October 20, 2015 Day 2 Science Starters Sheet 1. Please have these Items on your desk. Science Starter: Under the document camera Agenda

Table of Contents Update..... Page 51 10/19 Physical/Chemical Changes & Properties

Physical versus Chemical Properties

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? Reviewing MATTER

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

Matter can be changed two ways 1.Physically 1.Physical reaction 2.Physical change 2.Chemically 1.Chemical reaction 2.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 = 100 o C

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

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

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. L-G7pLufXAohttps:// L-G7pLufXAo

Example of everyday endothermic reactions juT-chttps:// 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. Change of Matter 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 subsstance 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 H 2 O are broken down to hydrogen and oxygen.

Consider the following examples, which of these are phyiscal and which are chemical change 1.Heating sugar vs. adding sugar to water 2.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