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science
| Term | Definition |
|---|---|
| Scientific Method Definition | an organized plan for gathering, organizing, and communicating information |
| Goal of scientific method | to solve a problem or understand an event |
| Scientific Method Step #1 | Make an observation and identify a problem |
| Scientific Method Step #2 | Hypothesis - make an educated guess to solve problem (must be testable) |
| Scientific Method Step #3 | Test the hypothesis |
| Scientific Method Step #4 | Drawing conclusions - a conclusion may prove or disprove a hypothesis (hypothesis can be revised if not supported) |
| Scientific Method Step #5 | Develop a theory, a well tested explanation for a set of observations or experimental results about the natural world |
| What is a variable? | any part of the experiment that can be changed |
| Independent variable | the variable that is changed by experimenter (I change it) |
| Dependent variable | the variable that changes because independent variable is changed (dependent on what independent variable does) |
| Controlled variables | any variables that are not independent or dependent, CANNOT be changed |
| Control group | a group that does not change any variables, allows experimenter to observe changes from factors they may have missed |
| Scientific Law | a hypothesis that has been tested repeatedly and not been contradicted, summarizes a pattern in nature |
| Scientific model | a representation of an object or event, helps to understand things that can't be observed directly, can be changed with new ideas |
| beaker | large scale reactions, estimate volume |
| micro well plate | microscale reactions and multiple reactions |
| pipet | obtain liquids |
| scoopula | obtain solid |
| forceps | obtain small solids |
| test tube | small scale reactions |
| test tube holder | holds test tubes |
| test tube tongs | hold test tubes during heating |
| graduated cylinder | measure volume |
| hot plate | heat source |
| thermometers | measure temp |
| watch glass | lid, weigh dish, put out beaker fires |
| triple beam balance | obtain mass |
| ring stand | extra support to hold/heat items |
| utility clamp | attaches to ring stand for support |
| when to report accidents to teacher in lab | IMMEDIATELY no matter how minor |
| if clothing catches fire | STOPDROPROLL |
| when read activity | BEFORE entering lab |
| work alone in laboratory? | NEVERRRRRRR |
| lab outfit? | apron, safety goggles, contacts OK as long as safety goggles (tell teacher abt them), tie back hair |
| significant figures | the digits in a measurement that are certain + one digit that is estimated, used when recording measurements and doing calculations |
| what counts as SIG FIG | the last digit, all non zero numbers, FOLLOW ZERO RULES |
| zero rules | leading zeros - NEVER significant (0.00027 has two sig figs), Numbers between non zero numbers - significant (20.0003 all six are sig figs), Trailing zeros - NOT significant unless decimal point is shown |
| general rule for all sig fig operations? | answer can have no more sig figs than measurement with the least amount of sig figs |
| multiplication and division sig figs | number of sig figs of the result is the same as the least number of sig figs in multipliers |
| addition and subtraction sig figs | result must have same number of DECIMAL PLACES as the term with least number of decimal places |
| how many sig figs? 1.2340 | 5 sig figs |
| 1.421 + 0.4372 (sig figs) | 1.858 |
| 42.3 x 2.61 (sig figs) | 110. |
| scientific notation | a number expressed as the product of two factors, the first is a number falling between 1-10, the second is a power of ten |
| scientific notation 8,653,000. | 8.635 x 10'6 |
| scientific notation multiplication | multiply factors and add exponents |
| scientific notation division | divide the numbers, subtract exponent in denominator from one in numerator |
| scientific notation addition and subtraction | express all numbers to same power of ten (change decimal places) |
| pie/circle graph | used to show parts of a whole |
| bar graphs | Used to compare amounts |
| line graphs | used to show change of one piece of info in relation to another change |
| median | middle number in a set of data |
| mode | The number that occurs most often in a set of data |
| Precision | a number that indicates the consistency of a set of measurements |
| accuracy | a number indicating how near a measurement or set of measurements is to an accepted value |
| percent error | a number that indicates the accuracy of a measurement |
| standard deviation | a number that indicates the precision of a measurement |
| metric ruler | measures length |
| direct proportion | a relationship in which the ratio of two variables is constant; straight line |
| deci | 0.1 |
| centi | 0.01 |
| milli | 0.001 (a thousandth) |
| deka | 10 |
| kilo | 1000 |
| hecta | 100 |
| technology | using science to solve a problem |
| SI | international system of units |
| conversion factor | a ratio of equivalent measurements |
| SI mass base | kilogram |
| controlled experiment | only one variable is manipulated at a time |
| data | facts or statistics collected together for reference or analysis |
| mass | amount of matter in an object |
| derived unit | a unit that is defined by a combination of base units |
