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CHEM1211 Exam 1
| Question | Answer |
|---|---|
| Scientific Method | process of studying natural phenomena, involving observations, forming laws and theories, and testing of theories by experimentation |
| Observations | qualitative vs quantitative observations |
| Qualitative | descriptive of qualities, characteristics, etc. (color, smell appearance) |
| Quantitative | deals with specific numbers and values (volume, speed, time, mass) |
| Hypothesis | a possible explanation for an observation |
| Experiment | carried out to test the hypothesis |
| Theory (model) | a set of assumptions put forth to explain some aspect of observed behavior |
| Natural Law | a statement expressing generally observed behavior |
| Law vs Theory | a law is a summary of what happens a theory is an attempt to explain why it happens |
| Matter | material of the universe, defined as anything occupying space and having mass |
| Solid | rigid, fixed volume and shape; slightly compressible |
| Liquid | definite volume; no specific shape; slightly compressible |
| Gas | no fixed volume or shape; highly compressible |
| Matter | can be broken down into two general parts: pure substances and mixtures |
| Matter can be broken down into? | Mixtures and pure substances |
| Pure substance | A substance with constant composition |
| What are some examples of pure substances? | Sugar, water |
| Pure substances can be broken down into? | Compounds and elements |
| Compound | A substance that can be further broken down into its constituent elements by chemical processes |
| Elements | A substance that cannot be further broken down into anything simpler |
| What are the diatomic molecules you should memorize | H2,N2,O2,F2,Cl2,Br2,I2,P4,S8 |
| Most elements exist in nature as individual atoms that are? | Monatomic |
| Molecules | Two or more atoms held together by chemical bonds |
| Can all compounds be called molecules? | Yes |
| Can all molecules be compounds? | No |
| Mixture | A substance with variable composition |
| What are some examples of mixtures? | Wood, gasoline, soil |
| Homogenous mixture | Having visibly indistinguishable parts; can also be called a solution |
| Heterogenous mixture | Having visibly distinguishable parts |
| What are some ways to separate mixtures? | Distillation and filtration |
| Distillation | A method of separation that depends on the boiling points of a liquid mixture to separate them |
| Filtration | A method of separation involving a solid and a liquid. The mixture is passed through a mesh allowing the liquid to pass, leaving behind the solid |
| Law of Conservation of Mass | Mass is neither created nor destroyed |
| Law of Definite Proportion (or Constant Composition) | A given compound always contains the same proportion of elements by mass |
| Law of Multiple Proportions | ??? |
| Extensive property | A property that depends on the amount of matter in a sample |
| Intensive property | A property that is independent on the amount of matter in a sample |
| Density | The mass of a substance per unit of volume |
| Physical change | Change in the form of a substance, but not in the actual chemical composition |
| What are some examples of physical changes? | Ice melting, water boiling off, cutting a sheet of paper |
| Chemical change | Change in the chemical composition of a substance |
| What are some examples of chemical changes? | Iron rusting, wood burning, baking a cake |
| Physical property examples | Odor, taste, color, appearance, melting/boiling point, conductivity, density |
| Chemcial property examples | Flammability, corrosiveness, reactivity |
| Law of Conservation of Energy | Energy cannot be created or destroyed, but it can be transferred; the total energy of the universe is constant |
| What is proper practice when making a measurement? | Record all the certain digits plus the first uncertain digit |
| Accuracy | Refers to the agreement of a particular value with the true value |
| Precision | Refers to the degree of agreement among several measurements of the same quantity; looks at reproducibility |
| Are nonzero integers counted as significant figures? | Yes |
| Are leading zeros significant figures? | No |
| Are captive zeros significant figures? | Yes |
| Are trailing zeros significant figures? | Yes if the number contains a decimal point |
| How to report value with multiplication and division? | Value with the smallest number of sig figs |
| How to report value with addition and subtraction? | Value with the smallest number of decimal places |
| What are atoms composed of? | Protons, neutrons, electrons |
| What is in the nucleus of atoms? | Protons and neutrons |
| Ion | Atom or group of atoms with a positive and negative charge |
| Polyatomic ion | An ion containing many atoms |
| Isotopes | Atoms with the same number of protons, and a different number of neutrons |
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