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Unit three chemistry
vocabulary terms for unit three
| Term | Definition |
|---|---|
| Dalton's atomic theory | states that matter is composed of extremely small particles called atoms; atoms are invisible and indestructible; atoms of a given element are identical in size, mass and chemical properties; atoms of a specific element are different from those of anothe |
| atom | smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed of electrons, protons, and neutrons |
| cathode ray | radiation that originates from the cathode and travels to the anode of a cathode-ray tube |
| electron | negatively charged, fast moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom's nucleus. |
| neutron | a neutral subatomic particle in an atom's nucleus that has a mass nearly equal to that of a proton. |
| nucleus | extremely small positively charged, dense center of an atom that contains positively charged protons and neutral neutrons. |
| proton | subatomic particle in an atoms nucleus that has a positive charge of +1 |
| atomic mass | weighted average mass of the isotopes of that element |
| atomic mass unit (amu) | 1/12 the mass of a carbon-12 atom |
| atomic number | the number of protons in an atom |
| isotope | atoms of the same element with different number of neutrons |
| mass number | number of an elements name representing the sum of its protons and neutrons. |
| states of matter | physical forms in which all matter naturally exists on Earth- most commonly as a solid, liquid or gas |
| solid | form of matter that has its own definite shape and volume, is incompressible and expands only slightly when heated |
| liquid | form of matter that flows, has constant volume and takes the shape of its container |
| gas | form of matter that flows to conform to the shape of its container, fills the containers entire volume and is easily compressed |
| vapor | gaseous state of a substance that is a liquid or solid at room temperature |
| physical properties | characteristic of matter that can be observed or measured without changing the sample's composition |
| extensive properties | physical properties, such as mass, length and volume, this is dependent upon the amount of substance present |
| intensive properties | physical property that remains the same no matter how much of a substance is present. |
| chemical properties | ability or inability of a substance to combine with or change into on or more new substances |
| physical change | type of change that alters the physical properties of a substance but does not change its composition |
| phase change | transition of matter from one state to another |
| chemical change | process involving one or more substances changing into new substances also called a chemical reaction. |
| law of conservation of mass | states that mass is neither created nor destroyed during a chemical reaction but is conserved. |
| mixture | physical blend of 2 or more pure substances in any proportion in which each substance retains its individual properties; can be separated by physical means. |
| homogenous mixture | one that has a uniform composition throughout and always has a single phase; also called a solution |
| solution | uniform mixture that can contain solids, liquids or gases also called a homogenous mixture. |
| filtration | technique that uses a porous barrier to separate a solid from a liquid |
| distillation | technique that can be used to physically separate most homogenous mixtures based on the differences in the boiling point of surface |
| crystallization | separation technique that produces pure solid particles of substance from a solution that contains the dissolved substances. |
| sublimation | energy requiring process by which a solid changes directly to a gas without first becoming a liquid |
| chromatography | technique used to separate the components of a mixture based on the tendency of each component to travel or to be drawn across the surface of another material. |
| element | pure substances that cannot be broken down into simple substances by physical or chemical means |
| periodic table | chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (groups or families) arranged by increasing atomic number. |
| compound | chemical combination of 2 or more different elements can be broken down into simpler substances by chemical means and has properties different form its component elements. |
| law of definite proportion | states that regardless of the amount a compound is always composed of the same elements in the same proportion by mass |
| percent by mass | percent determined by the ratio of the mass of each element to the total mass of the compound |
| law of multiple proportions | states that when different compounds are formed by combination of the same elements, different masses of one element combine with the same mass of the other element in a ratio of small whole numbers |
| heterogeneous mixture | one that does not have a uniform composition and in which the individual substance remain distinct |
| electron dot structure | consists of an elements symbol, representing the atomic nucleus and inner-level electrons, surrounded by dots, representing the atoms valence electrons |
| valence electron | electrons in an atoms outermost orbitals; determine the chemical properties of an element |
| Hund's rule | state the single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals |
| Pauli exclusion principle | states that the maximum of two electrons can occupy a single atomic orbital but only if the electrons have opposite spins. |
| Aufbau principle | states that each electron occupies the lowest energy orbital available |
| electron configuration | the arrangement of electrons in an atom, which is prescribed by 3 rules; Aufbau, Pauli exclusion, and Hund's rule |
| energy sublevels | energy levels contained within a principal energy level |
| principal energy level | major energy levels of an atom |
| ground state | lowest allowable energy state of an atom |
| atomic orbital | three dimensional region around the nucleus of an atom that describes an electrons probable location. |
Created by:
mrsklann
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