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Name___________________________ Date_____________ Period______ Key Terms and Definitions for Physical Science, 2014-2015 Chp 1, 13, 14, 11, 12, 2, 8, 9, 3, 4, 5, 6 and 7 Chp 1-1 1. Science – the knowledge obtained by observing natural events and conditions in order to discover facts and formulate laws or principles that can be verified or tested. Science is observing, studying and experimenting to find the nature of things. It is how we discover how things work in the natural world. 2. Technology – is the application of science for practical uses or purposes. Advances in science and technology depend on one another. 3. Law – a statement or equation that accurately describes a natural process. Laws allow predictions to be made about how a system will behave. 4. Theory – is a system of ideas that explains many related observations. Theories explain WHY something happens and is supported by a wide body of evidence acquired through scientific investigation. Chp 1-2 5. Scientific method – a series of steps followed to solve problems including collecting data, formulating a hypothesis, testing the hypothesis and stating conclusions. This method helps to organize your thinking about questions. 6. Variable - a factor that changes in an experiment in order to test a hypothesis. Variables can affect the outcome of an experiment. 7. Mass – a measure of the amount of matter in an object. It is measured in grams with a triple beam balance. 8. Weight – a measure of the gravitational force exerted on an object. It is measured in g/cm3 or Newtons (N). 9. Length – a measure of the straight-line distance between two points. Length is measured in meters with a metric ruler. 10. Volume – a measure of the size of a body or region in three-dimensional space. Volume tells you how much space an object is taking up. It is measured with a graduated cylinder in mL or cm3. Chp 1-3 11. Precision – is the exactness of a measurement. For example 3.1 is less precise than 3.14159265358979323846264338327950288419716939 12. Accuracy – a description of how close a measurement is to the true value of the quantity measured. Often in science, multiple trials are done and an average is taken to improve accuracy. Page 1 of 11 Chp 13-3 13. Energy – The capacity to do work 14. Potential Energy – The energy and object has because of the position, shape or condition of the object 15. Kinetic Energy – the energy of an object due to the object’s motion. 16. Mechanical Energy – the amount of work and object can do because of the object’s kinetic and potential energies. Chp 13-4 17. Law of Conservation of Energy – Energy cannot be created or destroyed. Chp 14-1 18. Temperature – a measure of how hot or cold some is. Specifically, a measure of the average kinetic energy of the particles in an object. 19. Thermometer – an instrument that measures and indicates temperature. 20. Absolute Zero – the temperature at which molecular energy is at a minimum. (0 K or -273.16 C) Chp 14-2 21. Thermal Conduction – The transfer of energy as heat through a material 22. Convection – the movement of matter due to differences in density that are caused by temperature variations. 23. Convection Current – the vertical movement of air currents due to temperature variations Chp 11-1 24. Motion – an object’s change in position relative to a reference point. 25. Frame of reference –Objects that stay in place and are used for comparison of motion of other objects. The frame of reference objects are treated as if they are not moving. 26. Displacement – the change in position of an object. It is a measure of the straight-line distance from a starting point to an ending point. 27. Speed – the distance traveled divided by the time interval during which the motion occurred. 28. Velocity – the speed of an object in a particular direction. Chp 11-2 29. Acceleration – the rate at which velocity changes over time; an object accelerates if its speed, direction or both change. Page 2 of 11 Chp 11-3 30. Force – an action exerted on an object in order to change the object’s state of rest or motion. Forces have a magnitude (size) and a direction. 31. Friction – a force that opposes motion between two surfaces that are in contact. 32. Static friction – the force that resists the initiation of sliding motion between two surfaces that are in contact and at rest. 33. Kinetic friction – the force that opposes the movement of two surfaces that are in contact and are moving over each other. Chp 12-1 34. Inertia – the tendency of an object to resist a change in motion unless an outside net force acts on the object. Chp 12-2 35. Weight – a measure of the gravitational force exerted on an object. 36. Free fall – the motion of a body when only the force of gravity is acting on the body. 37. Terminal velocity – the constant velocity of a falling object when the force of air resistance is equal in magnitude (size) and opposite in direction to the force of gravity. 