Quiz 4 Review: Complete this review sheet, in addition to studying the material on the
chemical reactions website (activities 1­3) to prepare for the quiz on Friday. Use the
QR code to get to the website. The review sections of the website contain additional
review questions.
Radioactive Decay:
What part of the atom is involved in radioactive decay?
The nucleus­ decay involves changes to protons and neutrons.
Identify the types of decay shown below:
__Alpha Decay__
Beta Decay__
Gamma Decay__
What happens during alpha decay?
2 protons and 2 neutrons are emitted from the nucleus.
The atomic number (number of protons) and the atomic mass decreases.
Which form of radioactive decay is the most dangerous?
Gamma decay­ high energy (short wave length and high frequency) is emitted.
What is an isotope?
Atoms of the same element with the same atomic number but different atomic mass.
Carbon­12 (6 protons, 6 neutrons)
Carbon­14 (6 protons, 8 neutrons)
What is the half life of carbon­14 according to the graph below?
5700 years
If the half­life of strontium­90 is 25 years, how much of a 100 gram sample will be left after 50 years?
25yrs (1 half­life) 25yrs (2nd half­life)
100g ­­­­­­­­­­­­­­­­­­­­­­> 50g ­­­­­­­­­­­­­­­­­­­­­­­­> 25g
Solutions vs. Suspensions:
Identify whether or suspension or solution will form:
Description
Solution or suspension?
Example
Polar solute in a polar solvent
solution
salt in water
Polar solute in a nonpolar solvent
suspension
sugar in oil
Nonpolar solvent in a nonpolar solvent
solution
oil and flour
Nonpolar solute in a polar solvent
suspension
flour in water
How do temperature, agitation, and surface area affect the formation of a solution?
Temperature­ Higher temperatures will increase the speed at which a solution forms because it
increases kinetic energy which makes particles move faster. Faster moving particles will be more
likely to collide with each other.
Agitation­ Shaking a mixture will increase the speed at which a solution forms because when shaking
a mixture the particles move faster which will increase the likelihood of collisions. Increasing collisions
will increase the likelihood of attraction between particles.
Surface area­ Increases the number of sides available for the molecules of a solvent to interact with
the molecules of a solute.
What is the difference between a physical and chemical change? What is the rule to remember?
Physical­ no new substance forms. Usually a change in the appearance of a substance (size, shape,
mass etc).
Chemical­ new substance forms.
Determine which of the following is a physical change and which is a chemical change?
Breaking glass
Physical (start with glass end with glass)
Nailing boards together
Physical (one piece of wood connected to
another­ no new substance)
Spoiling food
Chemical (smell and discoloring of food
indicates the presence of a new substance)
corroding metal
Chemical (discolored nail due to rust formation
indicates chemical change)