Chemistry Exam Vocab
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93 terms
Terms | Definitions |
|---|---|
 matter | anything that has mass and takes up space |
| atom | smallest unit of an element that maintains the chemical identity of that element |
| compound | a substance that can be broken down into simpler stable substances; each is made from the atoms of two or more elements that are chemically bonded |
| extensive property | depend on the amount of matter that is present (volume, mass, amount of energy); property that changes when the amount of the sample changes |
| intensive property | does not depend on the amount of matter that is present (boiling point, density melting point); property does not change if you takes some of it away |
| chemical property | relates to the substance's ability to undergo changes that transform it into different substances; properties that change the chemical formula of the matter; the substances behavior or how it acts |
| physical property | a characteristic that can be observed or measured without changing the identity of the substance; description; properties that do not changed the chemical structure of the matter |
| chemical change | a change in which one or more substances are converted into different substances; substance looks different in the end; produces a new substance |
| physical change | a change in a substance that does not involve a change in the identity of the substance; changes into different states of matter; does to produce a new substance |
| change of state | a physical change of a substance from one state to another (plasma--gas--liquid--solid) |
| plasma | high-temperature physical state of matter in which atoms lose most of their electrons |
| gas state | matter that has neither definite volume nor shape |
| liquid state | matter has definite volume but indefinite shape |
| solid state | matter that has definite volume and a definite shape |
| pure substance | has a fixed composition and differs from a mixture; consists of only one component |
| mixture | a blend of two or more kinds of matter, each of which retains its own identity and properties |
| homogenous mixture | mixture is uniform in composition (can't see the different particles) |
| heterogeneous mixture | mixture that is not uniform throughout (can see the different substances)` |
| colloid | a heterogeneous mixture in which particles are spread out throughout the whole substance |
| suspension | a heterogeneous mixture where the particles fall to the bottom after a certain amount of time |
| Tyndall effect | method to help distinguish a solution from a colloid where you shine a beam of light through the solution; if you can see the light on the other side then it is a solution; if you can't see it, then it is a colloid |
| groups | vertical columns on the periodic table |
| periods | horizontal rows of elements on the periodic table |
| metal | an element that is good at conducting heat and conducting electricity; solid at room temperature; malleable (can be rolled into sheets); ductile (can be rolled into wire; luster |
| non-metal | an element that is a poor conductor of heat and electricity; brittle; gas at room temperature |
| metalloid | an element that has characteristics of metals and some characteristics of non-metals; solid at room temperature; good at conducting heat and electricity, but not as good as metals |
| model | more than a physical object in science; it is often an explanation of how phenomena occur and data or events related |
| theory | a broad genarlization that explains a body of facts or phenomena |
| length | cursive l; m; meter |
| mass | m; kg; kilogram |
| time | t; second; sec |
| temperature | T; kelvin; k (celcius+273) |
| amount of substance | n; mole; mol |
| density | the ratio of mass to volume; physical property; as mass increases, the volume increases |
| conversion factors | a ratio derived from the equality between two different units that can be used to convert from one unit to the other |
| accuracy | refers to the closeness of measurements to the correct or accepted value of the quantity measured; if an experiment is very precise with the numbers and all the numbers are close to the actual value, it is very accurate |
| precision | refers to the closeness of a set of measurements of the same quantity made in the same way; if you do an experiment three times and get the same number all three times, the experiment is precise |
| percent error | calculated by subtracting accepted value from the experimental value, dividing the difference by the accepted value, and then multiplying it by 100 |
| leading zeros | NEVER SIGNIFICANT 0.24----- NO |
| captive zeros | ALWAYS SIGNIFICANT 303; 1.007-------YES |
| trailing zeros | ARE significant if they have a decimal and ARE NOT if there is no decimal 3.100-----YES; 3100------NO |
| direct proportion | two quantities are this to each other if dividing one by the other gives the constant value; as one variable increases, the other increases |
| inverse proportion | two quantities are this to each other if their product is constant; as one variable increases, the other decreases |
