Chemistry Mrs. Algier Do Now: Explain the difference between a heterogeneous and homogeneous mixture. Give 2 examples of each.

YWBAT Differentiate between elements and compounds Distinguish between a substance and a mixture. Describe what chemists use to represent elements and compounds.

Matter Classification Matter Mixture Substance Heterogeneous HomogeneousElementCompound

Elements Element – simplest form of matter that has a unique set of properties. Examples – Oxygen – Hydrogen – Carbon

Compounds Compound – a substance that contains 2 or more elements chemically combined in a fixed proportion. – The properties of compounds are quite different from those of their component elements Examples – Oxygen, hydrogen, and carbon chemically combine to form sucrose, C 12 H 22 O 11 – Water, H 2 O

Meet the Elements 6U

Elements vs. Compounds Compounds can be broken down into simpler substances by chemical means, but elements cannot.

Chemical Change Chemical Change – a change that produces matter with a different composition than the original matter Examples – Heat – Electrical current

Substances Elements - Substances that CAN NOT be broken down by any physical or chemical method. Examples: Gold Oxygen Mercury Compounds Substances that CAN be broken down in to different elements using chemical methods Examples: Water (H 2 O) Carbon Dioxide(CO 2 )

Matter Classification Matter Mixture Substance Heterogeneous HomogeneousElementCompound

Mixture or Substance? If the composition is fixed, the material is a substance. If the composition varies, the material is a mixture. – Is there more than one version? If the answer is yes, then it is a mixture. Milk (skim, 2%, whole) Gasoline (different octanes)

Chemical Symbols Used by chemists to represent elements People everywhere in the world use the same chemical symbols First letter is always capitalized. Second letter is not capitalized. Examples: – Au – Hg

Chemical Symbols

Chemical Formulas Used by chemists to represent compounds. – Subscripts tell you how many of each type of element are in the compound. Examples: – Table Sugar: C 12 H 22 O 11 – Water: H 2 O

Periodic Table Periodic Table – Used by chemists to group elements based on properties – Each element is identified by its symbol placed in a square. – Elements are listed in order from left to right and top to bottom by atomic number. – The atomic number is shown centered above the symbol. – Period – horizontal row – Group – vertical column

Periodic Table

YWBAT - Review Differentiate between elements and compounds Distinguish between a substance and a mixture. Describe what chemists use to represent elements and compounds.