chemistry notes chemical reactions & equations. signs of chemical reaction change in temperature...
TRANSCRIPT
CHEMISTRY NOTESCHEMICAL REACTIONS
& EQUATIONS
SIGNS OF CHEMICAL REACTION
• Change in temperature–1. ________________:
releases energy in the form of heat. You can feel it getting “hotter”
SIGNS OF CHEMICAL REACTION
• Change in temperature–2. _______________:
absorbs heat energy from the reactants. It feels “cooler” than it did at the beginning
SIGNS OF CHEMICAL REACTION
• Color change
• _______________ bubbles are seen forming or being released from the reaction
SIGNS OF CHEMICAL REACTION
• Solid Production- a new, solid substance forms. If a solid is formed in a solution, the solid is called a ___________________
SIGNS OF CHEMICAL REACTION
• A CHEMICAL REACTION HAS OCCURRED IF THE __________________________ OF THE REACTION ARE DIFFERENT FROM THE __________________________ OF THE REACTION
RULES OF CHEMICAL RXNS
• Starting chemicals, elements or substances are called ___________________, because they are going to react to form something new.
RULES OF CHEMICAL RXNS
• Ending chemicals, elements or substances are called ___________________, because they were produced in the reaction.
RULES OF CHEMICAL RXNS
• All the __________ found at the start of a reaction must be present at the end of a reaction.
RULES OF CHEMICAL RXNS
• This is the Law of _________________________
• All matter (measured as mass) in the _________ must be present in the ____________.
CHEMICAL BONDS
• A chemical bond occurs between _______________.
• Bonds only involve _________________________
CHEMICAL BONDS
• Electrons can be transferred between atoms–Called an _________ Bond–Example:
CHEMICAL BONDS
• Electrons can be shared between atoms– Called a __________ Bond–Example:
CHEMICAL FORMULAS
• A shorter, easier way of showing chemical reactions using symbols instead of words
• ________________ – shows the ratio of elements in a compound
CHEMICAL FORMULAS
• Subscript numbers behind a symbol tell how many atoms of that element there are in the substance.
CHEMICAL FORMULAS• Example: Hydrogen Peroxide’s
name means 1 Hydrogen for every 1 Oxygen.
• The formula is H2O2
CHEMICAL FORMULAS
• What does “Carbon Dioxide” mean?
What is its formula?
CHEMICAL FORMULAS
• What are other examples of formulas you can think of?
BALANCING EQUATIONS
• 1. Write the reaction in words.
• 2. Write the chemical equation.
BALANCING EQUATIONS
• 3. Count all of the atoms for each element on each side of the equation.
BALANCING EQUATIONS
• 4. Choose ___________ to place in front of each molecule to make each side of the equation balance.
Classifying Chemical Reactions
• Synthesis
• Decomposition
• Single Replacement• Double Replacement
Synthesis
• Two or more elements combine to form a more complex compound
• A + B AB
• Hand + kerchief handkerchief
• Example: C + Cl2 CCl4
Decomposition
• Breaks down compounds into simpler substances
• AB A + B
• Schoolbook school + book
• Example: Al2O3 Al + O2
Replacement
• A reaction in which one element replaces another in a compound, or two elements in different compounds trade places
• AB + C AC + B (Single)• AB + CD AC + BD (Double)