CHAPTER 2 Matter and Change

What is Matter?  Matter is anything that has mass and takes up space  Mass = the amount of matter an object contains  Space = volume

Classification of Matter 1. Pure Substance = contains only one kind of matter; chemical composition is uniform 2. Mixture = a physical blend of two or more substances; chemical composition can vary

Classification of Matter I. Pure Substance A. Element (think periodic table) B. Compound (chemical combination of elements)

Classification of Matter II. Mixture A. Homogenous (uniform composition) 1. Solution 2. EX: salt water B. Heterogenous (not uniform in composition) 1. EX: tossed salad

 Homogeneous mixtures (uniform in composition)  Also known as solutions  Very important in chemistry  May be any combination of solids, liquids or gases  Carbon dioxide and oxygen (air) gas-gas  Water vapor in air (moist air) liquid-gas  Carbon dioxide in water (soda water) gas-liquid  Acetic acid in water (vinegar) liquid-liquid  Sodium chloride in water (salt water) solid-liquid  Copper in silver (sterling silver) solid-solid Classification of Matter…mixtures READ ONLY

 Heterogeneous mixtures (not uniform in composition) Classification of Matter…mixtures

Classifying matter activity

Progress Check  Substance or mixture??? 1. Lemonade 2. Pure water 3. CO 2 4. dirt

Mixtures can be separated by physical methods 1. Filtration (heterogeneous mixtures)  Components separated based on size 2. Distillation (homogenous mixtures)  A solution is boiled to produce a vapor that is then condensed again to a liquid 3. Chromatography  A solution is separated as it passes over a solid

Mixture Separation Challenge  How would you separate…  Red m&m’s from green m&m’s  Salt from salt water  Iron from a mixture of iron and sand  Salt from sand  Salt from pepper

Mixture Separation Lab  Mixture of salt, sand, iron, sulfur…how would you separate the mixture into its individual components?  Think physical properties of each…

States of Matter

Do this…  Describe shaving cream to someone else sitting at your table.

States of Matter 1. Solid  Shape: Definite  Volume: Definite  Compressibility: None  Particle Spacing: close together  Particle Movement: very little (low energy)

States of Matter 2. Liquid  Shape: Indefinite  Volume: Definite  Compressibility: slight  Particle Spacing: not as close as a solid  Particle movement: more movement that solid

States of Matter 3. Gas  Shape: Indefinite  Volume: Indefinite  Compressibility: Great  Particle Spacing: far apart  Particle Movement: Fast (lot of energy)

Is a gas the same thing as a vapor?  Gas = a substance that exists as a gas at room temperature  Ex: air is a mixture of gases including oxygen and nitrogen gas  Vapor = gaseous state of substance that is normally a solid or liquid at room temperature  Ex: steam = gaseous form of water  Ex: moist air contains water vapor

What states of matter can you find in shaving cream?  Shaving cream is a colloid, a heterogenous mixture of a liquid and gas State Debate

Describing Matter

Physical Properties  Qualities of matter that can be observed or measured without changing the substance’s composition  Include color, solubility, odor, hardness, density, melting point and boiling point  Help chemists identify substances

Using physical properties to identify an unknown…  Two clear liquids  Liquid A boils at 100 o C and melts at 0 o C  Liquid B boils at 78 o C and melts at -117 o C A B READ ONLY

Physical Change  Change in matter without a change in the chemical composition  Ex: boil, freeze, dissolve, melt, condense, break, split, crack, grind, crush…

Chemical Properties  The ability of a substance to undergo a chemical reaction and to form new substances is called a chemical property  Chemical properties are only observed when a substance undergoes a chemical change

Chemical Changes  Occur during a chemical reaction  One or more substances combine to form new and different substances  EX: rusting, decomposing, rotting, spoiling, exploding, corroding, burning,

How to tell whether a chemical reaction has taken place?  Energy is always absorbed or given off in a chemical reaction  Energy change by itself does not indicate chemical change  Change in color  Change in odor  Production of a gas  NEW SUBSTANCE FORMED

Things to Know for QUIZ tomorrow  VOCABULARY  Branches of chemistry  Steps of the scientific method  Classifying matter (element, compound, mixture; heterogenous, homogeneous)  Characteristics of the states of matter (solid, liquid, gas)  Physical properties  Physical change vs chemical change  Evidence of a chemical change

EOC Questions  CHAPTER 1  Page 25 # 16, 18, 30, 31  CHAPTER 2  Page # 24, 25, 28, 30, 32-36, 44, 48