| what measurement system does the US use? | customary/imperial system |
| Factor-label method | A problem-solving procedure in which equations are set up so that unwanted units cancel and only the desired units remain. |
| length | Distance between two points |
| volume | amount of space an object takes up |
| unit | a known amount of measurement |
| SI unit of temp | kelvins |
| The most commonly used frame of reference? | earth |
| static friction | acts on objects that are not moving |
| sliding friction | acts on an object as it slides over a surface |
| rolling friction | acts on rolling objects |
| fluid friction | acts on object moving through a fluid (liquid or gas) |
| friction | A force that opposes motion between two objects that touch as they move past each other |
| motion | a change in position relative to a frame of reference |
| force | a push or pull that changes the motion of an object |
| Newtons (N) | unit of force |
| balanced forces | combine to produce a net force of zero with no change in motion |
| unbalanced forces | produces a non zero netforce, object accelerates |
| strong force | binds protons and neutrons together, pulls objects together |
| gravity | force of attraction between two objects, depends on mass and distance between objects |
| air resistance | depends on velocity of a moving object |
| free fall | motion due to influence from gravity ALONE |
| terminal velocity | constant speed that an object reaches due to air resistance, acceleration is zero |
| inertia | an objects resistance to a change in motion |
| Newtons first law | An object at rest remains at rest, and an object in motion remains in motion at constant speed and in a straight line unless acted on by an unbalanced force (inertia) |
| weight | pull of gravity on a mass (N) NOT EQUAL TO MASS |
| Newtons 2nd law | The acceleration of an object depends on the mass of the object and the amount of force applied (F=ma) |
| net force | total amount of force, same directions added, opposite directions subtracted |
| Newton's Third Law | For every actions there an equal opposite reaction (there is ALWAYS an action and reaction force) |
| Law of Conservation of Momentum | The momentum of objects in an isolated is constant unless external force is applied |
| Instaneous speed | the speed something has at a specific instant |
| average speed | total distance over a unit of time |
| frame of reference | what speed is relative too |
| velocity | how fast something is going + in what direction |
| vectors | have magnitude (how much) and direction |
| acceleration | a rate of change in velocity |
| linear vs nonlinear graph | linear: straight line, nonlinear: curved line |
| constant acceleration | velocity changing at a constant rate |
| resultant vector | the sum of two or more vectors |
| relative motion | motion compared to a frame of reference |
| displacement | change in position of an object from the starting point (how far) |
| slope of distance time graph? | speed |
| projectile motion | motion of an object thrown in the air |
| weak force | responsible for the radioactive decay of nucleus in atoms (starts the process of fusion in stars) |
| electromagnetic force | occurs between electrically charged particles, like charges repel and opposites attract |
| acceleration due to gravity? | 9.8 m/s^2 |
| aristotle | claimed heavy objects fall faster than lighter ones and moving objects must continue to have force applied to keep moving |
| galileo | proved all objects fall to ground together, showed objects can continue to move without additional forces (inertia) |
| Equilibrium | when forces are balanced, net force of zero???? |
| static equilibrium | object is at rest |
| dynamic equilibrium | object has a constant velocity |
| proton | equal to atomic number, positive charge |
| neutron | no charge, subtract mass number - atomic number |
| electron | negative charge, mass = 0, equal to number of protons |
| atomic number | equal to number of protons |
| mass number | number of protons + number of neutrons |
| neutral atoms | have an equal number of protons and neutrons |
| ion | atoms that aren't neutral |
| isotopes | Atoms of the same element that have different numbers of neutrons (most common is U-238 which doesn't split easily) |
| radiation | occurs when an unstable nucleus breaks down and emits energy and particles |
| alpha particle | positively charged, 2 protons and 2 neutrons, large size, can be stopped by paper |
| beta particle | comes from inside nucleus, high speed electron, has a single negative charge, can be stopped by a book |
| gamma rays | energy rays w no mass or charge and very high energy, will pass through most materials, dangerous |
| cloud chamber | used to detect sub-atomic particles, can see vapor trail |
| nuclear fission | nucleus is struck with particles and splits, E=mc2 |
| Nuclear fussion | 2 nuclei are pushed together to make a heavier nucleus, star power |
| half-life | time it takes for half of a radioactive sample to decay |
| nucleons | particles in the nucleus |
| wavelength | the distance from peak to peak, how electromagnetic radiation is measured |
| photon | discrete bundle of energy that makes up light |
| transmutation | the process that changes one element into another |
| quarks | all nucleons are made of a combination of three |
