SCIENCE EXPERIMENTS VARIABLES (DESIGNING AN EXPERIMENT) 3 TYPES OF VARIABLES 3 TYPES OF VARIABLES 2/8/2017

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1 SCIENCE EXPERIMENTS VARIABLES (DESIGNING AN EXPERIMENT) SNC1DB Most experiments in science are controlled studies: experiments which look at the relationship between two variables Variable: any factor, trait, or condition that can exist in differing amounts or types 3 TYPES OF VARIABLES 1)Independent variable (IV) change/ cause -The independent / manipulated variable -The variable which the experimenter deliberately changes or adjusts 3 TYPES OF VARIABLES 2) Dependent variable (DV) outcome/ result -The outcome / responding variable -The variable in which the experimenter is interested in or studying NOTE: There will only be one IV and one DV *The IV and DV are always found in the question/ purpose!* 1

2 3 TYPES OF VARIABLES 3) Control Variables (CV) -Variables that we do not change in the experiment -They could change but are NOT allowed to Ask the question: What does the scientist have to do in order for this to be a fair test? 2 TYPES OF OBSERVATIONS 1) Qualitative Observations descriptions of qualities of objects and events, without reference to a measurement or number - using your 5 senses 2) Quantitative Observations measurements or counting - using instruments (e.g. ruler) LEARNING GOALS I will be able to classify matter into their appropriate categories. I will identify characteristic physical properties of pure substances. 5.1 FROM PARTICLES TO SOLUTIONS SNC1DB 2

3 SUCCESS CRITERIA PARTICLE THEORY OF MATTER Explain the main ideas of the particle theory of matter. Describe the difference between a pure substance and a mixture. Describe the difference between a mechanical mixture and a solution. Explain the composition of an alloy Matter is made up of anything that has mass and takes up space. Different kinds of matter are made up of different kinds of particles. Particle theory of matter: a theory that describes the composition and behavior of matter. 1. All matter is made up of tiny particles that have empty spaces between them. 2. Different substances are made up of different kinds of particles. 3

4 3. Particles are in constant random motion. 4. The particles of a substance move faster as its temperature increases. 5. Particles attract each other. Attractive forces are stronger when particles are closer together. STATES OF MATTER Adding or taking away heat can cause the particles of matter to increase or decrease their random motion. Changes of state are caused by temperature changes (i.e. energy change) 4

5 CHANGES OF STATE melting: changing from a solid to a liquid (ice turning to water) solidification: changing from a liquid to a solid (water freezing) evaporation: changing from a liquid to a gas (a puddle disappears on a hot day) condensation: changing from a gas to a liquid (drops of water forming on a cold glass in the summer) sublimation: changing from a solid to a gas (dry ice disappearing) deposition: changing from a gas to a solid (the formation of frost) CHANGES OF STATE ionization: when an atom or molecule acquires a positive or negative charge (occurs with other chemical changes) deionization: removal of ions; particles move slowly and come together CHANGES OF STATE CLASSIFICATION OF MATTER Matter can be classified or grouped based on different characteristics. 5

6 CLASSIFICATION OF MATTER PURE SUBSTANCES CLASSIFICATION OF MATTER - MIXTURES PURE SUBSTANCES PURE SUBSTANCES: ELEMENTS AND COMPOUNDS Pure substance: a substance that is made up of only one type of particle (atom or compound) -Examples: distilled water, helium gas Element: a pure substance that cannot be broken down into simpler parts by chemical methods. - Found on the periodic table Compounds: are pure substances made of two or more elements that are chemically combined. A compound can be broken down into its elements by chemical methods. 6

7 MIXTURES Mixture: a substance that is made up of at least two different types of particle. - Mixtures can be either solids, liquids or gases. - Examples: salt water, granola bar MIXTURES: MECHANICAL MIXTURES AND SOLUTIONS Mechanical mixture: - Can see different types of matter - Different samples may have different makeup Solution: - Cannot see the difference between types of matter - Different samples look exactly the same ALLOYS Alloy: a solid solution of two or more metals - a subclass of a solution Examples: Solder used to join together metal components such as wires and electrical circuits, made out of tin and lead Silverware made of various alloys and is electroplated for appearance and resistance 7

8 HOMEWORK 1. Complete Control Variables worksheet 2. Complete Qualitative vs. Quantitative worksheet 3. Read pg , Answer ps. 178#1-10 8