Presentation on theme: "Chapter 1: The Nature of Science. What is Science? Life, Earth and Physical Science Living things Earth and Space Matter and Energy Chemistry Physics."— Presentation transcript:
What is Science? Life, Earth and Physical Science Living things Earth and Space Matter and Energy Chemistry Physics
Steps to the Scientific Method Observation a question Gather Info Hypothesis – a tentative answer Experiment – test the hypothesis Conclusion If doesn’t work Observation a question Gather Info Hypothesis – a tentative answer Experiment – test the hypothesis Conclusion
Variables and Constants Variable - Things that are changing Constants – Things that are NOT changing Control – A test that is left alone. Nothing is done in this test.
Conclusions Scientific law: describes how nature behaves. Normally is always true. Theory: explains why nature behaves in the way described by the law. Predicts results of further experiments.
Now… Let’s use this Method Observation a question Gather Info Hypothesis – a tentative answer Experiment – test the hypothesis Conclusion
What’s in Frankenstein’s Head?? 1. Read the handout 2. Record your observations 3. Draw a diagram of your model 4. Have your final model approved 5. Answer final questions
Composition of Matter – Sec. 1 Pure Substances – Same composition throughout – Either an element or compound Element – All one type of atom – Everything made of atoms Compound – Atoms of two or more elements chemically bonded together
Composition of Matter Mixtures – Made of two or more substances that can be easily separated by physical means Heterogeneous Mixture – Different materials can be seen easily – Granite, concrete, vegetable soup Homogeneous Mixture (Solution) – Blended evenly throughout – Vinegar, Kool-aid
MATTER Can it be separated? Mixtures Substance Homogeneous Mixture Air, sugar water, stainless stell Heterogeneous Mixture Granite, wood, blood Compounds Water, sodium chloride Elements Gold, aluminum yes no
Mixtures Colloid ~ heterogeneous – Particles larger than solution but not heavy enough to settle out – Milk, paint, fog and smoke Detecting Colloids – Pass a beam of light through it Colloid – See beam Solution – Cannot see beam – Particles big enough to scatter light – Tyndall Effect
Mixtures Suspension ~ heterogeneous – Not solution, not colloid – Muddy pond water – Heterogeneous mixture with a liquid and visible particles that settle
Physical Properties Def: characteristic observed without changing the identity of the material – Ex: color, shape, size, density Appearance Behavior – Magnetic, malleable, flow of liquid
Separating Mixtures Sand and Rock mixture? – Filter or sift Iron filings and Aluminum mixture? – Magnet
Physical Change Change in size, shape or state of matter and identity is same – Solid to a liquid? – Yes
Solid Liquid Gas Melt Evaporate Condense Freeze
Physical Change How to get pure water from salt water? – Distillation – evaporate liquid and then recondense it
Chemical Properties and Changes Chemical Property – can be observed only by changing the substance – Flammability, reactivity, decomposition Chemical Change – change where a NEW substance is formed Weathering – Physical or Chemical Change? – Both!
Law of Conservation of Mass Matter is neither created nor destroyed during a chemical reaction Mass of all substances before = mass of all substances after change