Materials for Life Professor Lynn Cominsky Joanne del Corral Sharon Janulaw Michelle Curtis July 9,...

Materials for Life

Professor Lynn Cominsky

Joanne del Corral

Sharon Janulaw

Michelle Curtis

July 9, 2003

NBSP Physical Science Leadership Institute

7/9/2003 Prof. Lynn Cominsky 2

Standard Connections Students know properties of solid, liquid

and gaseous substances, such as sugar (C6H12O6), helium (He), and Oxygen (O2), nitrogen (N2) (5)

Students know the common properties of salts, such as sodium chloride (NaCl) (5)


First Activity: Sugar and Salt How are sugar and salt different? If we couldn’t taste them, how could we

tell which is which?


Sugar and salt investigations:

Given: quantities of sugar & salt, and all the equipment that you have been using during the past two weeks

Can you predict how the physical properties of sugar and salt might differ?

Can you design experiments to differentiate between sugar and salt?


Key concepts about Sugar

Sugar is a type of carbohydrate and the most common molecules found in plants and animals

Carbohydrates are literally Carbon that is hydrated Carbon + water

C6H12O6 is glucose Other common sugars:

– sucrose C12H22O11

– fructose C6H12O6

All sugar names end in “ose” as do other carbohydrates


Structure of Glucose


Key concepts about Salt In its simplest form, Salt is a molecule

that pairs one element from the first group in the periodic table (e.g., Na) with an element from the seventh group (e.g., Cl)

Group 1 elements have one unpaired electron in their outer shells, while Group 7 elements are missing an electron to complete their outer shells


Key concepts about Salt Salts can be formed by mixing an acid

and a base to form a salt and water For example: Hydrochloric acid +

Sodium Hydroxide table salt + water

HCl + NaOH NaCl + H2O In solutions, salt dissociates into Na+

and Cl- ions – Na+ has lost one electron – Cl- has gained one electron

Ionic solutions can conduct current


Structure of NaCl


Second activity: Comparing gases

Helium, Nitrogen and Oxygen are all commonly occurring gases

Consult the periodic table to compare the properties of these gases

Can you draw pictures of the structure of each gas?

Consult the materials in your binder to compare the uses of these gases


Key concepts: Common gases Helium is a Noble gas – it is the second

most common element in the Universe but is only present in trace amounts in the Earth’s atmosphere

Nitrogen and Oxygen are diatomic gases which are rare in the Universe but – 78% of the atmospheric volume is nitrogen– 21% of the atmospheric volume is oxygen

They are both very chemically reactive


Structure of Common Gases:N2

Nitrogen gas is a diatomic molecule formed from two atoms of Nitrogen.

Each atom has 7 electrons. The inner shell is filled with 2 of these electrons, leaving a total of 5

electrons that try to fill the next shell (which holds 8) for each atom. A triple covalent bond between the two nuclei shares 3 pairs of the

electrons. Two other electrons are individually bonded to each nucleus.


Structure of Common Gases:O2

Oxygen gas is a diatomic molecule formed from two atoms of Oxygen. Each atom has 8 electrons. The inner shell is filled with 2 of these electrons, leaving a total of 6

electrons that try to fill the next shell (which holds 8) for each atom. A double covalent bond between the two nuclei shares 2 pairs of the

electrons. Four other electrons are individually bonded to each nucleus.


Vocabulary Salt: ionic molecule that pairs a group 1

and a group 7 element Sugar: molecule that combines Carbon

with an integral number of water molecules

Ion: elemental form with extra or missing electrons

Noble gas: an element in Group 8, which has a filled outer shell and is chemically (rather) inert


ELD Activities: Visual Imagery

Make a slide show, or have images ready to show to the students.

Ask them to first write down on a piece of paper or in their journal whether the object shown is a liquid, a solid, or a gas.

Then ask volunteers to give their answer.


Publisher’s Materials

Take some time to look through the state-adopted texts to find activities relating to commonly occurring substances, such as sugar, salt and atmospheric gases


Break – something to think about

Why do you think the relative abundances of helium vs. nitrogen/oxygen are so different between the Universe and the Earth’s atmosphere?


