Chapter 2 Classifying Matter

Classifying Matter Elements- cannot be broken down into simpler substances and still retain all of it’s properties Elements- cannot be broken down into simpler substances and still retain all of it’s properties  Represented by symbols on the periodic table  Examples: P, S, or Fe

Classifying Matter Compounds- made of two or more pure substances and can be broken down Compounds- made of two or more pure substances and can be broken down  Properties of the elements change when they join together  Example: H 2 0

Mixtures Heterogeneous- parts of the mixture are noticeably different Heterogeneous- parts of the mixture are noticeably different –Example: Sand, chocolate chip cookie  These are also called suspensions when they separate from one another. These are substances you must shake before using. –Example: Salad dressing

Heterogeneous Mixtures

Mixtures Homogeneous- “same”; not able to distinguish the individual components Homogeneous- “same”; not able to distinguish the individual components  These are also called solutions –Ex: swimming pool

Homogeneous Mixtures

Solutions Solutions have 2 parts: A. Solute- what you are adding to be dissolved; the part that is being dissolved B. Solvent- what is being used to dissolve something else. Water is the “universal solvent” Example: Swimming pool, Kool-aid

Colloid- contains medium sized particles that scatter light Colloid- contains medium sized particles that scatter light –Example: Fog, milk

Summarizing Matter Element Mixture

Material Pure Substance or Mixture Element, Compound, Homogeneous, Heterogeneous Concrete Sugar + pure water (C 12 H 22 O 11 + H 2 O) Limestone (CaCO 3 ) Orange juice w/ pulp Pacific Ocean Aluminum (Al) Tap water in glass Chex mix Muddy water Baking soda (NaHCO 3 )

Physical Properties and Physical Change Physical Property- can be observed without changing the composition Physical Property- can be observed without changing the composition

A. Viscosity- resistance to flow A. Viscosity- resistance to flow 1. The HIGHER the viscosity the THICKER the substance. Ex: Honey 2. The LOWER the viscosity the THINNER the substance. Ex: water

B. Conductivity- material’s ability to allow heat to flow B. Conductivity- material’s ability to allow heat to flow 1. Conductors- metals 2. Insulators- wood, plastic

C. Malleability- ability for a substance to be hammered into sheets without shattering C. Malleability- ability for a substance to be hammered into sheets without shattering –Ex: gold

D. Hardness- if the substance will scratch another substance D. Hardness- if the substance will scratch another substance –Ex: diamond

E. Melting and Boiling points E. Melting and Boiling points –1. Melting- Solid to liquid –2. Boiling- Liquid to gas

F. Density- used to test the purity of a substance F. Density- used to test the purity of a substance –1. If the object is less dense than the liquid it is in it will float and it the object is more dense it will sink  Ex: soap or rock in water

Using Physical Properties A. Filtration- separates materials based on their size A. Filtration- separates materials based on their size B. Distillation- separates substances in a solution based on their boiling points B. Distillation- separates substances in a solution based on their boiling points

Physical Change- occurs when properties of a substance change but the composition does not. Physical Change- occurs when properties of a substance change but the composition does not. –Ex: crumpling paper, slicing tomatoes, freezing water

Chemical Properties and Chemical Change Chemical Property- ability to produce change in the composition of matter Chemical Property- ability to produce change in the composition of matter A. Flammability- ability to burn in the presence of oxygen B. Reactivity- how readily a substance combines chemically with other substances

Chemical Change- occurs when a substance reacts and forms one or more new substances Chemical Change- occurs when a substance reacts and forms one or more new substances –Ex: baking a cake, leaves changing color, digestion of food

Indicators of Chemical Change A. Change in color because of chemicals A. Change in color because of chemicals B. Production of a gas (burning) B. Production of a gas (burning) C. Formation of a precipitate (liquid to a solid) C. Formation of a precipitate (liquid to a solid)

Chemical vs. Physical A. If DIFFERENT substance are present after the change it is CHEMICAL, if not then it is a PHYSICAL change A. If DIFFERENT substance are present after the change it is CHEMICAL, if not then it is a PHYSICAL change

Quiz 3 1. What is a homogenous mixture? Give 1 example. 2. What is a colloid? 3. What is a physical property? Give 2 examples. 4. Give 2 examples of one physical change. 5. Salt (NaCl) is a (compound/element). 6. Soil from a garden is a (homogeneous/heterogeneous) mixture.