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Chapter 14 Chemical Reactions
Forming New Substances
O ___________ -a process in which one or more substances change to make _____________________ ______________O The ________ and ________ _________of the new
substance _______ from those of the original substances.
O Examples of chemical changes: O O
Signs of a Chemical Reaction
O O O O formation of a solid ___________O _____________- Solid substance that
is formed in a solution
Signs of a Chemical Reaction
O A change of properties:O The signs can help you identify a
chemical reaction, but they do not guarantee a reaction took place. O Ex. Boiling water gives off gas, but this
is a physical change.O The most important sign that a
chemical change took place is the _______________ ____________________________________.
Chemical BondO_____________ -force that holds two atoms
together in a molecule. The original bonds must _______ and new bonds must be ______.O Ex 1: H2 and Cl2
O Chlorine gas has a greenish-yellow colorO Hydrogen gas is flammableO Hydrogen chloride is a nonflammable, colorless gas.
O Ex 2: Na and Cl2O Na is a metal that reacts violently with waterO Cl is a greenish-yellow poisonous gasO Sodium chloride is a harmless substance that almost
everyone uses.
Ch 14.2 Chemical Formulas and Equations
O ______________ - a shorthand way to use ________________ and ___________ to represent a substance. It shows how many atoms of each kind are present in a molecule.
Chemical Formulas and Equations
O Subscript- number written below and to the right of a chemical symbol in a formula.O *If no subscript is present, it means only 1
atom of that element is present.O Ex: H2O H = O =
C6H12O6 C = H= O=
CO2 C = O =
Writing formulas for Covalent Compounds
O composed of 2 nonmetals
O use prefixesO if there is only one
atom of the first element
drop the mono- prefixO change 2nd elements
suffix to –ideO Ex: CO2
N2O
Mono- 1
Hexa- 6
Di- 2
Hepta- 7
Tri- 3
Octa- 8
Tetra- 4
Nona- 9
Penta- 5
Deca- 10
Writing formulas for Ionic Compounds
O composed of a metal and a nonmetalO put the metal first, nonmetal second
overall charge must be 0. O charges of the ions will cancel out
O criss-cross ruleO change suffix of nonmetal to –ideO Ex: NaCl
MgCl2
Chemical EquationsO _______________ - chemical symbols
and formulas as a shortcut to describe a chemical reaction
O ____________ - the starting materials in a chemical reaction
O ____________ -the substance formed from a reaction
O Ex: C + O2 CO2
How do new substances form in a chemical reaction?
O 1. O Molecules are always moving O If molecules bump into each other
with enough energy, the chemical bonds in the molecules break.
O 2. O 3.
The Reason Equations Must be Balanced:
O ·Atoms are never ____ or _______ in a chemical reaction
O ·They are just _____________
O ·The # of atoms in the __________ must __ # of atoms in the ___________O This is called
balancing the reaction
Law of Conservation of Mass
O ___________________ -Mass is neither created or destroyed in ordinary chemical and physical changes
How to Balance an Equation:
O You must use ___________- number placed in front of a chemical symbol or formula
O Ex 1: 2CO means ____________________________O Ex 2: 2H2O means ___________________________
O Total there are __ hydrogen atoms and __oxygen atoms
O ·Only coefficients are changed when balancing equations – ________________!!
O ___H2 + ___O2 ___H2O | | |
Balancing Chemical Reactions
____ Na + ____Cl2 → ____NaCl
Na Na O O
____ N2 + _____ H2 → ____ NH3
N N H H
14.3 Types of ReactionsO_____________- A
reaction in which two or more substances combine to form one new compound.O A + B = ABO Ex: Sodium + Chlorine
= Sodium Chloride
Synthesis Reaction
Types of ReactionsO ______________ -A reaction in which a
single compound breaks down to form two or more simpler substances.O AB = A + BO Ex: Carbonic Acid = Water and
carbon Dioxide
Decomposition Reaction
Types of ReactionsO _______________________ -
A single element replaces another element that is part of a compound. O Products are a new
compound and a different single element
O O Ex:
O *The more reactive element can displace a less reactive element.
O Ex: Copper can replace Silver, but the opposite can’t occur.
Single Replacement
Types of ReactionsO _____________________-
A reaction in which ions from two compounds switch places.
O AB + CD = AD + CB
O EX:
Sodium Chloride + Silver Fluoride = Sodium Fluoride + Silver Chloride
Double Replacement
14.4 Energy and Rates of Chemical Reactions
O ________________________- Reaction in which energy is released. O EXO means “__________”O Ex: 2Na + Cl2 2NaCl + ________
O ________________________ - Reaction in which energy is taken inO ENDO means “__________”O Ex: 2H2O + _________ 2H2 + O2
Law of Conservation of Energy
O_______________________________ - Energy cannot be created or destroyed
O Energy can be _____________ from one object to another
O_________________ - the speed at which new particles form
O__________________ - The smallest amount of energy that molecules need to react.
Factors that Affect Reaction Rate
O _________________ – the higher the temperature, the faster the reaction rate
O _________________- The higher the concentration of reactants, the faster the reaction rate
O ________________ - (amount of exposed surface on a substance) The larger the surface area, the faster the reaction rate
O ______________- A substance that slows down a reaction. Ex: Preservatives in food slow down bacteria growth.
O ______________- A substance that speeds up a reaction without being permanently changed. NOT A REACTANT!! Ex: Enzymes speed up reactions in your body.
