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| Frage | Antworten |
| buffer | solution that is resistant to large changes in pH |
| electrolyte | compound that produces ions when it dissolves |
| pH | measure of the hydronium ion concentration of a solution |
| base | compounds that produce hydroxide ions when dissolved in water |
| exothermic | reaction that releases energy to its surroudings |
| saturated | solution that contains as much solute as the solvent can normally hold at a given temperature |
| acid | compounds that produce hydronium ions when dissolved in water |
| solubility | max amount of solute that normally dissolves in a given amount of solvent at a certain temperature |
| molarity | number of moles of a dissolved solute per liter of solution |
| equilibrium | the forward and reverse paths of a chemical change take place at the same rate |
| reaction rate | rate at which reactants change into products over time |
| science | a system of knowledge and the methods you use to find that knowledge |
| technology | use of knowledge to solve practical problems |
| How does the process of science start and end? | Science begins with curiosity and often ends with discovery |
| What is the relationship between science and technology? | Science and technology are interdependent. Advances in one lead to advances in the other |
| What are the branches of natural science? | Natural science is generally divided into three branches: physical science, earth and space science, and life science |
| Chemistry | study of the composition, structure, properties, and reactions of matter |
| physics | study of matter and energy and the interactions between the two through forces and motion |
| geology | (foundation of earth science) study of the origin, history, and structure of earth |
| astronomy | (foundation of space science) study of the universe beyond earth, including the sun, moon, planets, and stars |
| biology | study of living things, or life science. it is not only the physics and chemistry of living things, but the study of the origin and behavior of living things |
| scientific method | an organized plan for gathering, organizing, and communication information |
| What is the goal of a scientific method? | The goal of any scientific method is to solve a problem or to better understand an observed event |
| observation | information that you obtain through your senses. repeatable observations are known as facts |
| hypothesis | a proposed answer to a question |
| manipulated variable | variable that causes a change in another |
| responding variable | variable that changes in response to the manipulated variable |
| controlled experiment | an experiment in which only one variable, the manipulated variable, is deliberately changed at a time |
| scientific theory | a well-tested explanation for set of observations or experimental results |
| scientific law | a statement that summarizes a pattern found in nature |
| How does scientific law differ from scientific theory? | A scientific law describes an observed pattern in nature without attempting to explain it. The explanation of such a pattern is provided by a scientific theory |
| model | representation of an object or event |
| Why are scientific models useful? | Scientific models make it easier to understand things that might be too difficult to observe directly |
| scientific notation | way of expressing a value as the product of a number between 1 and 10 and a power of 10 example: 3.0x10^8 = 300,000,000 |
| negative scientific notation | for numbers less than 1 that are written in scientific notation, the exponent is negative; and tells you how many decimals places there are to the left of the number 8.6x10^-4 = 0.00086 |
| Why is scientific notation useful? | Scientific notation makes very large or very small numbers easier to work with |
| What units do scientists use for their measurements? | Scientists use a set of measuring units called SI, or the International System of Units |
| length | or the straight-line distance between two points |
| Volume | the amount of space taken up by an object |
| Density | the ration of an object's mass to its volume |
| Precision | a gauge of how exact a measurement is |
| significant figures | all the digits that are known in a measurement |
| How does the precision of measurements affect the precision of scientific calculations? | The precision of a calculated answer is limited by the least precise measurement used in the calculation |
| Accuracy | the closeness of a measurement to the actual value of what is being measured |
| How do scientists organize data? | Scientists can organize their data by using data tables and graphs |
| slope | the steepness of a line, equal to the ratio of a vertical change to the corresponding horizontal change |
| conversion factor | ration of equivalent measurements that is used to convert a quantity expressed in one unit to another unit |
| direct proportion | relationship in which the ratio of two variables is constant |
| inverse proportion | relationship in which the product of two variables is a constant |
| How can scientists communicate experimental data? | Scientists can communicate results by writing in scientific journals, speaking at conferences, conversations, e-mails, and websites |
| pure substance | matter that always has exactly the same composition |
