Chemical and Physical Properties and Changes

All substances have physical properties and chemical properties. Example: A log’s physical properties would include its mass, volume, density, the type of wood it came from… Properties and Changes (c) 2012 S. Coates

Properties and Changes All substances have physical properties and chemical properties. Example: A log’s chemical properties would include flammability (how likely it will be to burn). (c) 2012 S. Coates

Physical Properties When we observe or describe something or someone we use “drivers license” descriptions. Weight, Height, Eye Color, Hair Color, etc. We can observe or describe MATTER the same way. (c) 2012 S. Coates

Physical Properties Use physical characteristics to determine who I am… (c) 2012 S. Coates

Take 60 seconds and list as many physical properties as you can… (c) 2012 S. Coates

Physical Properties Physical Properties: used to observe or describe characteristics of matter. How would you observe or describe this object? Size Shape Density Materials its made of Color (c) 2012 S. Coates

Physical Properties Things you observe and can describe about matter: Color Size Freezing Point Melting Point Mass Shape Volume Density (c) 2012 S. Coates

Physical Properties Lab Visit each of the 12 stations and identify physical properties of the substances. Remember to use GOOD LAB SAFETY since some of the chemicals may be harmful. (c) 2012 S. Coates

Physical Properties Physical Properties DO NOT change the structure of matter when it is observed or described. What does “structure” mean? How the atoms are stuck or bound together! Each letter is a different atom, and the lines that connect the letters show the STRUCTURE of the substance. And here each color represents a different atom and this picture shows the STRUCTURE of the substance. (c) 2012 S. Coates

Physical Properties What is the “structure” of water? What is the “structure” of ice? What is the “structure” of steam? H2OH2O H2OH2O H2OH2O (c) 2012 S. Coates

Physical Properties We just observed one of the physical properties of H 2 O! PHASE CHANGE We observed of how H 2 O is different in each phase, but the structure of the H 2 O molecules never changed! (c) 2012 S. Coates

Physical Prop. and Changes When a physical property (like the phase of water) is altered we called it a PHYSICAL CHANGE In other words: A physical change makes a change to the APPEARANCE! It takes a physical change to change water to steam, or ice to liquid. (c) 2012 S. Coates

Water Phase Change Lab Materials Needed: – Water – 500 mL Beaker – Thermometer – Bunsen Burner or Electric Hot Plate If using a Bunsen Burner: Ring stand, ring, gauze pad, lighter, tubing, thermometer clamp (c) 2012 S. Coates

Experiment Set-Up

Water Phase Change Lab Procedure: 1.Fill your beaker with 300 mL water 2.Insert the thermometer and hold it or clamp it so that it is touching only the water (and NOT resting against the glass) 3.After 90 seconds, record the temperature of the water at time 0. (c) 2012 S. Coates

Water Phase Change Lab Procedure: 4. Light the Bunsen Burner or turn on the stove. 5. Record the temperature of the water every 30 seconds, for a total of 12 minutes. (c) 2012 S. Coates

More Examples of Physical Changes… (c) 2012 S. Coates

Physical Changes Shape The shape of the wood changes when you cut it into the shape of a bat. But it is still a piece of wood. (c) 2012 S. Coates

Physical Changes Shape The shape of the pencil tip changes when you put it in a sharpener. But it is still a pencil. (c) 2012 S. Coates

Physical Changes Size The size of paper changes when it is shredded. But it is still paper (c) 2012 S. Coates

Physical Changes Melting Point The ice cream melted. But does it still taste like ice cream? (c) 2012 S. Coates

Physical Changes You can think of Physical Changes like changing the font of a word… Basketball The “structure” of the words is still the same, even though the physical appearance changed. (c) 2012 S. Coates

Physical Changes Indicators that a Physical Change has occurred: –Phase change –Mixture (like Kool-Aid) –Shape / Size change –Expected Color Change (c) 2012 S. Coates

Which substance is salt? Sometimes physical properties cannot tell us the difference between substances. (c) 2012 S. Coates

Chemical Changes And you can think of Chemical Changes like rearranging the letters of a word… Basketball Let Blab Ask Lab Bat Elks Ask Bell Tab Stab Elk Lab Bask At Bell (c) 2012 S. Coates

Chemical Properties Chemical Properties describe the way a substance reacts with other substances. We can use chemical properties to tell us the difference between two similar looking substances. (c) 2012 S. Coates

Chemical Properties What are some examples of Chemical Properties? Flammability (Does it burn?) Oxidation (Does Oxygen change it?) Toxicity (Is it poisonous?) Radioactivity Sensitivity to Light Reactivity with water Reactivity with acid (c) 2012 S. Coates

Chemical Properties Flammability: – The ability to catch fire! (c) 2012 S. Coates

Chemical Properties Oxidation – The ability to react with Oxygen (c) 2012 S. Coates

Chemical Properties Toxicity – The ability to be poisonous (c) 2012 S. Coates

Chemical Properties Sensitivity to Light – The ability to change when exposed to light (c) 2012 S. Coates

Chemical Properties Reactivity with water – Some elements react explosively with water! – Sodium, Potassium, Lithium, and Calcium (c) 2012 S. Coates

Chemical Properties (c) 2012 S. Coates Video: Group I and II Metals Reacting with Water

Chemical Prop. And Changes Chemical Properties lead the way to chemical changes. These changes make NEW substances that have new structures… C CO H 2 O CO 2 Propane has a chemical property of flammability. When propane is burned these new substances are formed: C3H8C3H8 (c) 2012 S. Coates

Chemical Changes The letters are the same, but we’ve rearranged the structure and made new words! This is what happens in a chemical change! (c) 2012 S. Coates

Chemical Changes Indicators that a Chemical Change has occurred: –Fire –Light, Sound, Heat –Producing a gas (Fizz/Bubble) –Unexpected color change (c) 2012 S. Coates

Class Demonstrations As you watch each demonstration: – Determine if a physical change or a chemical change is taking place, – Watch for indicators that help you determine what kind of change is happening (c) 2012 S. Coates

Properties and Changes Let’s Summarize: All matter has physical properties and chemical properties. Physical properties can change, but the structure of the matter does NOT change Chemical properties lead the way to chemical changes. Chemical changes make new substances. (c) 2012 S. Coates