38. Projectile motion – the curved path that an object follows when thrown, launched, or otherwise projected near the surface of Earth. Chp 12-3 39. Momentum – a quantity defined as the product of the mass and velocity of an object. Chp 2-1 40. Matter – anything that has matter and takes up space. 41. Element – a substance that cannot be broken down or separated into simpler substances by chemical means. 42. Atom – the smallest unit of an element that maintains the chemical properties of that element. 43. Molecule – a group of atoms that are held together by chemical forces. A molecule is the smallest unit of matter that can exist by itself and retain all of the substances chemical properties. Molecules are combined in definite ratios. Example: a molecule of sugar is C6H12O6. 44. Compound – a substance made up of atoms of two or more different elements joined by chemical bonds 45. Pure substance – a sample of matter (either a single element or compound) that has definite chemical and physical properties. Page 3 of 11 46. Mixture – a combination of two or more substances that are not chemically combined. Chp 2-2 47. Melting point – the temperature (and pressure) that a solid becomes a liquid. 48. Boiling point – the temperature (and pressure) that a liquid becomes a gas. 49. Density – the ratio of the mass of a substance to the volume of the substance. 50. Reactivity – the capacity of a substance to combine chemically with another substance. Chp 2-3 51. Physical change – a change of matter from one form to another without a change in chemical properties. 52. Chemical change – a change that occurs when one or more substances change into entirely new substances with different properties. Chp 8-1 53. Suspension – a mixture in which particles of a material are more or less evenly dispersed throughout a liquid or gas but settle out when the mixture is allowed to stand. Solute particles are relatively large and it may be possible to filter them. 54. Colloid – a mixture consisting of tiny particles that are intermediate in size between those in solutions and those in suspensions. The tiny particles remain suspended and cannot be filtered. These particles cause the Tyndall effect, which scatters light. 55. Emulsion – any mixture of two or more immiscible liquids in which one liquid is dispersed in the other (using an emulsifier) 56. Solution – a homogeneous mixture throughout which two or more substances are uniformly dispersed. The very tiny particles dissolve and stay mixed. 57. Solute – in a solution, the substance that dissolves in the solvent. 58. Solvent – in a solution, the substance in which the solute dissolves. 59. Alloy – a solid or liquid mixture of two or more metals. The properties of the alloy are a combination of the properties of the 2 or more metals. Chp 8-2 60. Polar – describes a molecule in which the partial positive and negative charges are separated. (not as strong as an ionic charge). Caused by unequal sharing of electrons. Page 4 of 11 61. Nonpolar – describes a molecule in which the centers of positive and negative charges are not separated. There is equal sharing of electrons and these electrons are distributed evenly over the whole molecule. 62. Hydrogen bond – an intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule. Chp 8-3 63. Solubility – the ability of one substance to dissolve in another at a given temperature and pressure. 64. Concentration – the amount of a particular substance that is dissolved in a given volume of solution. 65. Saturated solution – a solution that cannot dissolve any more solute under the given conditions. 66. Unsaturated solution – a solution that contains less solute than a saturated solution does and that is able to dissolve additional solute. 67. Supersaturated solution – a solution that holds more dissolved solute than is required to reach equilibrium. It is highly unstable. 68. Molarity – a concentration unit of a solution expressed in moles of solute dissolved per liter of solution. Chp 9-1 69. Acid – any compound that increases the number of hydronium ions (H 3O+) when dissolved in water. 70. Indicator – a compound that can reversibly change color depending on conditions such as pH. 71. Electrolyte – a substance that dissolves in water to give a solution that conducts an electric current. 72. Base – any compound that increases the number of hydroxide ions (OH-) when dissolved in water. 