Chem 1, week 1 notes
Chem 1, week 1 notes CH-1213-32
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This 6 page Class Notes was uploaded by Victoria Mazur on Saturday August 20, 2016. The Class Notes belongs to CH-1213-32 at Mississippi State University taught by Dr. Dornshuld in Fall 2016. Since its upload, it has received 361 views. For similar materials see Chem 1 in Chemistry at Mississippi State University.
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Date Created: 08/20/16
Definitions Chemistry- the study of the composition, properties, and interactions of matter; the “central science” Matter- anything that occupies space and has mass Mass- a measure of the amount of matter in an object Weight- the force that gravity exerts on an object Law of conservation of matter- matter is neither created of destroyed; it is only transferred from one type or phase to another. Atom- the smallest particle of an element that has properties of that element; indivisible Molecule- consists of two or more atoms joined by strong forces called chemical bonds Pure substance – homogeneous substance that has a constant composition Elements – substance that is composed of a single type of atom; defined by the number of protons in the atom Compounds – pure substances that can be broken down via chemical changes Mixture – composed of two or more types of matter and can be separated by physical changes Heterogeneous mixture – a mixture that varies from point to point Heterogeneous mixture (solution) – a mixture that has a uniform composition and appears visually the same throughout Physical property – a characteristic of matter that is not associated with a change in its chemical composition Physical change – a change in the state or properties of matter without any accompanying change in its chemical composition Chemical property – an observable property of matter that undergoes a chemical reaction Chemical change – a change that always produces one or more types of matter that differ from the matter present before the change Extensive property- depends on the amount of matter present Intensive property- does not depend on the amount of matter present Kelvin scale- defined around the concept of absolute zero, the lowest temperature theoretically possible Celsius scale- defined around the freezing point and boiling point of water. Volume- measure the amount of space occupied by an object Density- the ratio of the mass of a sample of a substance and the volume it occupies Exact numbers- obtained only through the measurement of counting; has zero uncertainty; includes defined quantities Inexact numbers- obtained by any measurement other than counting; has a level of uncertainty Accuracy- tells how close a measurement is to the true value Precision- tells how close a series of replicate measurements are to another Conversion factor- a ratio of two equivalent quantities expressed with different measurement units 1.1 Macroscopic Microscopic Symbolic Large enough to be Visible through a Specialized language to directly sensed microscope represent components of macro/microscopic Ex: food Ex: viruses Ex: elemental symbols The scientific method: Observation Hypothesis experiment and observations If results are not consistent with the prediction, reform the hypothesis. When the results are consistent with the prediction, it will contribute to a body of knowledge. This can then become a law or a theory. Law Theory Hypothesis Summarize a vast Well sustained, testable A tentative explanation number of explanations of of observations that experimental particular aspects of acts as a guide for observations nature gathering and checking information 1.2 Solid Liquid Gas Fixed shape and volume Takes shape of the Expands to fill container container, forms horizontal surface, has a fixed volume Elemental- a molecule made of one element Classifying matter: Matter does it have constant properties and composition? yes: pure no: Mixture substance is it uniform can it be throughout? simplified chemically? no: yes: no: yes: heterogeneous homogeneous element compound 1.3 Examples of physical properties: Density, color, hardness, melting point, boiling point, and electrical conductivity Examples of chemical properties: Flammability, toxicity, acidity, and reactivity Reading the periodic table: Atomic number 1 H Symbol 1.008 Atomic mass hydrogen Name 1.4 Base units Property measured Name of unit Unit symbol Length Meter m Mass Kilogram kg Time Second s Temperature Kelvin K Electric current Ampere A Amount of substance Mole mol Luminous intensity candela cd Common unit prefixes Prefix Symbol Factor Femto f 10^-15 Pico p 10^-12 Nano n 10^-9 Micro µ 10^-6 Milli m 10^-3 Centi c 10^-2 Deci d 10^-1 Kilo k 10^3 Mega M 10^6 Giga G 10^9 Tera T 10^12 Temperature conversions K=˚C+273.15 ˚F=(9/5)x(˚C)+32 Time conversions 60s=1min; 60min=1hr; 24hrs=1day; 365days=1yr Volume=(length)^3 Density=mass/volume 1.5 Quantitative- objective Qualitative- subjective Rules for significant figures *you must be able to count sig figs* 1. Any non-zero 2. Zeros between non-zeros 3. Zeros next to the left of the first non-zero are NOT significant 4. Zeros to the right of the first non-zero number are significant IF there is a decimal point 5. Non explicit decimal points may or may not be significant 6. All exact numbers have infinite significant digits 7. In scientific notation (N*10^x), all the numbers for N are significant ROUNDING RULES! Addition and subtraction Round to the least number of decimal points Multiplication and division Round to the least number of significant digits 1.6 Example of using a conversion factor 1.5 inches to cm 1in=2.54cm 1.5in*(2.54cm/1in)
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