Under the document camera October 24, 2015 Day 2 1. Please have these Items on your desk. Science Starters Sheet Agenda Science Starter: Under the document camera

Table of Contents Update . . . . . Page 43-44 10/24 Physical/Chemical Changes & Properties

Physical versus Chemical Properties

Reviewing MATTER Matter: anything that has mass and takes up space Mass – the amount of matter in something Volume – the amount of space something occupies Which of the following is matter? A car? A box? You?

What is a property? Property: a characteristic of a substance that can be observed

Matter can be changed two ways Physically Physical reaction Physical change Chemically Chemical reaction Chemical change

Physical Property Physical property: a property that can be observed without changing the identity of the substance. Examples: luster malleability: the ability to be hammered into a thin sheet ductility: the ability to be stretched into a wire melting point boiling point density solubility specific heat

Special Physical Properties Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure water = 100oC

Physical Changes Do NOT CHANGE THE TYPE OF MATTER Nothing new or different is formed Could be a change in: A. Size B. Change in state C. Color D. Shape

Examples of Physical Changes A. Boiling B. Freezing C. Dissolving D. Breaking E. Making a mixture 2 or more types of matter (substances) mixed together Not in specific amounts Can be separated physically

Chemical Properties Chemical property: a property that can only be observed by changing the identity of the substance Examples: flammability ability to rust reactivity with vinegar

Picture from www.chem4kids.com Chemical Changes The composition of the substance changes. The substances present at the beginning of the change are not present at the end; new substances are formed. The change cannot be “undone.” Picture from www.chem4kids.com

Evidence of Chemical Reactions Chemical Reaction: The process by which the atoms of one or more substances are rearranged to form different substances. Temperature change Color change Gas or solid appears

https://www.youtube.com/watch?v=X328AWaJXvI Bozeman video clip

4. An energy change (Temperature) Endothermic reaction-a chemical reaction accompanied by the absorption of heat. Exothermic reaction-a chemical reaction that releases energy. The energy “ex”its. It is the opposite of an endothermic reaction. https://www.youtube.com/watch?v=L-G7pLufXAo

Example of everyday endothermic reactions https://www.youtube.com/watch?v=7q04F-juT-c

Examples of everyday exothermic reactions

Chemical Changes Atoms are re-arranged, NOT created or destroyed

Law of Conservation of Matter Matter is conserved  type of atoms does not change Nothing is created or destroyed

Change of Matter::::Physical change: Identity Retained. This type involves a change in the observable properties of matter without a change of the substance identity.  In most physical change of matter, no bonds are broken between atoms and the identity of the substance is retained. Example:  Phase Change  
In a phase change matter changes from solid, liquid or solid but the identity of the substance is retained. 
 

Change of Matter:::::Chemical change: Identity Changed 
This type of change refers to a material changing to a completely different type of material or transformation to a new substance. This process involves bond breaking and bond forming such that material changes identity. 
  Example:  Decomposition of water. In the decomposition of water, water molecules H2O are broken down to hydrogen and oxygen.

Consider the following examples, which of these are phyiscal and which are chemical change Heating sugar vs. adding sugar to water Cutting wood vs. burning wood. 3. The electrolysis of water vs. ice melting.

Answers. . . . . . . .. Physical Change Chemical Change 1. Sugar dissolving Sugar heating 2. Cutting Wood Burning Wood 3. Melting Ice Electrolysis of water