1. Evidence of Chemical Changes How can you tell something has changed into something new?

2. Evidence we already know: A gas is produced ▫Evidence: you will see bubbles or hear fizzing The temperature changed ▫What you are working with got hot or cold  Endothermic = feels colder  Exothermic = feels hotter Color change ▫Think of the Statue of Liberty – it WAS copper, now it’s a green color….that’s a chemical change!

3. More evidence! It smells different ▫If something has a different odor than before, a chemical change has happened It changes form ▫If you burn something, like paper Light, heat, or sound is given off ▫When something explodes If a solid forms ▫Science Fancy Word: solid forms = precipitate

4. If we could see the atoms… Which part of the atom is responsible for reactivity? Hint: it’s the outermost something… Those interact with each other to form something new. The Main Point!

5. So what is a physical change? Physical Change: you do not make a new substance Physical Change examples: ▫Changes states of matter (solid, liquid, gas)  Example: Water, Ice, and Steam are all the same – you have just changed the physical properties  Example: making a baseball bat out of wood – the wood has only changed shape

6. Let’s get some practice! In the next few slides, use your ring cards to select either: A)Physical Change B)Chemical Change C)Don’t Know Be prepared to explain why it’s the type of change it is! You can use your notes from today if you need to.

7. Which type of change? http://whatscookingamerica.net/Foto4/BoilingWater.bmp

8. Which type of change? http://www.google.com/imgres?q=ripping+paper&hl=en&gbv=2&tbm=isch&tbnid=thafyuekIpHt6M:&imgrefurl=http://www.bairarteditions.com/ripper/&docid=0Yf_4cf2jAxknM&w=576&h=317&ei=pblyTvWRM5TJsQL46pDaCQ& zoom=1&iact=hc&vpx=675&vpy=190&dur=889&hovh=166&hovw=303&tx=211&ty=69&page=1&tbnh=94&tbnw=171&start=0&ndsp=15&ved=1t:429,r:4,s:0&biw=1024&bih=630

9. Which type of change? Digesting Food http://www.google.com/imgres?q=digesting+food&hl=en&gbv=2&tbm=isch&tbnid=3w1uFRwVZsXKyM:&imgrefurl=http://byhealth.com/digestive-system&docid=EsLSOzq6M__IvM&w=699&h=837&ei=-7lyTtvvCO7LsQK- 0bCZCw&zoom=1&biw=1024&bih=630&iact=rc&dur=265&page=1&tbnh=109&tbnw=91&start=0&ndsp=17&ved=1t:429,r:4,s:0&tx=69&ty=39

10. Which type of change? Flammability http://www.google.com/imgres?q=flammability&hl=en&gbv=2&tbm=isch&tbnid=REMWMZsxrWRlJM:&imgrefurl=http://www.sgs-cqe.de/en/flammability-test-for-plastic-materials-/- components.html&docid=ZGVnk1mVtYju6M&w=275&h=199&ei=srpyTqWoBcKAsgLPspi_CQ&zoom=1&iact=hc&vpx=468&vpy=131&dur=1856&hovh=159&hovw=220&tx=133&ty=102&page=1&tbnh=123&tbnw=162&start=0&ndsp=15&ved=1t:429,r: 7,s:0&biw=1024&bih=630

11. Which type of change? http://custom.buyitsellit.com/29169/images/staedlter/pencils/158_sharpening.jpg