Chemistry review
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91 terms
Terms | Definitions |
|---|---|
 chemical bond | a mutual electrical attraction between the nuclei and valence electrons of different atoms that binds the atoms together |
| covalent bonding | a chemical bond resulting from the sharing of an electron pair between two atoms |
| ionic bonding | the chemical bond resulting from electrical atrraction between large numbers of cations and anions |
| nonpolar-covalent bond | a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge |
| polar | having an uneven distribution of charge |
| polar-covalent bond | a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons |
| bond energy | the energy required to break a chemical bond and form neutral isolated atoms |
| bond length | the distance between two bonded atoms at their minimum potential energy, that is, the average distance between two bonded atoms |
| chemical formula | a formula that indicates the relative numbers of atoms of each kind in a chemical compound by using atomic symbols and numerical subscripts |
| diatomic molecule | a molecule containing only two atoms |
| double bond | a covalent bond produced by the sharing of two pairs of electron between two atoms |
| electron-dot notation | an electron configuration notation in which only valence electron of an atom of a particular element are shown, indicated by dots placed around the elements' symbol |
| Lewis structures | formulas in which atomic symbols represent nuclei and inner-shell electrons, dot-pairs or dashes between two atomic symbols represent electron pairs in covalent bonds, and dots adjacent in only one atomic symbol represent unshared electrons |
| lone pair | a pair of electrons that is not involved in bonding and that belongs exclusivly to one atom |
| molecular compound | a chemical compound whose simplest units are molecules |
| molecular formula | a formula showing the types and numbers of atoms combined in a single molecule of a molecular compound |
| multiple bond | a double or triple bond |
| octet rule | chemical compounds tend to form so that each atom, by gaining, losing, or sharing electrons has an octet of electrons in its highest occupied energy level |
| resonance | the bonding in molecules or ions that cannot be correctly represented by a single Lewis structure |
| single bond | a covalent bond produced by the sharing of one pair of electrons between two atoms |
| structural formula | a formula that indicates the kind, number, arrangement, and bonds but not the unshared electron pairs of the atoms in a molecule |
| triple bond | a covalent bond produced by the sharing of three pairs of electrons between two atoms |
| unshared pair | a pair of electrons that is not involved in bonding and that belongs exclusivly to one atom |
| formula unit | the simplest collection of atoms from which an ionic compound's formula can be established |
| ionic compound | a compound composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal |
| lattice energy | the energy released when 1 mole of an ionic crystalline compound is formed from gaseous ions |
| polyatomic ion | a charged group of covalently bonded atoms |
| ductility | the ability of a substance to be drawn, pulled, or extruded through a small opening to produce a wire |
| malleability | the ability of a substance to be hammered or beaten into thin sheets |
| metallic bonding | chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons |
| gas | has no definate shape and no definate volume |
| reactants | elements or compounds found on the left side of a reaction sentence. The original substances in a reaction |
| matter | anything that has mass and takes up space |
| mass | a measure of the quantity of matter |
| kilogram | SI unit for mass |
| second | SI unit for time |
| milliliter | the SI unit for measuring a small amount of liquid |
| kelvin | the SI unit for temperature |
| cubic centimeter | equal to a milliliter-used to measure the volume of a solid |
| density | mass divided by volume, the amount of mass in a given volume |
| isotope | one of two or more atoms with the same atomic number but with different numbers of neutrons |
| allotrope | a structurally different form of an element; graphite and a diamond are allotropes, having the same formula but different structure to the atoms |
| pure substance | a sample of matter, either a single element or a single compound, that has definite chemical and physical properties |
| chemical formula | a combination of chemical symbols and numbers to represent a substance |
| chemical energy | energy stored in chemical bonds |
| law of conservation of energy | energy cannot be created or destroyed |
| specific heat | the heat required to raise the temperature of one gram of a substance one degree centigrade |
| significant figures | all the digits that can be known precisely in a measurement, plus a last estimated digit |
| scientific notation | a way of expressing a value as the product of a number between 1 and 10 and a power of 10 |
