PS Spring Final
Study Guide Answers
Ch. 16 Objectives
Describe how the chemical energy in fossil fuels is
converted into electrical energy.
• Chemical potential energy in fossil fuels is burned,
releases thermal energy, thermal energy reacts with
water to form steam, steam turns a turbine, turbine
spins a generator/transformer, energy sent to
consumers through power lines
• Some energy is lost along the way in the form of heat
Discuss nuclear fusion as a possible energy source.
• Fusion = combining of hydrogen atoms into helium
• Not useful because it requires high temperatures to
occur, high temps are hard to maintain, ends up using
more energy than it makes
Analyze the need for alternative energy
sources.
• Fossil fuels are nonrenewable and will run out
at some point
• Harmful to the atmosphere, releasing CO2,
Describe alternate methods for generating
electricity.
• Burn fossil fuels, Burn biomass, Nuclear
power, solar, hydroelectric, windmills,
geothermal, tidal energy
Ch. 18 Objectives
Define pure substances and mixtures.
• Pure substance – type of matter with
fixed/definite composition, all the atoms are the
same, element & compound
• Mixture – 2 or more substances that can be
separated by physical means
Identify elements and compounds.
• Elements – pure substances in which all atoms
have the same identity
• Compounds – 2 or more different elements
combine in a fixed proportion
Compare and contrast physical and chemical
changes.
• Physical changes – doesn’t change the
identity, sometimes its reversible
• Chemical changes – changes the identity,
creates something new
Determine how the law of conservation of
mass applies to chemical changes.
• Law = mass is neither created nor destroyed
• Mass stays the same
Ch. 19 Objectives
Identify the names and symbols of common
elements.
• Use periodic table
• Oxygen = O, Carbon = C, hydrogen = H, Ne =
Neon, Ti = Titanium, B = Boron, Al = Aluminum
Describe the electron cloud model of the atom.
• Area around the nucleus is where electrons are
likely to be found, electrons move so quickly it is
hard to pinpoint their location
• Current model of the atom
Compute the mass number of an atom.
• Protons + Neutrons = mass number
• Average Atomic Mass = look on the periodic
table
Identify the components of isotopes.
• Atoms of the same element (same # of
protons) with different number of neutrons
(changes the mass #)
• Most elements have more than 1 isotope
Use the periodic table to obtain information.
• Periodic table = arrangement of elements
• Developed by Mendeleev
• Can obtain = atomic weight, atomic number (# of
protons), group and period, chemical symbol, state of
matter, name,
Explain what metals, nonmetals and semi-metals are
and where they are located on the periodic table.
• Metals = left side of table, shiny, good conductors, solid
• Nonmetals = right side of table, brittle, poor
conductors, most are gases
• Semi-metals/metalloids = found on staircase,
properties of metals and nonmetals
Ch. 22 Objectives
Describe how a compound differs from its component
elements.
• Different chemical and physical properties
• NaCl = safe to eat, Na = reacts violently with water, Cl =
toxic gas
Discuss why chemical bonding occurs.
• Elements form bonds to achieve stability
• Gain, lose, or share electrons to be stable
• Stable # of electrons = 8 (Outer shell/valence electrons)
• Noble gases = don’t form compounds readily because
they have a full valence shell of 8 electrons
Describe ionic and covalent bonds.
• Ionic = when ions attract due to their opposite
charges
– Ions, good conductors, gain or lose electrons =
ions
– Metal & nonmetal
• Covalent = when atoms share electrons to
form a molecule
– 2 nonmetal
Write formulas and names for ionic
compounds.
• Name of Positive ion name of negative with –
ide at the end
• Sodium chloride
• Ammonium hydroxide
• When naming transition metals, you must
determine their charge and indicate that using
roman numerals
– (Ex. Copper (I) oxide)
• K3P = potassium phosphide
Write formulas and names for covalent
compounds.
• USE GREEK PREFIXES
• Prefix-Name of Positive ion prefix-name of
negative with –ide at the end
• H2O = dihydrogen monoxide
• Carbon tetrafluoride = CF4
Ch. 23 Objectives
Identify the reactants and products in a
chemical reaction.
• Reactants = compounds/elements that are put
together, left side
• Products = compounds/elements made, right
side
Determine how a chemical reaction satisfies
the law of conservation of matter.
• Everything is equal
• Same # of atoms of each element on each side
Using coefficients, balance chemical equations.
• Coefficients = big numbers, precede symbols and formulas to
indicate number of that compound or element
Identify the general types of chemical reactions.
• Decomposition – one reactant breaks down into 2+ products,
AB  A + B
• Synthesis – A + B  AB, 2+ reactions combine to form 1
product
• Single-Replacement – one element replaces another in the a
compound, A + BX  AX + B
• Double-Replacement – 2 elements switch places, precipitate
forms, 2 ionic compounds produced, AX + BY  AY + BX
• Combustion – type of synthesis, fire, CxHy + O2  CO2 + H2O
Compare and contrast endothermic and
exothermic reactions.
• Exothermic = releases heat to outside
• Endothermic = absorbs heat, add heat to the
reaction
Describe the factors that affect reaction rate.
• Catalyst/Inhibitor
• Temperature – increase temp = speeds up the reaction
• Surface Area – break substance down into smaller parts
(more surface area exposed) = speeds up the reaction
• Concentration – higher concentration of atoms =
speeds up the reaction because more collisions
• Discuss the effects of catalysts and inhibitors on the
speed of chemical reactions
• Catalyst = something added to a reaction that remains
unchanged, speeds up the reaction
• Inhibitor = stops or slows down the reaction