Physical and Chemical Properties and Changes

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

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

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

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

Physical Changes Do NOT CHANGE THE TYPE OF MATTER –Nothing new or different is formed Could be a change in: –Size, Change in state, Color, Shape

Examples of Physical Changes Boiling, Freezing, Dissolving, Breaking Making a mixture 2 or more types of matter (substances) mixed together –Not in specific amounts – Can be separated physically

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 a chemical reaction –Formation of gas –Formation of precipitate –Change in color –Change in energy

Types of Reactions Endothermic Absorbs heat energy (The substance gets warm, while the environment gets cold) Exothermic Releases heat energy (The substance gets cooler, while the environment gets warmer)

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