Grade 7 Science Chapter 7 Notes o262b

Grade 7 Science Unit 3 Matter can be classified as mixtures or pure substance

Chapter 7

The Story of Archimedes

*Read Story 228-229

Review: Particle Theory of Matter 1. All matter is made up of tiny particles. 2. These particles are always moving... they have energy 3. There are spaces among particles. 4. There are attractive forces between the particles. 5. The particles of one substance differ from the particles of other

Mini-Partner Activity 1 Together think of examples for each, then answer the following 2 questions. Pure Substance

Mixture

1. How would you tell the difference between a pure substance and a mixture? ______________________________ ______________________________ ______________________________ ______________________________ ______________________________ ______________________________

1. How would you tell the difference between a pure substance and a mixture? __See (the properties) if you can see the different parts, (different states, different_ colour, texture, etc). A pure substance should be the samethroughout____________

2. How would use the Particle Theory of Matter to your answer to question #1? _______________________________ ______________________________ ______________________________ ______________________________ ______________________________ _____________________________

2. How would use the Particle Theory of Matter to your answer to question #1?

___A pure substance has its own kind of particle, that are different than___ other substances particles. That____ means it should have the same____ properties throughout___________

Mixtures Vs. Pure Substances How many visible Parts?

Mixtures

Pure Substances

May have more Have ONLY one than one visible part visible part (not always - think salt/sugar water)

Mixtures Vs. Pure Substances Uniform Througout?

Mixtures

Pure Substances

MAY appear ALWAYS appear as uniform throughout. uniform throughout

Mixtures Vs. Pure Substances Definition?

Mixtures They are the physical combination of two or more pure substances.

Pure Substances They contain either a single particle or two or more atoms chemically combined to form a different substance.

Mixtures Vs. Pure Substances Examples

Mixtures •salt water, •kool-aid •chocolate chip cookie •muddy water •salad dressing •air

Pure Substances •sugar (C12H22O11) •gold (Au), •copper (Cu) •distilled water (H2O) •carbon dioxide (CO2) •oxygen (O2)

Mixtures Vs. Pure Substances Drawing of Particles

Mixtures

Pure Substances

*Can be this, just as long as all the particles are the same throughout

Mini-Partner Activity 2 Read pages 232, 236, and 237. Make a list of 15-20 solutions and mixtures that you encounter in a day. Put a * those that may pose a safety risk.

Soltions Vs. Mixtures! Solutions

Mixtures

Practice Questions (Homework) Pg 237 Q’s 1,2 &3

Read Page 242 - Complete the Following Flow Chart

Homogeneous vs. Heterogeneous Mixtures

Homogeneous

Heterogeneous

solutions

also called mechanical mixtures

Also called?

Homogeneous vs. Heterogeneous Mixtures

States of Matter?

Homogeneous

Heterogeneous

solid, liquid or gas

can be solid, liquid or gas

Homogeneous vs. Heterogeneous Mixtures Homogeneous Particles?

Heterogeneous

the particles are evenly mixed none the particles do of the original not evenly mix substances are visible

Homogeneous vs. Heterogeneous Mixtures Homogeneous # of visible parts?

they appear to be ONE substance

Heterogeneous

the different parts are visible to the eye (may need a microscope)

Homogeneous vs. Heterogeneous Mixtures

How does light ?

Homogeneous

Heterogeneous

light es through unaffected

Light will reflect Perpendicular to the direction of the beam

Homogeneous vs. Heterogeneous Mixtures Homogeneous Examples ● ● ● ● ●

Kool-aide Salt water Vegetable oil Pure air Stainless steel frying pan

Heterogeneous ● ● ● ● ● ●

Granola Bar Concrete Beach Salad Dressing Computer Smog-filled air

The Tyndall Effect Light can be used to distinguish between solutions and what appears to be a solution •cannot be used to distinguish between a solution and a pure liquid

The Tyndall Effect In a Solution/homogeneous: Light es unaffected (looks at the beaker perpendicular to the direction of the beam they will NOT see it)

The Tyndall Effect In a Mechanical Mixture/heterogeneous: The light will scatter as it es through the mixture because all particles are not dissolved (look perpendicular to direction of the beam and you WILL see it!)

Partner Activity List the various homogeneous and heterogeneous mixtures in your home. Homogeneous

Heterogeneous

Mini-Lab: Compare Milk, OJ and Soda Pure or Mixture? Pg. 238-239 Are they solutions or mixtures? Homogeneous or Heterogeneous? Did the extra magnification change you mind?

Chapter Review Questions: Page. 250-251: 1, 2, 4, 6 & 8