| Dalton's atomic theory | 1. atoms are tiny indivisible spheres 2. all atoms of an element are exactly alike 3. atoms of different elements are different 4. atoms of elements combine in simple whole number ratios to form compounds |
| JJ Thompson | did the cathode ray experiment and came up with the Plum Pudding model |
| Earnest Rutherford | did the gold foil experiment and came up with his model that said electrons are located outside of the nucleus instead of inside of it |
| atomic number | the number of protons of each atom of that element which is indicated by the number above the symbol |
| Bohr's model | model that stated the electrons where in specific rings around the nucleus |
| atomic mass | average mass of atoms of an element that is said below the symbol |
| isotopes | atoms of the same element that have different masses; they have different amounts of neutrons |
| average atomic mass | the weighted average of the atomic masses of the naturally occurring isotopes of an element |
| mole | the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12 (counting unit) |
| Avagadro's number | 6.022x10^23 |
| molar mass | the mass of one mole of a pure substance |
| Law of Conservation of Mass | mass is neither created nor destroyed |
| Law of Definite Proportions | no matter were elements come from, they are always the same |
| Law of Multiple Proportions | when two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers |
| electromagnetic spectrum | all the forms of electromagnetic radiation |
| wavelength | the distance between corresponding points on adjacent waves |
| frequency | the number of waves that pass a given point in a specific time, usually one second |
| photoelectric effect | the emission of electrons from a metal when light shines on the metal |
| quantum | the minimum quantity of energy that can be lost of gained by an aton |
| ground state | lowest energy state of an atom |
| excited state | a state in which an atom has a higher potential energy than it has in its ground state |
| spectrum | the characteristic wavelengths of electromagnetic radiation that is emitted or absorbed by an atom |
| emission | the spectrum of frequencies of electromagnetic radiation emitted by the element's atoms or the compound molecules when they are returned to a lower energy state; goes from the higher state to a lower state through a photon which creates light |
| absorption | energy of a photon is take up by matter |
| Heinsberg uncertainty principle | it is impossible to determine simultaneously both the position and velocity of an electron or any other particle |
| quantum theory | describes mathematically the wave properties of electrons and other very small particles |
| electron configuration | the arrangement of electrons in an atom |
| Aufbau principle | an electron occupies the lowest energy orbital that can receive it |
| Pauli exclusion principle | no two elements in the same atom can have the same set of four quantum numbers |
| Hund's rule | orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons is singly occupied orbitals must have the same spin state |
| valence electron | an electron that is found in the outermost shell of an atom and that determines the atom's chemical properties |
| core electron | an electron that is not a valence electron; every electron that is not up for bonding with |
| alkali metals | combine with non-metals; pure state they are silver and very soft; group 1 |
| alkaline-earth metals | hard and dense; group 2 |
| transition metals | high luster; good conductors of electricity; typical metallic properties; middle elements |
| halogens | elements of group 17; most reactive elements; create salts |
| acid | distinct type of molecular compound about which is classified as either binary or ternary |
| binary acids | acids that consist of two elements: hydrogen and one halogen |
| ternary acids | acids that contain hydrogen, oxygen, and a third element that is a non-metal |
| empirical formula | consists of the symbols for the elements combined in a compound, with subscripts showing the smallest whole-number mole ratio of the different atoms in the compound |
| molecular formula | the actual formula of a molecular compound |
| chemical reaction | the process by which one or more substances are changed into one or more substances; to know that a chemical reaction has taken place requires evidence that one or more substances have undergone a change in identity |
| precipitate | a solid that is produced as a result of a chemical reaction in solution that separates from the solution |
| synthesis reaction | A+X---->AX |
| decomposition reaction | AX---->A+X |
| single displacement reaction | A+BX---->B+AX |
| double displacement reaction | AX+BY---->AY+BX |
| combustion reaction | a substance combines with oxygen and producing H2O and CO2 |
| theoretical yield | amount of product produced from the limiting reactant |
| limiting reactant | the reactant that produces the least amount of product |
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