Exploring Chemical Reactions & Fractals Assessment Key
1. Identify any clues in the experiment described below that indicate a chemical
reaction may have occurred.
Scientists took 15mL of one liquid and mixed it with 35mL
of a different liquid. A yellow solid began forming in the
liquid mixture. The mixture cooled down from 20ºC to 4ºC
during the first 10 minutes after being mixed.
A new substance in the form of a yellow solid formed. A
solid that forms in solution as the result of a chemical
reaction is called a precipitate.
The temperature of the solution decreased indicating heat
energy had to be absorbed for the reaction to proceed. Heat
was a reactant and the reaction should be classified as
endothermic.
2. What kinds of atoms can form an ionic bond?
a) Two metal atoms
b) Two nonmetal atoms
c) One metal and one nonmetal atom
d) One nonmetal and one semi-metal atom
3. What kinds of atoms can form a covalent bond?
a) Two metal atoms
b) Two nonmetal atoms
c) One metal and one nonmetal atom
d) One nonmetal and one semi-metal
4. A simple equation often used to represent the formation of rust is
4Fe + 3 O2  2Fe2O3
a) Is iron a metal or nonmetal? metal
b) Is oxygen a metal or nonmetal? nonmetal
c) What kind of bond exists between iron and oxygen in the compound that
forms? A covalent bond.
Exploring Chemical Reactions & Fractals
Assessment Key
http://MathInScience.info
©MathScience Innovation Center 2007
5. Use the periodic table to decide which of the following compounds are ionic and
which are covalent. Place yes or no in the columns to the right of each compound
to indicate which type of bond forms.
Formula
CaCl2
CO2
Al2O3
MgS
NaF
AsI3
Covalent Bonding
No
Yes
No
No
No
Yes
Ionic Bonding
Yes
No
Yes
Yes
Yes
No
6. Some chemical reactions are exothermic because
a) the substances are mixed in a sealed container.
b) there is not enough energy stored in the bonds of the reactants to form the
product(s).
c) there is more energy stored in the bonds of the reactants than is needed to
form the product(s).
d) the reaction vessel is heated on a hot plate.
7. A friend in another science class overhears you talking about fractals and asks
what a ‘fractal’ is and why fractals are important to scientists. Record your
response below.
Fractals are geometric figures just like rectangles, squares and
circles but fractals have irregular shapes and surfaces that cannot
be measured and analyzed using traditional methods and tools.
Fractals are composed of patterns that are continuously repeated
such that as you increase the magnification the smaller structures
look like the whole. For example, a head of cauliflower looks like
one of the individual florets.
Random behavior of atoms and molecules at a microscopic scale
sometimes leads to the formation of these complex predictable
patterns at the macroscopic scale that we identify as fractals.
Studying the patterns formed or measuring the fractal dimension of
these structures helps scientists understand and predict natural
phenomena such as stream and coastal erosion, fingering
instabilities during oil extraction and the diffusion of drugs within
the human body.
Exploring Chemical Reactions & Fractals
Assessment Key
http://MathInScience.info
©MathScience Innovation Center 2007