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What is chemistry?

What is chemistry?

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What is chemistry?

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  1. What is chemistry?

  2. Chemicals • Chemicals = “stuff” of the world • Anything that has substance or is made up of matter is a chemical. • Natural chemicals • Synthetic chemicals • Chemistry studies the properties, changes, and interactions of chemicals. • Chemistry does not study the esoteric- • For example, what makes up an idea? The soul? Love?

  3. Physical Characteristics of matter • Three Newtonian states of matter- • Solid (s): constant volume and shape, least molecular movement. • Liquid (l): constant volume, variable shape. • Gas (g): variable volume and shape, highest molecular movement. • There are other states of matter that will not be studied at this level, i.e. plasma (state of stars). • Non-Newtonian states of matter- • There are states of matter that fall between the Newtonian states.

  4. Quick Lab-Non-Newtonian State • You will find a small beaker containing sodium bicarbonate (s) and a small beaker containing water (l) at your desk. • Take a small amount (1-2 tablespoons) of the powder into the palm of one hand. • Add water to the powder in your hand until a paste-like consistency is achieved. • Hold your hand still-what state describes your mixture? • Squeeze the mixture-what state does your mixture resemble now? • Write 2-5 sentences in your notes that describe what you did (procedure), what you saw (data), and what you concluded. (This is a lab grade).

  5. Physical properties of matter • Physical properties of matter describe a characteristic of the matter that can change, without changing the chemical itself. • State • Size • Temperature • Mass • Volume

  6. Physical changes of matter • A change in a physical property results in a physical change-this is not a reaction. • Example: an ice cube melting-the state of the water changes from solid to liquid, however, the water is still water. • Homework question 1: give a specific example of a physical change for each of the following physical properties: state, size, shape, temperature, mass, volume. Remember, the chemical make-up of the matter must remain constant!

  7. Chemical properties of matter • Chemical properties of matter are the characteristics that describe the fundamental nature of the substance. • Chemical structure • Ratio of elements • Density • Melting point • Boiling point • Fluorescence • Luminescence • Some observable chemical characteristics can be tricky- • Color- colors can be a fundamental characteristic, however, colors can fade for purely physical reasons. • Scent-scents are by definition a chemical property, however the human nose is not the most reliable instrument and describing a scent is very subjective.

  8. Chemical changes of matter • A chemical reaction (rxn) or chemical change is any fundamental change in a chemical’s make-up. • A rxn results in the rearrangement of atoms from one chemical into a new chemical. • A rxn starts with a reactant/reactants (rct) and ends in new product/products (pdt). • Chemical reactions are written in a scientific shorthand: Rct  Pdt

  9. Quick lab-chemical reactions • I will start with a piece of paper (reactant). • Describe the characteristics of the paper (both physical and chemical). • Watch the reaction occur. • Record your observations. • Describe the characteristics of the product(s). • What did you observe that leads you to believe this was a chemical reaction? Homework Question 2: write down three observations (other then what you saw here) that may indicate a chemical reaction has occurred, and why you believe these observations indicate a chemical reaction.

  10. Examples of chemical reactions http://www.youtube.com/watch?v=qQGYK-j_PuY

  11. Homework: • In addition to the two quick lab write-ups (which will be checked in your notebook by the end of the hour!) and the two homework questions in the notes, you must complete the following research question: • Look at the products in your bathroom at home (shampoo, lotion, cleanser, toner, etc.) • Choose a product with at least seven ingredients; record the brand and product name and the ingredients (in order) listed on the packaging. • Use the internet to find the chemical formula for the third, fifth, and seventh chemical listed. • Don’t forget to cite your sources!!! • Due tomorrow!