73. pH - a value that is used to express acidity and basicity (alkalinity) of a system; each whole number on the scale indicates a tenfold change in acidity. Chp 9-2 74. neutralization reaction – the reaction of the ions that characterizes acids and the ions that characterize bases to form water molecules and a salt. 75. Salt – an ionic compound that forms when a metal atom (or a positive radical) replaces the hydrogen of an acid. When a salt is soluble in water, the ions stay separated in solution until the water evaporates. Page 5 of 11 Chp 3-1 76. Fluid – a nonsolid state of matter (liquid or gas) in which the atoms or molecules are free to move past one another. 77. Plasma – a 4th state of matter that consists of free-moving ions and electrons. Plasmas have a variable shape and volume and can conduct electricity. 78. Energy – the capacity to do work. Energy is the ability to change or move matter and can take many different forms. 79. Temperature – how hot or cold something is. It is a measure of the average kinetic energy of the particles in an object. 80. Thermal energy – The total kinetic energy of a substance’s atoms. The more atoms, the more thermal energy something has. Chp 3-2 81. Evaporation – the change in state from liquid to gas. 82. Boiling - is evaporation that occurs throughout a liquid at a certain temperature and pressure. 83. Sublimation – the process of a solid changing directly into a gas (without a liquid phase). 84. Condensation –the change in state from a gas into a liquid. 85. Melting - change in state from a solid to a liquid. 86. Freezing/solidify – change in state from a liquid to a solid. Chp 3-4 87. Gas laws – the laws that state the mathematical relationships between volume, temperature, pressure, and quantity of a gas. Chp 4-1 88. Electron – a subatomic particle that has a negative charge -1. Located in energy levels outside of the nucleus. 89. Nucleus – An atom’s central region, which is made up of protons and neutrons. Almost all of the atom’s mass is in the small, positively-charged, densely-packed nucleus. Chp 4-2 90. Proton – a subatomic particle that has a positive charge and that is located in the nucleus of an atom. Each proton has a charge of +1. 91. Neutron – a subatomic particle that has no charge (0) and that is located in the nucleus of an atom. 92. Atomic number – the number of protons in the nucleus of an atom. 93. Mass number – the sum of the number of protons and neutrons in the nucleus of an atom. (always a whole number) Page 6 of 11 94. Isotope – an atom that has the same number of protons (and same atomic number) but has a different number of neutrons (and thus a different mass number). 95. Atomic mass unit – unit of mass for an atom or molecule. Symbol is u. It is 1/12th the mass of a carbon-12 atom. 96. Mole – the SI base unit used to measure the AMOUNT of a substance whose number of particles is the same as the number of atoms of carbon in exactly 12 g of carbon-12. Specifically, a mole is 6.022 x 1023 particles of anything. Chp 4-3 97. Orbital – a region in an atom where there is a high probability of finding electrons. 98. Valence electron – an electron that is found in the outermost energy level of an atom and that determines the chemical properties of an atom. 99. Photon – a unit or quantum of light. (like a packet of energy) Chp 5-1 100. Periodic law – the law states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements. 101. Period – horizontal row (across) of elements on the periodic table. There are 7 periods currently. 102. Group – a vertical column (up and down) of elements in the periodic table. There are 18 groups currently. Elements in a group share chemical properties. Chp 5-2 103. Ion – an atom, radical or molecule that has lost or gained one or more electrons and has a negative or positive charge. 104. Metal – an element that is shiny, conducts (carries) heat and electricity well. Metals are often malleable (bendable) and ductile (can be pulled into wires). Mostly solids (2 liquids at room temp) 105. Nonmetal – an element that cannot conduct heat or electricity well. Are often dull and brittle and can be solids, liquids or gases. 106. Semiconductor – an element or compound that conducts electric current better than an insulator does but not as well as a conductor does. Located on “staircase” on periodic table. Chp 5-3 107. Alkali metal – elements in group 1. Highly reactive, soft solids. 108. Alkaline earth metal – elements in group 2. Less reactive than group 1, harder denser and stronger. Page 7 of 11 109. Transition metal – elements in groups 3-12. Some are less reactive, can form many cations, fill inner energy levels before outer, most are hard, dense and have high melting points except for mercury (liquid at room temp). 110. Halogen – elements in group 17. Most reactive non-metals. 111. Noble gas – elements in group 18. Are non-reactive gasses (inert) that exist as single atoms not compounds. Chp 6-1 112. Chemical bond – the attractive force that holds atoms or ions together. 113. Chemical structure – the arrangement of atoms in a substance. 114. Bond length – the average distance between the nuclei of two bonded atoms. 