| law of conservation of mass | the law that states that mass cannot be created or destroyed in ordinary chemical and physical changes |
| John Dalton | The first person to propose an atomic theory based on scientific knowledge |
| Dmitri Mendeleev | The first person to successfully place elements in a predictable pattern and predict properties of unknown elements |
| law of definite proportions | the fact that a chemical compound contains the same elements in exactly the same proportions by mass regardless of the size of the sample or source of the compound |
| cathode ray experiment | An experiment that showed that electrons had mass and a charge |
| gold foil experiment | An experiment where protons were passed through and deflected from a thin sheet of metal, proving that an atom contained a concentrated nucleus and a lot of surrounding space. |
| Ernest Rutherford | Responsible for the gold foil experiment. |
| strong force | a strong attraction between protons and neutrons that overwhelms the electromagnetic repulsion forces when the nucleons are in close proximity. |
| Bohr | a Danish physicist (1885-1962); created a new atomic model; described electrons as moving around the nucleus in fixed orbits and having a set amount of energy |
| principal quantum number | The main energy level of an atom |
| Hund's rule | electrons having parallel spins will enter unoccupied orbitals one at a time before pairing up |
| Aufbau principle | electrons enter orbitals of lowest energy first |
| Pauli Exclusion principle | no two electrons in the same atom can have the same set of four quantum numbers |
| electron configuration | the arrangement of electrons in an atom |
| alloy | a solution of two or more metals |
| halogens | group 17; contains nonmetals; 7 electrons in its outermost energy level; very reactive; poor conductors of electric current; never in its uncombined form in nature; combine with most metals to form salts |
| alkali metals | Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium |
| earth-alkali metals | Group 2, 2 electrons in outer level, less reactive than alkali metals. Silver, shiny, low density; Berrilium, Magnesium, Calcium, Strontium, Barium, Radon |
| noble gases | Contains nonmetals that are unreactive. Full outermost energy level except helium which has 2. |
| actinide series | (chemistry) a series from actinium to lawrencium of 15 radioactive elements with increasing atomic numbers |
| lanthanide series | the rare-earth elements with atomic numbers 57 through 71 |
| transition metals | Groups 3-12, 1-2 electrons in the outer energy level, less reactive than alsali-earth metals, shiny, good conductor of thermal energy and electrical current, high density |
| metalloids | semiconductors, border the zigzag line, shiny, brittle, hard, at high temp- good conductors of electric current |
| transmutation | The process of changing one element into another |
| anion | an ion with a negative charge |
| cation | an ion with a posotive charge |
| nuclide | An atom that is identified by the number of protons and neutrons in its nucleus |
| nucleon | a proton or neutron |
| alpha particle | A particle, much like a He atom, that is sometimes emitted during radioactive decay. Usually happens in molecules that are very large. |
| beta particle | A particle, much like an electron, that is sometimes emitted during radioactive decay. Emission causes a neutron to change to a proton. |
| positron | A particle that has the same mass as an electron but is positively charged and is sometimes emitted during radioactive decay. Emission causes a proton to change to a neutron. |
| gamma ray | electromagnetic radiation emitted during radioactive decay and having an extremely short wavelength |
| decay series | a series of radioactive nuclides produced by successive radioactive decay until a stable nuclide is reached |
| fission | a nuclear reaction in which a massive nucleus splits into smaller nuclei with the simultaneous release of energy |
| fusion | a nuclear reaction in which nuclei combine to form more massive nuclei with the simultaneous release of energy |
| chain reaction | a reaction in which the material that starts the reaction is also one of the products and can start another reaction |
| half-life | time is takes for 50% of the parent material to be converted into the daughter isotope |
| rem | (Roentgen Equivalent Man) the dosage of ionizing radiation that will cause the same amount of injury to human tissue as 1 roentgen of X-rays |
| rad | a unit of absorbed ionizing radiation equal to 100 ergs per gram of irradiated material |
| roentgen | used to measure the intensity of radiation in x-rays |
| electron cloud | a region around the nucleus of an atom where electrons are likely to be found. |
| valence electrons | Electrons that occupy the highest energy level of an atom. These electrons determine the reactivity of an atom. |
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