| atomic spectrum | the spectrum of electromagnetic radiation emitted or absorbed by electrons during transitions between energy levels |
| energy level | energy of the orbital of an electron |
| atomic orbital | describes location location and wave-like behavior of an electron |
| Dalton's Atomic Theory (1803) | 1) elements are composed of indivisible particles called atoms (INCORRECT, atoms are made of smaller particles ((electrons, protons, and neutrons))) 2) atoms of same element are identical (INCORRECT, they can have different masses) + 3 and 4 correct |
| electromagnetic forces | keeps electrons in orbit around nucleus |
| Antoine Lavoisier | (1700) Law of Conservation of Mass, the total mass before a chemical reaction is exactly equal to the total mass after a reaction |
| Joseph Proust | (1799) Law of Definite Proportions, the proportion by mass of the elements in a given compound is always the same |
| John Dalton | (1800) Law of Multiple Proportions, if there are two or more compounds that contain the same two elements, the masses of one element that combine with a fixed mass of the second element form a simple whole number ratio |
| J.J. Thomson (1856-1940) | Observed the effect of magnetic and electrical fields on the cathode rays. Hypothesis: Cathode rays are negatively charged particles (now called electrons) plum pudding model |
| Ernest Rutherford (1909) | Observed that alpha particles bombarding a gold foil, seeing the pattern that most particles pass directly through the gold foil, but a small fraction of the particles were deflected (nuclear model) |
| Niels Bohr (1913) | Studied the bright line and absorption spectrum of atoms Hypothesis: There are certain definite orbits in which an electron can travel around the nucleus (Bohr Model) |
| Erin Shrodinger (1887-1961) | Charged/electron cloud model: The path of electrons are not shown in the model, electrons are represented as a diffuse cloud of negative charge |
| The electron-cloud model | No way to determine just where or how fast electron is moving, cloud-like region where an electron with a particular energy might be, denser where more likely to be |
| radioactivity | occurs naturally and is with us all the time, makes life possible |
| alpha decay | 4 particles are ejected by the nucleus, 2 protons and 2 neutrons, forms new element |
| beta decay | neutron is converted into a proton, electron is ejected from the nucleus, forms new element |
| artifical transformation | bombarding an isotope with a particle, creating a change in the nucleus |
| chain reaction | when nuclear fission, the free neutrons can hit other nuclei and cause them to split and frees more neutrons |
| critical mass | the minimal mass of a fissionable material that will sustain a chain reaction |
| nuclear reactor - 3 main parts | nuclear fuel - mainly U-238 Control rods - usually cadmium or boron to absorb nuetrons Liquid - usually water |
| thermonuclear reaction | fusion is brought about by high temp (reaction in hydrogen bomb) |
| isotopic dating | Determining the age of a rock or mineral through how much C-14 is left (only effective for objects under 50,000 years old) or other radiative materials like uranium |
| Democritus (460-370 BC) | Greek philosopher that said all matter is made of tiny particles called "atomos" or atoms |
| solid | has a definite shape and volume, molecules vibrate quickly in fixed positions (close together) |
| liquid | definite volume, but indefinite shape, molecules move easily past each other |
| gases | no definite shape or volume, fast freely moving molecules |
| plasma | very hot gas made of particles that have an electric charge, suns and stars (rare on earth) |
| property | identifying trait or characteristic |
| physical property | can be observed or measured without changing composition - color, density, melting point, boiling point, hardness, freezing point, luster, shape texture |
| chemical properties | substance changes chemical identity, atoms rearrange to make new substance - flammability, dissolving, taste, rusting, react to form something, odor, color change |
| physical change | substance changes physical properties without changing chemical identity, can be more easily observed |
| chemical change | substance changes chemical identity, results in a release of energy |
| density | how many atoms there are in a certain amount of space, the more dense something is the heavier d=m/v |
| kinetic theory | matter is composed of small particles that are in constant motion, colliding with each other and the walls of their container |
| kinetic energy | energy of the motion/speed of particles, causes changes of state, hotter = faster, theoretically motion stops at absolute zero (0 Kelvin) |
| matter | Anything that has mass and volume |
| pure substance | has a fixed composition (all are the same) |
| mixture | different substances sharing the same space, can be separated by physical means |
| element | a fundamental material consisting of one type of atom, 120 of them that are organized by atomic number in periodic table (H or Fe) |
| molecule | two or more atoms bonded together (O2 or H2O) |
| compound | materials in which atoms are different elements are chemically bonded, have different properties from the elements they are made from (NaCl) |
| distillation | recollecting a vaporized substance based on boiling point EX: separating water from seawater, dry salts remain |
