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chem midterm
midterm vocab
| Term | Definition |
|---|---|
| chemistry | Study of the composition and properties of substances, and the changes those substances can undergo |
| scientific method | Orderly and systematic approach to gathering info in order to answer questions about the world |
| observation | Fact that is noticed either quantitatively or qualitatively |
| hypothesis | Proposition and unproved explanation of observed facts (educated guess) |
| experiment | Carefully devised procedure for making observations and gathering data |
| conclusion | Judgement or opinion formed as a result of analyzing data |
| natural law | Description of a phenomenon that has been repeatedly and uniformly observed in nature |
| theory | Logical and time tested explanation of a phenomenon that occurs in the natural world |
| variable | Factor being tested In an experiment |
| experimental control | Factor that remains constant during an experiment |
| metric system | Decimal system of measurement used internationally |
| international system of units (SI) | System of units that is an extension of the metric system; includes 7 base units |
| base unit | One of seven units used in the SI system |
| mass | Quantify of matter in a unit |
| derived unit | Unit in the SI system that results in a combination of base units |
| volume | Amount of space that an object occupies |
| metric prefix | Syllable or group of syllables attached to the beginning of a metric unit in order to make the unit larger or smaller |
| precision | Measure of the agreement between the numerical values of two or more measurements that have been using the same method; when the same values result from repeated measurements, the measurements are said to have high ______ |
| accepted value | Standard value for a measurement |
| accuracy | Indicates how close a measurement is to it's accepted value |
| significant digit | Digit in the measurement that is certain, plus one digit that is estimated |
| percent error | Relative error as determined by finding the difference between an accepted value an d a measured value, dividing the result by the accepted value and multiplying the quotient by 100 |
| density | Mass of an object divided by its volume |
| dimensional analysis | Technique for converting between units by using the numerical relationships between the units by using the numerical relationships between the units |
| unit equality | Equation that shows the numerical relationships between 2 units |
| conversion factor | Fraction having a value of one that is written from a unit equality and is used to change a measurement from one unit to another |
| energy | Capacity to do work or transfer heat |
| kinetic energy | Energy of motion |
| potential energy | Stored energy or energy of position |
| joule | Basic unit of energy |
| law of conservation of energy | Natural law describing the fact that energy is neither created nor destroyed in any process |
| kelvin scale | S.I temperature scale with a zero point of absolute zero |
| absolute zero | Theoretically lowest temperature that can be reached -273.15 C or 0 K |
| matter | Anything that has mass and volume |
| solid | State at which matter holds a definite shape and volume |
| liquid | State in which matter does not hold a definite shape but does occupy a definite volume |
| gas | State in which matter doesn't have a definite shale or volume |
| physical property | Characteristic of a substance that can be observed without altering the identity of the substance |
| chemical property | Characteristic of a substance that can't be observed without altering the identity of the substance |
| physical change | Process by which a substance undergoes a change that does not alter its identity |
| chemical change | Process by which the composition and properties of a substance change, thus altering the identity of the substance. Products a new substance |
| Avogadro's number | 6.02 x 10*23 |
| element | Substance that can't be separated into a similar substance by a chemical change |
| compound | Substance that contains two or more elements chemically combined |
| pure substance | Substance made of one kind of material with a unique set of chemical and physical properties |
| mixture | Blend of two or more pure substances that are not chemically combined |
| heterogeneous mixture | Mixture in which the particles are not uniformly intermingled and that therefore has visibly different parts |
| homogeneous mixture | Mixture in which the particles are uniformly intermingled and that therefore doesn't have visibly different parts |
| atom | Smallest particle of an element that retains the chemical identity of that element |
| law of constant composition | Natural law describing the fact that a given compound always contains the same elements in the same properties |
| atomic theory of matter | Proposed by john dalton. States that atoms are neither created nor destroyed in a chemical reaction, all atoms of the same element are identical but not to other atoms |
| cathode ray | Stream of electrons emitted by a negatively charged electrode and attracted by a positively charged electrode |
| cathode ray tube | Evacuated glass tube in which a stream of electrons emitted by a cathode strikes a fluorescent material causing it to glow |
| electron | Negatively charged particle in an atom |
| radioactivity | Spontaneous emission of radiation from an atom |
| nucleus | Concentrated core of an atom, which contains protons and neutrons |
| proton | Positively charged particle in the nucleus of an atom |
| neutron | Neutral particle in the core of an atom |
| atomic number | Number of protons in the nucleus |
| atomic mass unit | Unit by which the mass of an atom or the atomic particle is expressed. |
| ion | Atom or group of atoms that has a positively or negative charge because it has lost or gained electrons |
| isotope | Atom that has the same number of protons as another atom but has a different number of neutrons |
| mass number | Sum of the number of protons and neutrons in the nucleus of an atom |
| atomic mass | Weighted average of the masses of the existing isotopes of an element |
| nuclear reaction | Process that changes the composition of the nucleus of an atom |
| strong nuclear force | Attractive force between the particles in the nucleus. In a stable atom, it overcomes the force of repulsion |
| radioactive decay | Spontaneous breakdown of an unstable atomic nucleus |
| nuclear equation | Equation that describes the changes that occur during radioactive decay |
Created by:
hannahorth98
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