2. BILL NYE THE SCIENCE GUY
http://www.youtube.com/watch?v=PlwuxpMh8nk
3. 7.1: DESCRIBING REACTIONS The most useful way of describing
reactions (or a chemical change) is by stating what was present
before and after the chemical change.
4. CHEMICAL CHANGE chemical reaction process in which one or
more substances are changed into new substances reactants substance
that reacts product the new substance that is formed
5. CONSERVATION OF MASS The French chemist Antoine Lavoisier
established that the total mass of the products always equals the
total mass of the reactants. This is called the Law of Conservation
of Mass (mass is not created nor destroyed in a chemical
reaction).
6. WRITING EQUATIONS chemical equation shorthand method to
describe a chemical reaction using chemical formulas and other
symbols Reactants HgO(s) Products Hg(l) + O2(g)
7. WRITING EQUATIONS (aq) aqueous (substance dissolved in
water) (s) solid (l) liquid (g) gas coefficients the numbers to the
left of the formulas used to help balance the equation
8. BALANCING EQUATIONS If you notice that the number of atoms
on the left side does not equal the number of atoms on the right
side then we must balance the equation. Since mass is conserved
before and after a chemical reaction, an equation MUST BE balanced
in order for it to be true.
9. BALANCING EQUATION RULES 1. You should NEVER change the
subscripts in a formula. 2. Start by, counting the number of atoms
of each element on each side of the equation. 3. Change one or more
coefficients until the equation is balanced
10. EXAMPLE Balance the following equation NiCl2(aq) + NaOH(aq)
Ni(OH)2(s) + NaCl(aq)
11. EXAMPLE HgO(s) Hg(l) + O2(g)
12. 7.2: TYPES OF REACTIONS Reactions are classified by the
type of reactant or the number of reactants and products. There are
4 different types of reactions that we will discuss Synthesis
Decomposition Single-Replacement Double-Replacement
13. SYNTHESIS A synthesis reaction is a reaction in which two
or more substances react to form a single substance. The product
synthesized is always a compound Examples A + B AB 2Na + Cl2
2NaCl
14. DECOMPOSITION The opposite of synthesis A decomposition
reaction is a reaction in which a compound breaks down into two or
more simpler substances. The reactant MUST BE a compound. Examples
AB A + B 2H2O 2H2 + O2
15. SINGLE REPLACEMENT A single replacement reaction is a
reaction in which one element takes the place of another element in
a compound. Example Form: A + BC B + AC Cu + 2AgNO3 2Ag +
Cu(NO3)2
16. DOUBLE REPLACEMENT A double replacement reaction is one in
which two different compounds exchange positive ions and form two
new compounds. Example Forms: AB + CD AD + CB Pb(NO3)2 + 2KI PbI2 +
2KNO3
17. 7.3: ENERGY CHANGES IN REACTIONS Chemical Energy the energy
stored in the chemical bonds of a substance. Chemical Reactions
involve the breaking of chemical bonds in the reactants and the
formation of chemical bonds in the products.
18. BREAKING BONDS Breaking Bonds REQUIRES energy. This means
we need to ADD energy in order to break the bonds of reacting
molecules in order to get the reaction started.
19. FORMING BONDS The formation of chemical bonds RELEASES
energy. When new chemical bonds are formed, a bit of energy is
released usually in the form of heat or light.
20. ENERGY IN REACTIONS During a chemical reaction, energy is
either ABSORBED or RELEASED. We describe these reactions in two
different ways either Exothermic or Endothermic.
21. EXOTHERMIC REACTIONS A chemical reaction that RELEASES
energy is called an exothermic reaction. The energy released as the
products form is greater than the energy required to break the
bonds in the reactants. Think of it as energy is EXITING the
reaction EXiting _ Exothermic
22. ENDOTHERMIC REACTIONS A chemical reaction that absorbs
energy from its surroundings is called an endothermic reaction.
This means that there is more energy require to break the bonds of
the reactants than is released by the formation of the
products.
23. CONSERVATION OF ENERGY The total amount of energy BEFORE a
reaction is EQUAL to the total amount of energy AFTER a reaction.
This is called the Conservation of Energy.
24. 8.1: FORMATION OF SOLUTIONS A solution is a mixture that
forms when substances dissolve and form a homogeneous mixture In
order for a solution to form, one substance must dissolve in
another.
25. DISSOLVING Every solution has two components A solute is a
substance who particles are dissolved in a solution A solvent is
the substance in which the solute dissolves in. There are three
ways that substances can dissolve into water: dissociation,
dispersion, ionization
26. DISSOCIATION In order for a solution to form, the
attractions that hold the solute together and the solvent together
must be overcome. The process in which an ionic compound separates
into ions as it dissolves is called dissociation. Example: Sodium
Chloride & Water
27. DISPERSION Sugar dissolves into water by dispersion, or
breaking into small pieces that spread throughout the water.
