Chem-ME-stry Dichotomous Key Activity
Background:
A dichotomous key is a tool that can be used to easily identify things (usually living organisms).
Dichotomous means “divided into two parts.” A dichotomous key consists of a series of two part
statements that describe characteristics. At each step of a dichotomous key the user is presented with
two choices. As the user makes a choice about a particular characteristic, they are led to a new branch
of the key. Eventually, the user will be led to the name or identity of whatever that they are trying to
identify.
Purpose:
The purpose of this assignment is to create your own dichotomous key of matter in order to demonstrate
how characteristics and their relationships shape identity. In addition, you will also show how you are
connected to chemistry by including yourself in your own dichotomous key.
Your Task:
1. Develop a list of at least 10 different examples of matter or processes that involve matter. YOU
(or humans in general) must be one example. You should also have other examples of elements,
compounds, and mixtures or processes. Come up with your own OR If you need ideas, use your
periodic table OR consider some of the many examples we’ve mentioned/seen in class, such as:
Vinegar
Baking soda
Cornstarch
Water
Oxygen
Hydrogen
Nitrogen
Gold
Silver
Carbon
Sodium
Chlorine
Sodium chloride
Carbon dioxide
Glucose
Hydrogen peroxide
Saltwater
Kool-Aid
Soda
Salad
Sand
Soil
Brass
Air
Steel
Diamond
Quartz
Wax
Glass
Rubber
Molasses
Syrup
Rubbing Alcohol
Calcium chloride
Ammonium chloride
Magnesium
Hydrochloric acid
Ammonia
Copper sulfate
Dextrose
Paper
Dry ice
Burning wood
Melting butter
Filtering
Tarnishing
Baking a cake
Photosynthesis
2. Carefully examine and think about the characteristics of each example in your list. If needed, you
can always research some of the characteristics of your examples.
3. Then, like we did at the very beginning of this unit, develop a dichotomous key in the traditional
written format:
a. Consider your entire list. Separate everything into two groups based on a single
distinguishing characteristic. Record this characteristic.
b. Then, continue to separate each of the groups, recording the defining characteristics as
you go, until each example has its own separate set of characteristics.
1.a. Is a teacher on the 2nd floor of JM…………....go to step 2
b. Is NOT a teacher on the 2nd floor of JM………MR. DUFFY
2.a. Teaches science……………………..…go to step 3
b. Does NOT teach science………………MR. EASTMAN
3.a. Only teaches 8th grade………………...MS. DELONG
b. Teaches grades other than 8th…………go to step 4
4.a Only teaches 7th grade………………. go to step 5
b. Teaches grades other than 7th ………. MS. HAYNES
5a. Only teaches Life Science …………..............MS. TUCKER
b. Teaches subjects other than Life Science……MS. BOYCE
4. From your written dichotomous key, draw a spider key that visually illustrates the
relationships and identities for each item in your list, as shown below:
ESMS Teachers
NOT on 2nd floor of JM
On 2nd floor of JM
MR. DUFFY
Teaches science
Does NOT teach science
MR. EASTMAN
Teaches only 8th grade science
Teaches other science grades
Teaches grades other than 7th
MS. DELONG
MS. HAYNES
Only teaches 7th grade
Life Science only
MS. TUCKER
Other subjects
MS. BOYCE
Finished Product
1. Please type your finished, traditionally-written dichotomous key.
2. Neatly draw or type your finished spider web
3. Find a professional and creative way to display 1 and 2 above.
Additional Hints
Consider the vocabulary we have learned so far in our chemistry unit. Try incorporating these
terms into your dichotomous key.
Matter
Element
Atom
Compound
Chemical Bond
Mixture
Homogeneous mixture
Heterogeneous mixture
Physical properties
Chemical properties
Solid
Amorphous solid
Crystalline solid
Liquid
Viscosity
Gas
Physical changes
Chemical changes
Endothermic reaction
Exothermic reaction
Due Date
On or before Friday, February 20tj
Grading Rubric
Melting
Freezing
Vaporization
Boiling
Evaporation
Condensation
Sublimation
A DICHOTOMOUS KEY
THAT “MATTERS”