Standard Connections

Students know atoms and molecules form solids by building up repeated patterns, such as the crystal structure of NaCl or long-chain polymers. (8)


Third Activity: Structure of Solids

Given: toothpicks, styrofoam balls Use the toothpicks to represent electrons in

the outer shells Use the styrofoam balls to represent the

nuclei of the various elements Create models for NaCl, Glucose, Nitrogen

gas and oxygen gas Compare the models – what are the structural

differences between Sugar and Salt? Between N2 and O2?


Key concepts: Structure of Sugars

Sugars come in many forms– Monosaccharides – glucose, fructose– Disaccharides - sucrose– Polysaccharides – made of many smaller

glucose type rings Polysaccharides include starch,

glycogen and cellulose


Structure of Solids: Polymeric Molecules

Starch is made of many units of glucose

Numbered corners are C-H (not shown)

This is (a small part of) amylose 4000 units of glucose


Further investigations: Slime!

Given: Borax, white glue, water, food coloring, ziploc bag

Add 1 Tbsp. Borax to 1 cup water, stir until dissolved

Make a solution of ¼ cup water and ¼ cup glue – mix thoroughly

In a ziploc bag, add equal parts borax solution and glue solution

Add a couple of drops of food coloring Seal bag and knead mixture Dig in and have fun!


Further questions:

What are the properties of slime? How can we tell that this is a polymer? What other polymers do you know?


Key concepts: Structure

Ionic crystals such as salt, have a regular lattice structure

Repeating units in salt are cubic in shape – the molecule is also cubic

Sugars have units that can repeat to make complex carbohydrates such as starch

Repeating units are cyclic in shape – the overall molecule is chain-like


Vocabulary

Polymer – complex molecule made of repeating units in a chain-like structure

Crystal – molecular structure made of repeating units in a cubic structure

Saccharide – sweet substance Starch – polysaccharide that is used for

energy storage in plants Glycogen – polysaccharide that is used

for energy storage in animals


ELD Activities: Analogies and Student Involvement

Have the students investigate their favorite food and snacks.

Ask them to look at the “Ingredient List” on the label of the food packaging and list all the words ending in “ose” in their journal.

Go over the words with them the next day. (A hint on health awareness might be welcome there as well!)



Take some time to look through the state-adopted texts to find activities relating to structure of common molecules

Examples: MH p. 221


Lunch – some things to think about

How do sugars and starches provide energy for plants and animals?


Standard Connections Students know how to determine whether a

solution is acidic, basic or neutral (8)


Fourth Activity: Cabbage Juice Science

Make your own acid/base indicator by boiling red cabbage.

Use the juice to test whether different fluids are acids or bases.

Compare the pH results from the cabbage juice to those obtained using litmus paper.


Equipment for Cabbage Juice activity red cabbage juice vinegar and lemon juice baking soda, powdered lime, and liquid soap some plastic spoons, stirring sticks, and 4 plastic cups 5 medicine droppers 1 marker


Cabbage Juice Activity: Label 6 clear plastic cups with numbers 1-6 Fill all cups up ~1/4 of the way with cabbage juice. Collect your five samples

– Vinegar– Lemon juice– Baking soda– Powdered lime– Liquid soap (non-antibacterial)

Place a small amount of each sample into each of five of the plastic cups.

If your sample is an acid, it will turn the cabbage juice pink. If your sample is a base, it will turn the cabbage juice green.


Further investigations:

Label 2 clear plastic cups: 1 and 2 Fill all cups up ~1/4 of the way with water. Place one known acid and one known base

into each of the cups. Place a piece of litmus paper into each of the

cups. Basic solutions will turn red litmus paper blue

and will leave blue litmus paper unaffected. Acidic solutions will turn blue litmus paper red

and will leave red litmus paper unaffected.


Key concepts: pH

Acidic solutions contain an excess of protons or H+. pH is a measure of how 'acidic' a solution is. The lower the pH, the more acidic the solution.

In chemical terms, pH means "the negative log of the concentration of protons" in solution. Chemistry students should recognize this as pH = -log[H+].


