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Mr. Taglia Intro Unit
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The official definition of Chemistry is listed as: “The study of matter and the changes it undergoes…”
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Matter is anything that has mass and takes up space. Mass is a measurement that reflects the amount of matter. (usually measured in grams) Volume is the amount of space matter takes up. (usually measured in Liters or milliliters)
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All different forms of matter possess a set of chemical and physical properties Physical- what we can observe with our senses alone… Chemical- how a type of matter might chemically interact with other types
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Matter can change its structure and its composition Changes in the structure and composition of matter lead to changes in the properties of the matter. Two types of changes are: Chemical Changes – changes in composition Physical Changes – changes in form
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Color change Temperature Presence of a new material Bubbles/Fizz Physical characteristics and changes Odor
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Mass is neither created nor destroyed during a chemical reaction…. ***~Law of Conservation of Mass~*** So where does it go if the starting and ending masses are different?
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The scientific method is a systematic approach used in scientific study (chemistry, physics, biology, etc…)
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Observation Scientific study begins with an observation. It is simply the act of gathering information ▪ Qualitative information - color, odor, shape, and other physical characteristics ▪ Quantitative data - numerical information (temperature, pressure, volume, quantity, etc..)
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Create a Hypothesis A Hypothesis is a tentative explanation for what has been observed.
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Conduct an experiment to test the hypothesis… ▪ Independent variable - the variable that you plan to change and control ▪ Dependent variable - the variable whose value changes in response to a change in the independent variable (Usually a measurement) Record Data & Observations…
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Draw a Conclusion A conclusion is a judgment based on the information Go back to your hypothesis and see if you were right.
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Theory A theory is an explanation that has been supported by many, many experiments
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Scientific Law - a relationship in nature that is supported by many experiments.
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Fundamental units (also called base units) Length = meter (m) Mass = kilogram (kg) Time = seconds (s) Temperature = degrees Kelvin (K) Number of particles = moles (mol)
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Derived units - are combinations of fundamental units Density - a ratio that compares the mass of an object to its volume. Units are often grams per milliliter (g/mL)
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Reference Tables Table T (first equation) If a sample of wood has a mass of 125 g and a volume of 132 mL, what is its density? Solution Density = mass / volume =125 g / 132 cm 3 = 0.947 g/cm 3
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Accuracy is the extent to which a measured value agrees with the standard or accepted value. Accuracy is measured using percent error % error = [(measured value - accepted value) / accepted value] x 100 Reference Tables Table T
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Precision is the degree of exactness (if that’s a word) to which the measurement of a quantity can be reproduced Precision is linked to significant figures Significant figures includes all known digits
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Numbers expressed as ? x 10 ?
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Express 0.0000578 in scientific notation. Express 2900 in scientific notation. In your calculator, type in the number 4.567x10 8.
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Use your calculator to perform the following calculation (3.45x10 12 kg) x (4.3x10 -2 m/s 2 ) Express your answer with the correct units.
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Going from degrees Celsius to Kelvin. Use the formula on Table T : K = °C + 273 Try These Conversions: a) 30°C to Kelvin… b) 180 K to Celsisus…
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