2.  Make-up quiz on Friday for everyone.  Office hours Thursday afterschool.  If you have questions, COME SEE ME.

3.  Workbook pages 1-19  All pages up to page 19 should be completed in your workbook by now.  Page 27 questions 1-3

4.  Any change that alters the form or appearance of matter but does not make any substance in the matter into a different substance.  A substance that undergoes physical change is still the same substance after the change

5.  We know that matter has three states:  Solid  Liquid  Gas  What are some examples of each?

6.  Let’s say you left a puddle of water on the kitchen table. A few hours go by, you come back, and the puddle is gone.  Did the water disappear?  No, a PHYSICAL CHANGE occurred. The liquid water changed into water vapor (a gas) and mixed with the air  A change in state (from solid to liquid or gas) is a physical change

7.  Is there a physical change when you dissolve sugar or salt in water?  To be sure, you need to make sure that the salt or sugar hasn’t changed into a new substance.  For example, we know that sugar is sweet. A sugar solution is as sweet as the undissolved sugar. It’s still SUGAR.

8.  Physical changes include:  Dissolving  Bending  Crushing  Breaking  Chopping  Filtration  distillation

9.  A change in matter that produces one or more new substances is a chemical change (or chemical reaction).  A single substance changes to one or more other substances

10.  One example is when hydrogen peroxide is poured on a cut on your skin, it breaks down into water and oxygen gas.  When natural gas burns on a stove (methane), it combines with oxygen in the air and forms new substances- carbon dioxide and water vapor

11. Chemical ChangeDescriptionExample CombustionRapid combination of fuel with oxygen; produces heat, light, and new substances Gas, oil, or coal burning in a furnace ElectrolysisUse of electricity to break a compound into elements or simpler compounds Breaking down water into hydrogen and oxygen OxidationSlow combination of a substance with oxygen Rusting of an iron fence TarnishingSlow combination of a bright metal with sulfur, producing a dark coating on the metal Tarnishing of brass

12. Vanessa Turchan

16.  One example of a physical change is:  A)burning paper  B)baking cookies  C)heating table sugar  D)dissolving salt in water

17.  The answer is D- dissolving salt in water  One example of a chemical change is:  A) filtering  B)burning wood  C)boiling water  D)crushing a can

18.  The answer is B- burning wood

19.  Law of conservation of mass: matter is not created nor destroyed in any chemical or physical change  Since mass measures matter, this can also be called the conservation of matter

20.  Let’s look at the example on page 25 of methane gas burning.  For every molecule of methane that burns, 2 molecules of oxygen are used. The atoms re-arrange, but do not disappear during the reaction.

21.  Energy: the ability to do work or cause change  Every chemical or physical change in matter includes a change in energy

22.  Temperature: a measure of the average energy of random motion of particles of matter.  Warmer particles have greater average motion than cooler particles.

23.  When matter changes, the most common form of energy released or absorbed is thermal energy  For example, ice absorbs thermal energy from its surroundings and melts.  The melting of ice is an ENDOTHERMIC change

24.  Endothermic: a change in which energy is taken in, or absorbed.  Exothermic: releases energy.  Combustion is an example of exothermic change because it releases energy in the form of heat.

25.  When you see fireworks in the sky, what kind of thermal energy are you seeing?  When ice melts, is thermal energy released or absorbed?

26.  Fireworks give off energy in the form of heat and light, so it’s an exothermic change.  Ice melts because it absorbs heat from the environment, making this an endothermic change.