Unit 2 Matter and the Changes They Undergo

Phases of Matter  The type and arrangement of the particles in a sample of matter determine the properties of the matter  Three states of matter: 1. Solid 2. Liquid 3. Gas

Solids  Definite shape, size, and volume  Molecules are closely packed together  Molecules are vibrating

Liquids  No definite shape or size, but DOES have a definite volume  Molecules are loosely packed together  Molecules are sliding and bouncing off of one another

Gases  No definite shape, size, or volume  Molecules are separated by great distances  Molecules are traveling in a straight line of motion until they hit something

Matter  Matter – Anything that takes up spacethat you can think of?  Matter has Physical and Chemical properties

Physical Properties  Physical Properties are properties that describe the look or feel of a substance  Example : color, hardness, density, texture, phase  Every substance has its own unique physical properties that can be used to identify the substance.

Physical Properties  These properties can change when conditions change  However, are still unique (do not change into another substance)  Water to ice is a physical change (same chemical composition)

Chemical Reactions  Propane Chemically Reacts with oxygen to yield water and carbon dioxide  Propane and oxygen gas are the REACTANTS and water and carbon dioxide are the PRODUCTS

Chemical Properties  Chemical Properties – The ability of a substance to react with other substances or to transform from one substance to another

Chemical Properties Altering a Chemical Property :  Changes the way the atoms in the molecules are chemically bonded to one another. This is known as a Chemical Change.  Chemical Change means the materials are Reacting  What do we call this process of materials Reacting Chemically?

Chemical Reactions  In a Chemical Reaction, new materials are formed by a change in the way the atoms are bonded together  Atoms actually rearrange within the molecules  UNLIKE A PHYSICAL CHANGE WHICH KEEPS THE ORIGINAL CHEMICAL COMPOSITION

Evidence of a Chemical Change / Reaction  Bubbles: Formation of a gas  Solid/Precipitate is formed  Release or absorption of energy (gets hot or cold)  A color changed in the system

Physical or Chemical Change? SO… What is a Physical Change ??? What is a Chemical Change ???

Check: Physical or Chemical Change?  Characterize the following scenarios as physical or chemical changes:  Water to ice  Car: Iron to Rust  Crushing up a stone to a fine powder  Photosynthesis  Cutting grass  Propane burns in a grill

Matter (Review)  What is Matter?  Anything that has mass and volume (anything that takes up space)  Mass??  Volume??

Space an Object Occupies  The Space an Object Occupies is the object’s volume  Volume can be measure by LxWxH if a square or rectangle  mL, L, cm 3  But, how about an odd shaped solid??  Even better, how about a gas or liquid??

Quantity of Matter  The Quantity of Matter is the Mass  A marble is smaller than a ping pong ball but has more mass  It contains more MATTER  Mass can be measured using a balance  g, kg

Mass is NOT Weight  Mass is a measure of the amount of matter an object contains  Weight, on the other hand, is defined as the force produced by gravity acting on a mass  Mass is the same on the moon, whereas weight will change

Units of Measurement  Heavy, light, rough, smooth are qualitative measurements  Mass and volume can be described in number values  quantitative measurements  Volume is the Quantity measured in milliliters (the Units )

Système Internationale d’Unités (SI units)  Scientists use the SI (Metric) system for ALL measurements  English (American) System is not accepted  The SI System is built on the seven bas units listed below

QuantitySymbolUnitAbbreviation LengthlMeterm MassmKilogramkg TimetSeconds TemperatureTKelvinK Amount of Substance nMolemol Electric CurrentIAmpereA Luminous IntensityIvIv Candelacd

Elements Quiz #2 #1-38 and on Thursday