# Unit 2: Properties & Changes of Matter.  List 2 qualitative and 2 quantitative observations about this picture.

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Unit 2: Properties & Changes of Matter

 Identify the states of matter  Compare the physical and chemical properties of matter  Differentiate between mass and weight  Describe how matter is measured to calculate mass, volume and density

 Matter is anything that has mass and takes up space.  The 4 states of matter are: ▪ Solid ▪ Liquid ▪ Gas ▪ Plasma

Type of Matter Shape & volumeHow are Atoms moving? Attractive force between atoms SolidDefinite shape and volumevibratingStrong – holding them together LiquidDefinite volume but no definite shape Sliding past each otherWeaker force than solids GasNo definite shape and volume Atoms moving fast and free Very weak attractive force Plasma (Not in book) No definite shape or volume Atoms moving fast and free with an electrical charge Very weak attractive force

1. What do you do to change a solid to a liquid? 2. What do you do to change a gas to a solid? 3. In which state of matter are the particles always moving?

1. What do you do to change a solid to a liquid? You add energy 2. What do you do to change a gas to a solid? You take energy away 3. In which state of matter are the particles always moving? ALL OF THEM

1. Mass and Weight: ▪ Mass- amount of matter in an object ▪ Weight –mass X the gravitational pull on an object 2. Volume: the amount of space an object takes up L x w x h = cm 3 OR Displacement- Used to measure the volume of irregular shaped objects OR For Liquids

3. Density: the amount of matter in an object divided by the volume. D = m/v ▪ Density of water = 1g/cm 3  If density of a substance is less than 1, it will float  If density of a substance is greater than 1, it will sink ▪ Temperature affects density:  Temp. increases; density decrease  Temp. decreases; density increases ▪ Salinity affects density:  Salinity increases; density increases  Salinity decreases; density decreases

1. How do you measure the volume of a rectangular object? 2. How do you measure the mass of an object? 3. Why is our weight different on the Moon than here on Earth?

1. How do you measure the volume of a rectangular object? Length X width X height 2. How do you measure the mass of an object? using a balance scale and measured in grams 1. Why is our weight different on the Moon than here on Earth? Weight is dependent on the gravitational pull and the Moon has less gravity so we have less weight on the Moon.

4. Conductivity: the ability of an object or substance to conduct electricity. 5. Boiling Point: the temperature at which the liquid changes to gas (Water = 100 degrees Celsius or 212 degrees Fahrenheit) 6. Melting Point: the temperature at which a solid becomes a liquid (Water = 0 degrees Celsius or 32 degrees Fahrenheit)

7. Solubility: the ability of an object to dissolve in another ▪ Solute- the substance being dissolved ▪ Solvent- the substance in which the solute is being dissolved in.  Water is considered a universal solvent. 8. Magnetism: the ability of an object to attract a magnetic force

1. In the ocean, water is the _____________ and salt is the _____________. 2. The ability of an object to dissolve in another substance is called _____________________. 3. The temperature shown when a liquid changes to a gas is called the ________________.

1. In the ocean water is the _solvent_ and salt (Sodium Na) is the _solute____. 2. The physical property of matter that ability of an object to dissolve in another substance is _solubility____. 3. The physical property of matter that is when a liquid changes to a gas is __boiling point____.

 Density and Melting Point are good properties for identifying unknown substances because they do not depend on the size of the sample( the amount of the material).

Chemical property: the ability or inability of a substance to combine with or change into one or more new substances  Examples:  Flammability: the ability of a type of substance to burn easily.  Most flammable = Hydrogen (H) gas  Reactivity : the ability of a type of substance to react with another substance.  Most likely to Rust (react with oxygen) = Metals with Iron (Fe)

 What happens to the density of an object when you cut it in half?  Give a situation where you would need to know whether a substance or object is reactive or flammable.

 Identify the types of changes of matter – physical and chemical  Compare the signs of physical and chemical changes of matter  Describe how mass is conserved when a chemical reaction occurs (Law of Conservation of Mass)

 A change in the size, shape, form, or state of matter that does NOT change the matter’s identity is called a physical change.  Examples:  melting ice  ripping paper  cutting wood  erosion of a boulder

 Because the chemical properties of the substances in dissolving and changing and change of state stays the same, they are considered to be physical changes.

 A chemical change is a change in matter in which the substances that make up the matter change into another substance with different chemical properties

Formation of Gas Explosion Formation of precipitate Odor change Color change

 The Law of Conservation of Energy : energy cannot be created or destroyed, but it can be transformed  Some chemical changes release thermal, light, and sound energy. (Exothermic Reactions)  ex: Burning  Some chemical changes need thermal energy for them to occur. (Endothermic Reactions)  ex: photosynthesis

 Law states that the total mass before a chemical reaction is the same as the total mass after the chemical reaction.