Key concepts: pH

"Neutral" solutions (e.g.,water) have a pH of 7. This number coincides with the amount of H+ naturally formed in water from the equilibrium reaction:

H2O H+ + OH- "Basic" solutions have a pH greater

than 7, meaning that they have less free H+ than that in neutral water.


Key concepts: pH Red cabbage contains pigments call

anthocyanins. The pigments give it the red/purplish color. Anthocyanins belong to group of chemical compounds called flavonoids.

Other plants that contain anthocyanins include beets, cranberries and blueberries.


Vocabulary pH: A measure of the acidity or alkalinity of a

solution, numerically equal to 7 for neutral solutions. The pH scale commonly in use ranges from 0 to 14.

Base: Any of a class of compounds whose aqueous solutions are characterized by a bitter taste, a slippery feel, the ability to turn litmus blue, and the ability to react with acids to form salts.

Acid: Any of a class of substances whose aqueous solutions are characterized by a sour taste, the ability to turn blue litmus red, and the ability to react with bases and certain metals to form salts.


ELD Activities: Visual imagery and student involvement

Form groups of 14 students. Have all students wear an “H+ sign”. Draw a circular boundary (one per

group) on the ground and ask each group to make “acidic, neutral, or basic solutions” by adding, or removing “H+s (represented by each student) using the pH scale as a reference.



Take some time to look through the state-adopted texts to find activities relating to pH, acids and bases.

Examples: HM p. C78


Break – some things to think about

Do you think pH would be a useful test to discriminate between sugar and salt?

Why or why not?


Standard Connections Students know living organisms and most

materials are composed of just a few elements (5)


Fifth Activity: Essential elements in living organisms

Review the handout in the binder that includes many tables summarizing the elemental abundances in different locations

How many elements are essential to plants? To animals?

How do the abundances change from the Universe to the solar system?


Fifth Activity: Essential elements in living organisms

How do the abundances change from the solar system to the atmosphere?

How do the abundances change from the atmosphere to the oceans?

How do the abundances change from the oceans to the crust?

How do the abundances change from the crust to plants?


Further investigations:

What do these changes tell you about the evolution of life in the Universe?


Key concepts: Essential Elements

Light elements (H and He) dominate the early Universe

As the solar system formed, heavier elements (made in stars) were incorporated to make the planets

The atmosphere is about ¾ N2 and ¼ O2

There are a limited number of elements that are essential to plants and animal life, including H, C, N and O.


Vocabulary

Abundance: relative amount of an element


ELD Activities: Compare and Contrast Table A

Write down examples of living organisms. Remember you are a living organism!

Find or draw a picture of the living organisms you found

List all elements this organism or material needs in order to survive (i.e. water)


ELD Activities: Compare and Contrast Table B

Write down examples of materials

Find or draw a picture of the materials you found

List all elements this organism or material needs in order to keep form (i.e. Carbon)


Questions for ELD Tables:

1. Using table A and B, list the common elements you see in living organisms and materials:

2. What does this tell you about living organisms and

most materials? Are they similar in any ways?



Take some time to look through the state-adopted texts to find activities relating to the elements that are essential to plants and animals


Take away – brain teaser

What do you think the gases are that make up the atmospheres of the “gas giant” planets such as Jupiter and Saturn?


Lesson Study Activities

Identify a key concept from today’s lecture for further development

Review the publisher’s materials about this key concept

Think about the best way to present this key concept in your classroom


Resources

Physics by Inquiry – L. McDermott and the PEG at U Washington

http://www.saltinstitute.org/15.html http://www.brooklyn.cuny.edu/bc/ahp/SDPS/SD.PS.ions.html http:// biology.clc.uc.edu/graphics/ bio104/glucose%20alone.jpg

http://www.greenspirit.org.uk/resources/glucose.gif http://www.elmhurst.edu/~chm/onlcourse/chm110/molimages/N2.GIF

http://www.poemsinc.org/oceano/abund.htm

Date post:	28-Dec-2015
Category:	Documents
Upload:	jonathan-collins
View:	222 times
Download:	0 times

Materials for Life Professor Lynn Cominsky Joanne del Corral Sharon Janulaw Michelle Curtis July 9,...

Documents