Example: Sugar & Water
28. IONIZATION The process in which molecules gain or lose
electrons is known as ionization. Example: Ions are formed by the
reaction of the solute and solvent particles.
29. PROPERTIES OF LIQUID SOLUTIONS Conductivity: ability to
conduct electric current Boiling Point: temperature needed for
solution to change from liquid phase to gas phase Freezing Point:
temperature needed for solution to turn from liquid phase to solid
phase. Solutions can also be described as endothermic or exothermic
depending upon whether energy is released or absorbed.
30. 8.2: SOLUBILITY & CONCENTRATION The maximum amount of
solute that dissolves in a given amount of solvent at a constant
temperature is. called solubility Depending upon the amount of
solute in a solution, solutions can be described as either
saturated, unsaturated or supersaturated.
31. SATURATED A saturated solution is one that contains as much
solute as the solvent can hold at a given temperature.
32. UNSATURATED A solution that has less than the maximum
amount of solute that can be dissolved is called an unsaturated
solution.
33. SUPERSATURATED A supersaturated solution is one that
contains more solute than it can normally hold at a given
temperature. Usually very unstable.
34. FACTORS AFFECTING SOLUBILITY Polarity of the solvent like
dissolves like Solution formation is more likely to happen when the
solute and solvent are either both polar or both nonpolar.
Temperature The solubility of a solids increases as the solvent
temperature increases Pressure Increasing pressure on a gas
increases solubility in a liquid.
35. CONCENTRATION The concentration of a solution is the amount
solute dissolved in a specified amount of solution. Can be
expressed as percent by volume, percent by mass and molarity.
36. SOLUBILITY CURVE Each line on the graph is called a
solubility curve for a particular substance. You can use a
solubility curve to figure out how much solute will dissolve at any
temperature given on the graph.
37. 10.1: RADIOACTIVITY Henri Becquerel 1896 left uranium salt
in a drawer with a photographic plate when he developed the plate,
he found an outline of the clumps of the uranium salt he
hypothesized that the uranium salt emitted some sort of energy
Marie and Pierre Curie students of Becquerel 2 years later, they
discovered Po and Ra while studying uranium ore pitch blende
38. THEY DISCOVERED Radiation release of matter and energy from
nucleus Light energy (electromagnetic spectrum) all forms of
radiation
39. STRONG FORCES Protons are held together by strong forces
short range force as the distance increases, the force weakens
causes protons and neutrons to be attracted to each other
40. STRONG FORCES to hold a nucleus together tightly, the
nucleus can decay and give off matter and energy stable nucleus
stays together permanently unstable nuclei radioactive!!!! nucleus
does not stay together; emits matter and energy
41. RADIOACTIVE ELEMENTS radioactivity the process of nuclear
decay elements after #83 are radioactive all elements after #92 are
synthetic and decay soon after they are created
42. REVIEW !!!!!!! Mass number = # protons + # neutrons Atomic
number = # of protons Example (12 = mass #) (6= atomic #) 12 6
C
43. REVIEW: ISOTOPES most elements have at least one
radioactive isotope isotope same element with a different number of
neutrons Example: Carbon-12 (stable) Carbon-14 (unstable)
44. RADIOACTIVE DECAY Transmutation the process of changing one
element into another through nuclear decay Radioactive decay occurs
until a stable nucleus is formed
45. ALPHA DECAY alpha decay () releases alpha particle (a
helium nucleus) a helium nucleus consists of 2 protons and 2
neutrons atomic mass is 4 atomic number is 2 4 2He Ex: 238 92 U 234
90 Th + 4 2He
46. BETA DECAY Beta Decay () release beta particle it occurs
when a neutron breaks down into 1 electron and 1 proton the result
is an atom with 1 more proton Ex: 14 6 C 14 7 N+ 0 e -1
47. PRACTICE: ALPHA & BETA DECAY 214 84 222 86 214 82 234
92 Po Rn Pb U 210 82 Pb ______ ______ 4 2 ______ 0 1 234 93 Np He e
______
48. NUCLEAR REACTIONS FISSION process of splitting a nucleus
into several smaller nuclei
49. NUCLEAR REACTIONS FUSION: Two nuclei with low masses are
combined to form one nucleus of larger mass
50. HALF LIFE half-life the amount of time it takes for half
the nuclei in a sample of the isotope to decay the nucleus left
after the isotope decays is called the daughter nucleus some
half-lives are seconds, others are millions of years
51. EXAMPLE: HALF LIFE Assume a 20g sample of Ba-139 has a
half-life of 86 minutes. how much Ba-139 remains after 86 minutes?
after 172 minutes? how many lives leave 1.25g of Ba-139?