| Why does every sample of a given substance have the same properties? | Every sample of a given substance has the same properties because a substance has a fixed, uniform composition |
| element | substance that cannot be broken down into simpler substances |
| atom | smallest particle of an element |
| Explain why the composition of an element is fixed. | An element has a fixed composition because it contains only one type of atom |
| compound | substance that is made from two or more simpler substances and can be broken down into those simpler substances |
| Describe the composition of a compound. | A compound always contains two or more elements joined in a fixed proportion |
| Why can properties of a mixture vary? | The properties of a mixture can vary because the composition of a mixture is not fixed |
| heterogeneous mixture | type of mixture in which the parts of the mixture are noticeably different from one another |
| homogeneous mixture | type of mixture in which the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another |
| On what basis can mixture be classified as solutions, suspension, or colloids? | Based on the size of its largest particles, a mixture can be classified as a solution, a suspension, or a colloid |
| solution | the mixture that forms when substances dissolve and form a homogeneous mixture |
| suspension | heterogeneous mixture that separates into layers over time |
| colloid | a mixture that contains some particles that re intermediate in size between the small particles in a solution and the larger particles in a suspension |
| physical property | any characteristic of a material that can be observed or measured without changing the composition of the substances in the material |
| What are some examples of physical properties? | viscosity, conductivity, malleability, hardness, melting point, boiling point, and density are examples of physical properties |
| viscosity | the tendency of a liquid to keep from flowing - its resistance to flowing |
| conductivity | material's ability to allow heat to flow |
| malleability | the ability of a solid to be hammered without shattering |
| hardness | one way to compare the hardness of two materials is to see which of the materials can scratch the other |
| melting point | the temperature at which s substance changes from a solid to a liquid |
| boiling point | the temperature at which a substance boils |
| How can knowing the physical properties of matter be useful? | physical properties are used to ID a material, to choose a material for a specific purpose, or to separate the substances in a mixture |
| What processes are used to separate mixtures? | Filtration and distillation are two common separation methods |
| Filtration | process that separates materials based on the size of their particles |
| distillation | the process that separates the substances in a solution based on their boiling points |
| physical change | occurs when some of the properties of a material change, but the substances in the material remain the same |
| chemical Properties | ability to produce a change in the composition of matter |
| When can a chemical property by observed? | Chemical properties can be observed only when the substances in a sample of matter are changing into different substances |
| Flammability | material's ability to burn in the presence of oxygen |
| reactivity | The property that describes how readily a substance combines chemically with other substances |
| chemical change | occurs when a substance reacts and forms one or more new substances |
| What observations may indicate that a chemical change has occurred? | Three common types of evidence for chemical change are a change in color, the production of a gas, and the formation of a precipitate. |
| precipitate | any solid that forms and separates from a liquid mixture |
| What is the difference between chemical and physical changes? | When matter undergoes a chemical change, the composition of the matter changes. When matter undergoes a physical change, the composition of the matter remains the same |
| How can shape and volume be used to classify materials? | Materials can be classified as solids, liquids, or gases based on whether their shapes and volumes are definite or variable |
| Solid | state of matter in which materials have a definite shape and a definite volume |
| Liquid | state of matter in which a material has a definite volume but not a definite shape |
| Gas | state of matter in which a material has neither a definite shape nor a definite volume |
| Kinetic energy | energy an object has due to its motion |
| How can kinetic theory and forces of attraction be used to explain the behavior of gases, liquids, and solids? | The kinetic theory of matter says that all particles of matter are in constant motion |
| How is a gas able to fill a container of any size or shape? | The constant motion of particles in gas allows a gas to fill a container of any shape or size |
| Use kinetic theory and attractive forces to explain why a liquid has a definite volume and a shape that can vary. | A liquid takes the shape of its container because particles in a liquid can flow to new locations, The volume of a liquid is constant because the forces of attraction keep the particles close together |
| Explain why a solid has a definite shape and volume | Solids have a definite volume and shape because particles in a solid vibrate around fixed locations |
