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Monday, March 22, 2010

Apologia Physical Science, Module 4, The Wonder of Water

Interactive Study Links
• Making flashcards at is a great way to study!  Create an account to be able save your flashcard sets to practice every day.  You can make cards for whatever you need to study in the chapter, not just vocabulary.  Here are some examples, but be careful if you use these; some have had errors.  You will learn a lot more if you make your flashcards yourself.
Hydrogen Bonds Animation - short fun animation

Other Study Links
How to read a meniscus - why it can be difficult to get an accurate measurement
Penny/Paperclip Lab - love the fill-in sheet at the end
Hydrogen Bonding and the boiling point of water, and how water (H2O) behaves differently than other H2__ substances (H2S, H2Se, and H2Te -- and these are mentioned in the texbook).
Snow Globe Lab - really cool, and if you don't want to actually make snow globes, you can simply let the class experiment and see which solvents dissolve which solutes, and to learn about the polar and non-polar properties.
Surface Tension, Cohesion, Adhesion - great information, and love the examples section.
• Module 4 Practice Page - created by Debbie
►See most of these and more at Debbie's Educator's Resources.  (Thanks, Debbie!)

Also thanks to Debbie for her hard work in locating about half of these videos and posting them on her class website.  So glad I found her last year!  =D

(1) p. 81-84, The Composition of Water

(2) p. 85, Chemical Formulas

Chemical symbols:
     hydrogen: H     oxygen: O     carbon: C     sodium: Na     chloride: Cl

Chemical Formulas:
     water: H2O     carbon dioxide: CO2     table salt (sodium cloride): NaCl

(3) p. 86-89, Water's Polarity

Sharing electrons is what causes atoms to "stick" together to become molecules.

Sharing Electrons

Because water molecules are polar, see this image to understand how water molecules in a stream of water will "flip" so that their positive ends are attracted toward the negative charges on a balloon that has been rubbed in your hair, causing the stream of water to bend.  (image source)

(4) p. 90-93, Water as a Solvent

Atoms generally have the same number of protons (positive) and electrons (negative), and therefore have no net electrical charge.  (Is neither more positive or more negative)
Atoms cannot gain or lose protons, but they can gain or lose electrons.
If an atom gains/loses electrons, it has an imbalance of charges and is now an ion.

Sodium ions have lost an electron, and are positive.
Chloride ions have gained an electron and are negative.
Sodium Chloride (table salt - NaCl) is an ionic molecule.

In a saltwater solution, water is the solvent, and salt is the solute.
Since water is polar, it is able to dissolve salt.  Polar solvents can dissolve either polar or ionic solutes.
Nonpolar solutes can only be dissolved by nonpolar solvents.

(5) p. 93b-97, Hydrogen Bonding in Water

Chemical bonding links atoms together to form molecules.
Hydrogen bonding links molecules together.
Chemical bonds are stronger than hydrogen bonds.  You can boil water to break the hydrogen bonds, unlinking the molecules, but the chemical bond still holds the molecules together - a water vapor, or gas, of microscopic water molecules.

Water cannot hydrogen bond when it is in a solid state - ice!
That is why water is expanded when frozen and why it floats -- its molecules are further apart than when a liquid, so ice is less dense than water.

• Hydrogen Bonds Animation - short fun animation
• Hydrogen bond image

Properties of Water

More about hydrogen bonding.

Water Molecules - part 1 is a great video animation that shows that water molecules are polar, and will hydrogen bond.  Hydrogen bonding is what enables water to stay in a liquid form at room temperature (instead of a gas like other H2__ substances).

Water Molecules - part 2 shows the state of water molecules in liquid form, as a solid, and as a gas.

(6) p. 97b-99a, Water's Cohesion

Surface tension is caused by cohesion.

It would be cool to drink that glob of water, haha!
(And how different can two people's hair be??? Love hers... but his...?  He needs gravity, lol.) =D

cohesion - how water sticks to itself
adhesion - how water sticks to other things

Mercury has very little adhesive properties, but strong cohesion.

(7) p. 99b-100, Hard Water and Soft Water

From Wikipedia:
"In chemistry, a solution is a homogeneous mixture composed of only one phase. In such a mixture, a solute is a substance dissolved in another substance, known as a solvent. The solvent does the dissolving. The solution more or less takes on the characteristics of the solvent including its phase, and the solvent is commonly the major fraction of the mixture. The concentration of a solute in a solution is a measure of how much of that solute is dissolved in the solvent."
Read full article.  Really good!


  1. Hi! I am creating my own page with videos, etc, from your page and a few other places. I haven't decide if I'll post it or just leave it for my eyes only at this point. I just want to have the things I'll use with my daughter all in one place. But, if I do post it, I'll give you credit!

    Thanks for posting all of these wonderful resources. This is making a HUGE difference in what we learn this year!

  2. Hello, Dana!
    You're welcome, and thank you for the comment.
    It is really neat to be able to create our own posts in the order/manner we like, isn't it? I love it. =)
    And thanks for the credit. And if you make yours public, please do let me know. I'd love to see what you do. =)

  3. You have done such a terrific job. I am here again this year, using your wonderful resources! Thank you for you kindness of sharing :)

    1. You're welcome, Mary! I first started this for my kids, and have been pleasantly surprised at the many that are able to use it. Thanks for letting me know!! =) =)


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