| filtration | separates materials based on the size of their particles |
| evaporation | The change of a substance from a liquid to a gas (can be used as a method of seperation) |
| heterogeneous | parts of a mixture are noticeably different |
| homogenous | substances are so evenly distributed that it's difficult to tell the different |
| solution | when substances dissolve and form a homogenous mixture, smaller particles EX: tap water |
| suspension | a heterogeneous mixture that separates into layers over time, larger particles |
| colloid | particle size is in between a suspension and a solution (medium), scatter light EX milk, fog |
| melting point | the temperature at which a solid changes to a liquid |
| flammability | ability to burn/set on fire |
| electrical conductivity | ability to transfer an electric current |
| reactivity | the speed at which something combines or reacts with others |
| boiling point | The temperature at which a liquid changes to a gas |
| malleability | the ability of a substance to be hammered or beaten into thin sheets without breaking |
| viscosity | a liquid's resistance to flow |
| thermal conductivity | The ability of an object to transfer heat |
| ionic compounds | a metal and a nonmetal, has the IDE ending |
| covalent compound | two nonmetals, uses Greek prefixes |
| polyatomic compounds | 3 or more elements (chart) |
| atomic radius | the size of an atom, decreases from left to right (more attraction between protons and electrons, increases from top to bottom (more electron rings) |
| ionization energy | the amount of energy required to remove an electron from an atom, forming a positively charged ion, increases from left to right (greater nuclear charge), decreases from top to bottom |
| Groups/columns/families | the elements in vertical columns that share similar chemical properties |
| period/rows | rows on the periodic table based on the regular changes that occur in patterns at certain intervals |
| Metals | 85% of all known elements, located on left side of periodic table, solid at room temp. with some exceptions (mercury) |
| Non-metals | Located on the right side of the periodic table, can be all three phases at room temperature |
| Metalloids | Located on the bondary between metals and non-metals on the periodic table, has a mix of both metallic and non-metallic properties, 6 commonly accepted ones: |
| alkali metals | Group 1, very reactive, useful in making soaps |
| alkali-earth metals | Group 2, form alkaline solutions, but are fire resistant, named by medieval scientists |
| Halogens | Group 17, salt forming because they form compounds known as salts |
| Noble gases | group 18, the most unreactive group |
| transition metals | groups 3-12, don't form alkaline solutions, harder and less reactive with water than alkali metals, used for structural purposes |
| periods 6 and 7 inner transition metals | no group number, each row has such similar chemical properties that they are their own group (lanthanide and actinide series) |
| lanthanide series | period 6, difficult to purify because of similar properties |
| actinide series | period 7, most famous are uranium and plutonium |
| electron shell | a distance from the nucleus where electrons may reside |
| orbitals | aka sub-shells, represent the probable position of an electron in an energy level, can only hold 2 electrons |
| 1st energy level orbitals | 1 orbital (s-orbital), can only hold 2 electrons |
| 2nd energy level orbitals | 1 s-orbital (2 electrons) and 3 p-orbitals (6 electrons) 8 total electrons |
| 3rd energy level orbitals | 1 s-orbital (2 electrons), 3 p-orbitals (6 electrons), and 5 d-orbitals (10 electrons) 18 total electrons |
| valence electrons | the outermost electrons, amount is equal to group number of the element (all elements went a full shell of eight) |
| outer electrons of metal atoms? | tend to be weakly held to the atomic nucleus the loose electrons taken off of these atoms causes metal atoms to be bonded together to form a mixture of two or more metallic elements (alloys) |
| ionic bond | the electrical force of attraction (EM force) holds a metal and non-metal together |
| ionic crystals | form from elements on opposite sides of the periodic table by ionic bonding, forms geometric shaped patterns due to the opposite charges of the ions surrounding one another |
| covalent bonds | two nonmetals atoms are attracted to SHARE electrons, both atoms nuclei are attracted to the shared electrons |
| molecules | form from non-metals that are close to one another on the periodic table that covalently |
| electron dot diagrams (aka Lewis dot) | the model of an atom in which each dot can represent a valence electron |
| ionic compound | a chemical compound made of ionically bonded ions (metal and nonmetal) |
| oxidation number | the number of electrons an atom is willing to gain or lose |
| superscripts | placed to the top of the right of the atomic symbol to indicate the magnitude and sign of an ion charge (oxidation number), positive means an atom has lost an electron/is more to the left |
| resultant vectors | the algebraic sum of two or more vectors |
| velocity vectors | the arrow length represents speed (magnitude) and shows direction |
| energy | the ability to cause change or the ability to do work |
| chemical energy | energy stored in the bonds of chemical compounds |
