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Monday, 9/25/17 Day 1. Science Warm Ups. Agenda. AR Book under desk. Science notebook. 1. Please have these Items on your desk. Fill out your Agenda. Science Starter: What is a physical characteristic? What is a chemical characteristic?. Physical versus Chemical Properties.
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Monday, 9/25/17 Day 1 ScienceWarm Ups Agenda ARBookunder desk Sciencenotebook 1. Please have these Items on your desk. Fill out your Agenda. Science Starter: • What is a physical characteristic? • What is a chemical characteristic?
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
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 • https://www.youtube.com/watch?v=znsPa1BSaIM
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 gas 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 ChangeChemical Change 1. Sugar dissolving Sugar heating 2. Cutting Wood Burning Wood 3. Melting Ice Electrolysis of water