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College Bio Ch 2
The Chemical Basis of Life
| Question | Answer |
|---|---|
| Matter | anything that occupies space and has mass and is composed of chemical elements |
| Element | a substance that cannot be broken down to other substances |
| Trace Elements | essential for life but required in small amounts |
| Compound | a substance consisting of two or more different elements combined in a fixed ratio |
| Atom | the smallest unit of matter that still retains the properties of an element and consist of the subatomic particles |
| Subatomic Particles | protons, neutrons, electrons |
| Proton | has a single positive electrical charge |
| Electron | has a single negative electrical charge |
| Neutron | is electrically neutral |
| Nucleus | center of an atom where neutrons and protons are stored |
| Atomic Number | number of protons in an atom |
| Mass Number | the sum of the protons and neutrons in the nucleus |
| Isotopes | have the same number of protons and electrons but different numbers of neutrons |
| Radioactive Tracers | are frequently used in medical diagnosis |
| Positron-Emission Tomography (PET) | detects the location of injected radioactive materials- useful for medical diagnosis |
| Chemical Bonds | attractions between atoms |
| Ion | atom or molecule with an electrical charge resulting from gain or loss of electrons |
| Ionic Bond | when two ions with opposite charges attract and then hold on to each other- transfer of electrons |
| Covalent Bond | when atoms share outer-shell electrons |
| Molecule | formed when atoms are held together by covalent bonds |
| Electronegativity | the attraction (pull) for shared electrons |
| Nonpolar Covalent Bonds | electrons are shared equally between two atoms of similar electronegativity |
| Polar Covalent Bonds | Between atoms that differ in electronegativity. Shared electrons are pulled closer to the more electronegative atom, making it slightly negative and the other atom slightly positive. |
| Polar Molecules | molecules with an unequal distribution of charges- H2O |
| Hydrogen Bonds | A weak polar covalent bond in which the partially positive hydrogen atom in one molecule is attracted to the partially negative atom in another molecule |
| Cohesion | molecules sticking together |
| Surface Tension | a measure of how difficult it is to break the surface of a liquid- broken by hydrogen bonds |
| Heat | the energy associated with movement of atoms and molecules in matter |
| Temperature | measures the intensity of heat |
| Solution | a liquid consisting of a uniform mixture of two or more substances |
| Solvent | dissolving agent |
| Solute | substance that is dissolved |
| Acids | chemicals that can contribute hydrogen to a solution |
| Bases | chemicals accept hydrogen ions and remove them from solution |
| pH Scale | (pH=potential of hydrogen) is used to describe whether a solution is acidic or basic |
| Acid Precipitation | rain, snow, or fog with a pH lower than 5.6 |
Created by:
AZoller
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