| The kinetic theory three main points are? | particles in a gas are in constant, random motion. The motion of one particle is unaffected by the motion of other particles unless the particles collide. Forces of attraction among particles in a gas can be ignored under ordinary conditions. |
| Pressure | result of a force distributed over an area. |
| How does the frequency of collisions affect the pressure of a gas? | Collisions between particles of a gas and the walls of the container cause the pressure in a closed container of gas. |
| What factors affect gas pressure? | Factors that affect the pressure of an enclosed gas are its temperature, its volume, and the number of its particles |
| How does increasing the temperature affect the pressure of a contained gas? | Raising the temperature of a gas will increase its pressure if the volume of the gas and the number of particles are constant |
| What happens to the pressure of a gas if its volume is reduced? | Reducing the volume of a gas increases its pressure if the temperature of the gas and the number of particles are constant |
| How does increasing the number of particles of a contained gas affect its pressure? | Increasing the number of particles will increase the pressure of a gas if the temperature and the volume are constant |
| absolute zero | A temperature of 0 K |
| Charles Law | states that the volume of a gas is directly proportional to its temperature in Kelvins if the pressure and the number of particles of the gas are constant |
| Boyle's Law | states that the volume of a gas is inversely proportional to its pressure if the temperature and the number of particles are constant |
| Combined law | describes the relationship among the temperature, volume, and pressure of a gas when the number of particles is constant |
| phase change | reversible physical change that occurs when a substance changes from one state of matter to another |
| What are six common phase changes? | Melting, freezing, vaporization, condensation, sublimation, and deposition are six common phase changes |
| endothermic change | the system absorbs energy from its surroundings |
| exothermic change | the system releases energy to its surroundings |
| vaporization | the phase change in which a substance changes from a liquid into a gas |
| evaporation | process that changes a substance from a liquid to a gas at temperature below the substance's boiling point |
| vapor pressure | the pressure caused by the collisions of the vapor and the walls of the container |
| condensation | phase change in which a substance changes from a gas or vapor to a liquid |
| Sublimation | phase change in which a substance changes from a solid to a gas or vapor without changing to a liquid first |
| deposition | When a gas or vapor changes directly into a solid without first changing into a liquid |
| What happens to a substance's temperature and a system's energy during a phase change? | The temperature of a substance does not change during a phase change. Energy is either absorbed or released during a phase change. |
| What happens to the arrangement of water molecules as water melts and freezes? | The arrangement of molecules in water becomes less orderly as water melts and more orderly as water freezes |
| What is the difference between evaporation and boiling? | Evaporation takes place at the surface of a liquid and occurs as temperatures below the boiling point |
| What was Dalton's theory of the structure of matter? | Dalton proposed the theory that all matter is made up of individual particles called atoms, which cannot be divided |
| what are the 4 main points of Dalton's theory | All elements are composed of atoms. all atoms of the same element have the same mass, and atoms of different elements have different masses. Compounds contain atoms of more than one element. In a particular compound, atoms of different elements always combine in the same way. |
| nucleus | a dense, positively charged mass located in the center of the atom |
| What evidence did J.J Thomson provide about the structure of an atom? | Thomson's experiments provided the first evidence that atoms are made of even smaller particles |
| What did Rutherford discover about the structure of an atom? | According to Rutherford's model, all of an atom's positive charge is concentrated in its nucleus |
| What are three subatomic particles? | Protons, electrons, and neutrons |
| proton | (+) charged subatomic particle that is found in the nucleus of an atom |
| Electron | (-) charged subatomic particle that is found int he space outside of the nucleus |
| neutron | neutral subatomic particle that is found in the nucleus of an atom |
| What properties can be sued to compare protons, electrons, and neutrons? | Protons, electrons, and neutrons can be distinguished by mass, charge, and location in an atom |
| Atomic number | of an element equals the number of protons in an atom of that element |
| How are atoms of one element different form atoms of other elements? | atoms of different elements have different numbers of protons |
| mass number | of an atom is the sum of the protons and neutrons in the nucleus of that atom |
| Isotopes | are atoms of the same element that have different numbers of neutrons and different mass numbers |
| How are the isotopes of an element different from one another? | Isotopes of an element have the same atomic number but different mass numbers because the have different numbers of neutrons |
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