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Compounds, Molecules, Chemical Reactions and Balancing Equations

Compounds, Molecules, Chemical Reactions and Balancing Equations. IPS Ch. 6 CPS Ch. 19. Elements. Matter that has only one type of atom Atomic Number = # of Protons Atomic Mass = Protons + Neutrons Atomic Symbol First letter is always CAPITOL, second letter always lower case.

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Compounds, Molecules, Chemical Reactions and Balancing Equations

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  1. Compounds, Molecules,Chemical Reactions and Balancing Equations IPS Ch. 6 CPS Ch. 19

  2. Elements • Matter that has only one type of atom • Atomic Number = # of Protons • Atomic Mass = Protons + Neutrons • Atomic Symbol • First letter is always CAPITOL, second letter always lower case. Co (cobalt) is not same as CO (carbon monoxide)

  3. Mixtures • Mixtures of elements • Mixtures of compounds • Mixtures of Elements and Compounds • Example: Stainless steel • Mixtures of: • Iron • Chromium • Nickel • Carbon

  4. Compound H H O Definition: Molecule: Two or more atomschemically combine to form a new substance the smallest part of a compound. The atoms are tightly bonded together

  5. Chemical Formula (a compounds name) • Symbols of different elements of the compound • Examples: Salt: NaCl sodium chloride Na Cl WaterH2O di-hydrogen oxide C6H12O6 ???

  6. Di-atomic molecules Diatomic molecules are molecules composed of only two atoms, of the SAME elements. Hydrogen (H2) Nitrogen (N2) Oxygen (O2) Fluorine (F2) Chlorine (Cl2) Bromine (Br2) Iodine (I2)

  7. Making Compounds • Atoms combine in a chemical reaction to make a new substance - compound. Give some examples of chemical changes:

  8. How do you know if a chemical reaction has occurred? Color change (sometimes) Making Kool-Aid or boiling water are physical changes, NOT chemical changes Gas is released: odor, smoke (sometimes) Changes form: (sometimes) Gets hot!!! Heat energy is released exothermic NEW SUBSTANCE IS FORMED!! (cannot get subs. back) (Mass changes.)

  9. Naming Compounds Write the chemical name for each chemical formula for each compound. Use the following prefixes: Mono- one, di- two, tri- three, tetra- four, change the ending to -ide • CO _________________________________ • O2 _________________________________ • Dihydrogen oxide ___________________________ Carbon monoxide Di-oxide H2O

  10. Complete the chart by first identifying each substance by its chemical name. Then describe each substance by placing a CHECK in the appropriate box. oxygen X X X dioxide X X X

  11. Counting Atoms WS 4 H2O2 () Fill in the following tables with the correct number of atoms for each compound.

  12. Worksheet 19.1 “The Chemical Equation” Page 450-452 #1 through #8

  13. Chemical Reaction: • A NEW material is formed by the rearrangement, recombining of atoms • Chemical Equation (recipe for a reaction) • Shows a chemical reaction between materials C+ O2 CO2 molecule molecule atom Product(s) Reactants

  14. Chemical Reaction • Atoms Rearrange to form new substances

  15. Chemical Equation (Phases) C(s)+ O2(g) CO2 (g) • (s) =______________ • (l) =______________ • (g) =______________ • (aq) = Aqueous Solution (dissolved in water)

  16. Chemical Equation • Coefficients • Located in front of the element or compound • Number of molecules • Subscripts • Tiny numbers located after an element • Number of atoms 4NH3(g)+ 3O2(g) 2N2(g) + 6H2O(l)

  17. Finish WS 19.1 #9- #12

  18. Law of Conservation of Mass In ALL reactions, Mass (atoms)cannot be created or destroyed (added) (removed) Atoms are just rearranged, But the TOTAL MASS (atoms) must before the reaction must equal the total number of atoms after the reaction. Mass must remain the SAME!

  19. Identifying Balanced Equations Notes

  20. Identifying Balanced Equations Notes • 1. Count the # of atoms on each side of the equation. • 2. Circle if it is balanced or unbalanced. • 3. If unbalanced, then balance it by adding coefficients. 3. _2_ NiCl2 ___Ni + ___Cl2 Reactants Products ____________________ ____________________ ____________________ ____________________

  21. Balancing Equations Rules: 1. DO NOT change subscripts!!! • (Changing subscripts changes the chemical!) 2. Balance the atoms by CHANGING COEFFICIENTS to have the same # of atoms on both sides of the equation. 3. Total number of atoms in reactants = the total number of atoms in the products

  22. Balancing Equation Tips Tip #1: Order to balance hydrocarbon reactions First: Carbon Second: Hydrogen Third: Oxygen Tip #2: Rearrange if needed H2O can also be written as H(OH) Tip #3: To balance 2 and 3, use the lowest common multiplier - 6

  23. Balancing Equation Tips Tip #4: “Multiple Oxygen on one side” -Bar Oxygen on each side and add together C2H6 + O2 --> CO2 + H2O 2 + 2 = 4 5. 2 H2O + O2 2 H2O2 2 + 1 = 3

  24. Balancing Equation Tips Tip # 5 The most complicated ones are often the simplest to balance: __ Na2O2 + ___ H2SO4 --> ___ Na2SO4 + ___ H2O2 ____ Ba(OH)2 +  ___ H3PO4  -->   ___  BaHPO4  + ___ H2O 2

  25. Practice: Tip #3: To balance 2 and 3, use the lowest common multiplier - 6 __Fe(s) + __O2 (g) __Fe2O3 (s) Fe ___ Fe ___ O ___ O ___ Total ___ Total ___ 4 3 2

  26. Practice Problem 1 H2 + O2 H2O Reactant SideProduct Side H-________ H- ________ O-________ O- ________ BALANCED? NOT Balanced, the # of O’s on each side is not equal. TO BALANCE it? Coefficient #s must be added in front of the atoms or molecules to balance the equation.

  27. Practice Problem 2 Na2SO4 + CaCl2 CaSO4 + NaCl Na-________ Na- ________ S- ________ S- ________ O- ________ O- ________ Ca-________ Ca- ________ Cl-________ Cl- ________

  28. Practice Problem 3 Al2O3 Al + O2 Al- ________ Al- ________ O- ________ O- ________

  29. Practice Problem 4 C2H6 + O2  CO2 + H2O C- ________ C- ________ H- ________ H- ________ O- ________ O- ________

  30. Practice Problem 5 ___N2 + H2NH3 _______ _______ _______ _______ Draw a diagram of the atoms/molecules for the reaction:

  31. Balancing Equations Partner Worksheet

  32. Exit Slip 1. A chemical equation is balanced when: a) Products and reactants are the same chemicals b) Subscripts of the reactants equal the subscripts of the products c) Coefficients of the reactants equal the coefficients of the products d) The same number of atoms of each element appears on the reactant and product side 2. What are the two subatomic particles found in the nucleus? 3. Where is the most mass of an atom found? ____ Mg + ____ Fe2O3 ____ Fe + ____ MgO Type of reaction: _______________ ____ H2 + ____ O2 ____ H2O Type of reaction: _______________ ____ PbSO4 ____ PbSO3 + ____ O2 Type of reaction: _______________

  33. Exit Slip 1. ___N2 + H2NH3 2. What are the substances written to the right of the arrow in the chemical equation? 3. In the chemical equation, what does the “” mean? 4. How many elements are present in NH3? 5. In a neutral atom, the number of protons in the nucleus balanced by an equal number of • Neutrons • Electrons • Isotopes

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