| electromagnetic energy | energy resulting from the flow of charged particles |
| thermal energy | energy of the moving particles of a substance |
| mechanical | energy resulting from motion |
| nuclear energy | the energy found in the nucleus of an atom |
| Kinetic energy | energy of motion, depends upon mass and speed, when either increases so does kinetic energy |
| linear kinetic energy | motion in straight lines |
| rotational kinetic energy | spinning and rotating objects |
| vibrational kinetic energy | motion due to friction and/or heat |
| wave motion kinetic energy | energy that moves in waves |
| potential energy | stored energy due to position, depends on weight and height |
| elastic potential energy | Energy stored by something that can stretch or compress |
| chemical potential energy | energy stored in the bonds of compounds |
| electrical potential energy | energy due to the position of electromagnetic particles |
| nuclear potential energy | the potential of the nucleus to undergo fission/fusion |
| gravitational potential energy | energy stored in objects based on their height above the earth's surface |
| conversion of energy | the process of changing from one energy form into another |
| Law of Conservation of Energy | states that energy cannot be created or destroyed, only change forms |
| heat | the flow of thermal energy as it transfers from one object to another (high to low temp) |
| heat-transfer conduction | the process by which heat energy is transmitted through direct contact between neighboring atoms or molecules |
| conductors | substances that are good at transferring heat by conduction |
| insulators | bad conductors (not good at transferring heat) |
| convection | the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity, which consequently results in transfer of heat |
| Radiation | a method that allows energy transfer without matter by simply moving as a particle or wave (radiant energy) |
| Calorie | (cal) the amount of heat required to change the temperature of 1 gram of water |
| specific heat capacity | the capacity of a substance to store thermal energy, |
| high heat capacity | slow rise in temperature, slow drop in temperature (water) |
| low heat capacity | quick rise in temperature, quick drop in temperature (metal) |
| temperature | quantity that tells how warm or cold an object is with respect to some scale |
| thermometer | uses the principle of expansion and contraction of a liquid to measure temperature (usually mercury or red alcohol) |
| celsius | the most common temperature measuring scale, uses a scale of 100 degrees between boiling and freezing water |
| farenheit | the temperature measuring scale used in the US, uses a scale of 180 degrees between boiling and freezing water |
| absolute zero | the lower limit of temperature, the point where no more energy can be extracted from a substance, molecules are stationary |
| Laws of Thermodynamics | 1. Energy is conserved, 2. Heat flows from hot to cold unless work is done on the system 3. Can NOT reach absolute zero |
| buffers | weak acids/ bases that prevent sudden changes in pH, needed to sustain life |
| chemical equation | A written representation of a chemical reaction |
| chemical reactions | produces new material by rearranging atom |
| reactants | materials located on the left side of an equation |
| products | newly formed materials on the right side of an equation |
| coefficents | numbers in front of chemical formulas to show how many of each |
| atomic and molecular formulas | represents products and reactants |
| symbols in a chemical equation and their meanings? | + = added to, -> = yields, upwards arrow = given off as a gas |
| Law of Conservation of Mass | Mass is neither created nor destroyed, only changes form |
| Balanced equation | atoms must appear on both sides of equation the same number of times |
| chemical | a substance that has a defined composition |
| polyatomic ion | an ion that has more than one atom |
| exothermic reaction | involves the release of energy in the form of heat or light |
| endothermic reaction | a reaction that absorbs heat |
| Equilibrium | state where forces are balanced |
| acids | compounds that form a lot of hydrogen ions (H+) when dissolved in water |
| bases | compounds that form a lot of OH- ions in water |
| pH | a quantitive measure of the amount of H+ is in a solution and can determine if something is an acid, base, or neutral |
| 1-6 pH | acid |
| 8-14 pH | basic/alkaline, high pH = lower base, very few H+ ions |
| 7 pH | neutral |
| indicators | changes color in the presence of an acid or base |
| neutralization | acid and base react and H+ combines with OH- to form water, the leftover parts form salt and properties of the acid and base disappear |
| composition (synthesis) | simple molecules join to form a more complex molecule |
| decomposition | larger molecules break down to form simplier molecules |
| single replacement | a COMPOUND mixes with an ELEMENT and the element replaces one of the substances in the compound |
| double replacement | TWO COMPOUNDS mix and exchange elements |
| combustion | A substance combines with OXYGEN (O), these reactions always produce energy in the form of heat and light and one or more of the products contain the elements in the reactants |
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