICALY COMBINED (HELD TOGETHER BY CHEMICAL BONDS). EXAMPLES OF FORMULAS: H2O – WATER – THIS TELLS US THAT FOR EVERY MOLECULE OF WATER, WE HAVE TWO ATOMS OF HYDROGEN AND ONE OF OXYGEN. THE SUBSCRIPT AFTER THE SYMBOL TELLS US HOW MANY ATOMS OF THAT ELEMENT ARE PRESENT IN THE MOLECULE.

  6. OTHER EXAMPLES: CH4 METHANE (NATURAL GAS) C6H12O6 GLUCOSE (BLOOD SUGAR) NaCl SODIUM CHLORIDE (TABLE SALT) C10H14N2 NICOTINE THERE ARE OTHER WAYS OF REPRESENTING MOLECULES. THESE ARE SIMPLE FORMULAS AND DO NOT TELL US HOW THE ATOMS ARE JOINED.

  7. IF YOU PUT A NUMBER IN FRONT OF A FORMULA, THAT TELLS YOU HOW MANY MOLECULES YOU HAVE. FOR EXAMPLE: 2H2O - TWO MOLECULES OF WATER THE TWO WOULD MULTIPLY EVERYTHING IN THE FORMULA BY TWO. YOU WOULD HAVE A TOTAL OF 4 HYDROGENS AND 2 OXYGENS.

  8. THERE ARE SEVERAL DIFFERENT KINDS OF FORMULAS. STRUCTURAL FORMULAS SHOW HOW THE ATOMS ARE ARRANGED. WATER STRUCTURAL FORMULA WATER SPACE FILLING MODEL, SHOWING ELECTRON CLOUDS

  9. CHEMISTS USE FORMULAS IN EQUATIONS TO SHOW CHEMICAL REACTIONS: CH4 + 2O2 2H2O + CO2 THE EQUATION TELLS US THAT ONE MOLECULE OF METHANE WILL REACT WITH 2 MOLECULES OF OXYGEN TO YIELD 2 MOLECULES OF WATER AND ONE MOLECULE OF CARBON DIOXIDE. THE NUMBERS OF ATOMS OF EACH TYPE WILL BE THE SAME OF BOTH SIDES OF THE EQUATION.

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