115. Bond angle – the angle formed by two bonds to the same atom. Chp 6-2 116. Ionic bond – the attractive force between oppositely charged ions, which form when electrons are transferred from one atom to another. 117. Covalent bond – a bond that is formed when atoms share one or more pairs of electrons. Polar covalent bonds do not share electrons equally. Nonpolar covalent bonds do share electrons equally. 118. Metallic bond – a bond formed by the attraction between positively charged metal ions and the electrons around them. 119. Polyatomic ion – an ion made of two or more atoms.-3 Chp 6-3 120. Empirical formula – the composition of a compound in terms of the relative numbers and kinds of atoms in the simplest ratio. 121. Molecular formula – a chemical formula that shows the number and kinds of atoms in a molecule, but not the arrangement of atoms. Chp 6-4 122. Organic compound – a covalently bonded compound that contains carbon, excluding carbonates and oxides. 123. Polymer – a large molecule that is formed by more than 5 monomers, or small units. 124. Carbohydrate – a class of molecules that includes sugars, starches, and fiber; contains carbon, hydrogen and oxygen. 125. Protein – an organic compound that is made of one or more chains of amino acids and that is a principal component of all cells. 126. Amino acid – a compound of a class of simple organic compounds that contain a carboxyl group and an amino acid group and that combine to form proteins. Page 8 of 11 Chp 7-1 127. Reactant – a substance or molecule that participates in a chemical reaction. 128. Product – a substance that forms in a chemical reaction. 129. Chemical energy – the energy released when a chemical compound reacts to produce new compounds. 130. Endothermic reaction – a chemical reaction that requires energy input. 131. Exothermic reaction – a chemical reaction in which energy is released to the surroundings as heat. Chp 7-2 132. Chemical equation – a representation of a chemical reaction that uses symbols to show the relationship between the reactants and products. 133. Mole ratio – the relative number of moles of the substances required to produce a given amount of product in a chemical reaction. Chp 7-3 134. Synthesis reaction – reaction in which two or more substances combine to form a new compound. 135. Decomposition reaction – a reaction in which a single compound breaks down to form two or more simpler substances. 136. Combustion reaction – the oxidation reaction of an organic compound, in which heat is released. Carbon dioxide and water are products. 137. Single-displacement (replacement) reaction – a reaction in which one element or radical takes the place of another element or radical in a compound. 138. Double – displacement (replacement) reaction – a reaction in which two compounds exchange atoms or ions. Products are a precipitate, a gas or a solid. 139. Oxidation-reduction (redox) reaction – any chemical change in which one substance is oxidized (loses electrons) and one substance is reduced (gains electrons). Chp 7-4 140. Catalyst – A substance that changes the rate of a chemical reaction without being consumed or changed significantly. 141. Enzyme – a molecule, either protein or DNA, that acts as a catalyst in biochemical reactions (in living things). 142. Substrate – the reactant in reactions catalyzed by enzymes. 143. Chemical equilibrium – a state of balance in which the rate of a forward reaction equals the rate of the reverse reaction. The concentration of products and reactants remains unchanged. Page 9 of 11 Physical Science Formulas Chp 13 Gravitational Potential Energy = Mass x Free-Fall Acceleration x Height grav PE = mgh Kinetic Energy Equation = ½ x mass x speed squared KE = ½ mv2 Chp 14 Fahrenheit temperature = (1.8 x Celsius temperature) + 32 TF = 1.8 TC + 32 Celsius temperature = (Fahrenheit temperature – 32) / 1.8 TC = (TF – 32) / 1.8 Kelvin Temperature = Celsius Temperature + 273 TK = TC + 273 Specific Heat Equation: Energy = specific heat x mass x temperature change Energy = cm∆T Chp 11 average speed = distance / time v = d/t velocity = distance / time including direction v = d / t with direction slope = vertical change / horizontal change acceleration = (final velocity – initial velocity) / time a = (VF – Vi) / t Page 10 of 11 Chp 12 Force = mass x acceleration f = ma weight = mass x free fall acceleration w = mg momentum = mass x velocity p = mv Chp 2 Density = mass / volume D = m/V Chp 8 Molarity = moles of solute / liters of solution M = mol / L Chp 3 Gas Laws: Boyle Increase Pressure = Decrease Volume, with Constant Temperature Gay-Lussac Increase Temperature = Increase Pressure, with Constant Volume Charles Increase Temperature = Increase Volume, with Constant Pressure Chp 4 Amount (mol) = molar mass / 1 mol = Mass (g) Mass (g) = 1 mol / molar mass = Amount (mol) Page 11 of 11