a draft of a chemistry lesson on the 6- sided crystal structure of snowflakes, as related to water molecule structure and hydrogen bonding. Note that water VAPOR condenses directly into ice crystal snowflakes, with no liquid phase between the vapor and solid phases.

1. SNOWFLAKES
can help us see why ice floats in water.
A Ten- Minute
Highly Differentiated
Grade 9 Chemistry Lesson
Nicole Gall, email appleforteacher@hotmail.com; website
www.mrsgallscience.wikispaces.com; twitter @appleforteacher

2. GLCEs
 P.PM.01.21 Demonstrate that water as a solid keeps its
own shape (ice).
 P.PM.01.22 Demonstrate that water as a liquid takes on
the shape of various containers.
 P.PM.04.23 Compare and contrast the states (solids,
liquids, gases) of matter.
 P.CM.06.11 Describe and illustrate changes in state, in
terms of the arrangement and relative motion of the
atoms or molecules.
 P.CM.06.12 Explain how mass is conserved as it changes
from state to state in a closed system.
 P.PM.07.23 Illustrate the structure of molecules using
models or drawings (water, carbon dioxide, salt).

3. HSSCEs: Chemistry
PREREQUISITES
 P2.p1A Describe energy changes associated with
changes of state in terms of the arrangement and order
of the atoms (molecules) in each state. (prerequisite)
 P2.p1B Use the positions and arrangements of atoms
and molecules in solid, liquid, and gas state to explain
the need for an input of energy for melting and boiling
and a release of energy in condensation and freezing.
(prerequisite)
 P4.p1A For a substance that can exist in all three
phases, describe the relative motion of the particles in
each of the phases. (prerequisite)

4. HSSCEs: Chemistry
PREREQUISITES
 P4.p1B For a substance that can exist in all three
phases, make a drawing that shows the arrangement
and relative spacing of the particles in each of the
phases. (prerequisite)
 P4.p1C For a simple compound, present a drawing that
shows the number of particles in the system does not
change as a result of a phase change. (prerequisite)
 P5.p1A Draw a picture of the particles of an element or
compound as a solid, liquid, and gas. (prerequisite)

5. HSSCEs: Chemistry
HIGH SCHOOL CURRICULUM
 C2.2A Describe conduction in terms of molecules
bumping into each other to transfer energy. Explain why
there is better conduction in solids and liquids than
gases.
 C2.2B Describe the various states of matter in terms of
the motion and arrangement of the molecules (atoms)
making up the substance.
 C3.3A Describe how heat is conducted in a solid.

6. HSSCEs: Chemistry
HIGH SCHOOL CURRICULUM
 C3.3B Describe melting on a molecular level.
 C4.3B Recognize that solids have a more ordered,
regular arrangement of their particles than liquids and
that liquids are more ordered than gases.
 C5.5c Draw Lewis structures for simple compounds.

7. Special emphasis
 C2.2B Describe the various states of
matter in terms of the motion and
arrangement of the molecules (atoms)
making up the substance.
 P5.p1A Draw a picture of the particles of
an element or compound as a solid, liquid,
and gas. (prerequisite)

8. Handouts:
 Pretest, Pencils
 Coffee Filters, Scissors
 Notes Page or Lesson Brochure
 Key Concepts written on paper
 Writing passage with blanks for Key Concepts
 Tape or glue sticks
 Posttest, Coffee Filters
Collect: Scissors, Tape or Glue Sticks

9. PRETEST
1. Are snowflakes considered solid, liquid, or gas (vapor)?
2. How many sides does a snowflake have?
3. Does ice sink or float in liquid water?
4. Of solids, liquids, and gases, which is hottest?
5. Of solids, liquids, and gases, which is coldest?
6. Of solid, liquid, and gas (vapor) WATER, which is the
MOST DENSE (D = m/v; density is a measure of how
“tightly packed” the particles are within a substance)?
7. Of solid, liquid, and gas (vapor) WATER, which is the
LEAST DENSE ?
8. Remove the small labeled square on the bottom left side
of this page. Fold and cut this small piece of paper to
create a snowflake shape.

10. KEY CONCEPTS AND
VOCABULARY
 SOLID
 LIQUID
 VAPOR (GAS)
 DENSITY
 ARRANGEMENT
 MOTION
 CRYSTAL
 PARTICLES
 SUBSTANCE
 MOLECULES

11. KEY CONCEPTS
AND
VOCABULARY
•SOLID
•LIQUID
•VAPOR (GAS)
•DENSITY
•ARRANGEMENT
•MOTION
•CRYSTAL
•PARTICLES
•SUBSTANCE
•MOLECULES

12. KEY CONCEPTS
AND
VOCABULARY
•SOLID
•LIQUID
•VAPOR (GAS)
•DENSITY
•ARRANGEMENT
•MOTION
•CRYSTAL
•PARTICLES
•SUBSTANCE
•MOLECULES

13. Fill in the blanks using key
concepts.
 A ……..……….is a collection of particles. These ………..……
may be a mixture or all the same; they may be single
atoms or……..……… If the particles vibrate or wiggle,
within a locked …………….pattern, the substance is
a………..…... Particles in faster…………...., which flow
around each other, no longer locked into place,
are………..……. Faster moving molecules bounce
vigorously, filling the entire space of the container. This
is the ………..…….state. The ……….……..of water molecules
depends on their motion: vibrating, flowing, or bouncing.
The …..………...… of water also depends on the
arrangement of the molecules within the solid, liquid, or
vapor substance.
 Substance. Particles. Molecules. Crystal. Solid. Motion. Liquid. Vapor
(gas). Arrangement. Density.

14. Fill in the blanks using key
concepts.
 A substance is a collection of particles. These particles
may be a mixture or all the same; they may be single
atoms or molecules. If the particles vibrate or wiggle
within a locked crystal pattern, the substance is a solid.
Particles in faster motion, which flow around each other,
no longer locked into place, are liquid. Faster moving
molecules bounce vigorously, filling the entire space of
the container. This is the vapor (gas) state. The
arrangement of water molecules depends on their
motion: vibrating, flowing, or bouncing. The density of
water also depends on the arrangement of the molecules
within the solid, liquid, or vapor substance.

17. POST- TEST
1. Are snowflakes considered solid, liquid, or gas (vapor)?
2. How many sides does a snowflake have?
3. Does ice sink or float in liquid water?
4. Of solids, liquids, and gases, which is hottest?
5. Of solids, liquids, and gases, which is coldest?
6. Of solid, liquid, and gas (vapor) WATER, which is the
MOST DENSE (D = m/v; density is a measure of how
“tightly packed” the particles are within a substance)?
7. Of solid, liquid, and gas (vapor) WATER, which is the
LEAST DENSE ?