| A | B |
|---|
| hypothesis | What is a reasonable explanation of an observation or experimental result or a possible answer to a scientific question that can be tested? |
| may or may not be | The hypothesis ------- ---- ------- ----- ---supported by the experimental results. |
| cause and effect | Hypothesis is often started in terms of a ------- ------ --------- relationship. |
| prove | The results of an experiment cannot ------ that a hypothesis is correct. |
| support or do not support | The results -------- ---- ---- ----- --------- the hypothesis. |
| credible, accurate, relevant | Use ---------, --------------, and -------------- sources of scientific information in preparation for generating a hypothesis. |
| greater | The more decimals in the recorded measurement, the --------- the precision of the instrument. |
| precision | What is a measure of the degree to which measurements made in the same way agree with one another? |
| accuracy | The ----------- of a result is the degree to which the experimental value agrees with the true or accepted value. |
| accuracy | It is possible to have a high degree of precision with poor ------------. |
| a question | Scientific investigations are designed to answer ----------- about the relationship between two variables in a predicted "cause-effect relationship." |
| independent, dependent | The statement that predicts the relationship between an -------------- and ----------- variable is called a hypothesis. |
| independent variable | What is the variable that the experimenter deliberately changes or manipulates in an investigation? |
| dependent variable | What is the variable that changes in an investigation in response to changes in the independent variable? |
| cause, effect | The independent variable is the "-------" and the dependent variable is the "------" in the "cause-effect" relationship that is predicted. |
| controlled variables | The variables which are held constant are called ------------ -----------. |
| control group | A -------- ------ is set up as a basis of comparison to test whether the effects on the dependent variable came from the independent variable or from some other source. |
| first, right | Data should be organized in charts which list the values for the independent variable in the ------- column and list the values for the dependent variable in a column to the ------ of the independent variable. |
| line graph | What graph is used for continuous quantitative data? |
| bar graph | What graph is used for non-continuous data which is usually categorical? |
| circle graph | What graph shows a relationship among parts of a whole? |
| percentage | Circle graphs often involve ------------ data. |
| direct variation, constant, increased | A --------- ------------- is one in which, one variable increases as the other increases or as one variable decreases the other decreases. A straight line with a positive slope indicates a direct relationship that changes at a -------- rate. A greater slope indicates an ----------- rate of change. |
| inverse variation | An ----------- ------------- is one in which the product of two quantities is a constant. |
| dimensional analysis | What is used to change the units of the measurement determined, not the value of the measurement itself? |
| scientific model | What is an idealized description of how phenomena occur and how data or events are related? |
| constant | In a controlled scientific investigation, the hypothesis is a prediction about the relationship between an independent and dependent variable with all other variables being held ---------. |
| refute, verify | Results of a controlled investigation will either --------- the hypothesis or ---------- by supporting the hypothesis. |
| shape | The -------- of a graph can show the relationship between the variables in the hypothesis. |
| further | If the data does support the relationship, the hypothesis is still always tentative and subject to -------- investigation |
| scientific laws, revision | ------------ -------- express principles in science that have been tested and tested and always shown to support the same hypothesis. Even these laws, however, can be shown to need ---------- as new scientific evidence is found with improved technology, advanced scientific knowledge, and more controlled scientific investigations based on these. |
| problem identification, solution design, implementation, and evaluation | What are the four steps of technological design? |
| subatomic particles | The atom is composed of ------------ ------------ that affect the properties of an atom. |
| protons, neutrons, and electrons | What are the subatomic particles of an atom? |
| protons and neutrons | What two subatomic particles that have about the same mass? |
| less | The mass of an electron is much ------ than the mass of protons and neutrons. |
| positive, no | Protons have (a) --------- charge and neutrons have (a) -------charge. |
| positive, protons | The net charge of the nucleus is --------- and equal to the number of --------. |
| electrons | What subatomic particle has a negative charge? |
| electrons, protons | There is an attractive force between ---------- and -----------. |
| electrons, protons | There is a repulsive force between ---------- and electrons, and between ------------ and protons. |
| neutral | What is the overall charge of an atom? |
| nucleus | Protons and neutrons are tightly bound in a tiny ------------. |
| center | The nucleus is located in the ----------- of an electron cloud. |
| electron cloud | The ----------- --------- is the space where electrons are moving erratically in areas of space called energy levels. |
| energy levels | ------------ -------- are regions of space at increasing distances from the nucleus. |
| more | Electrons with -------- energy occupy energy levels further from the nucleus. |
| protons | The number of ----------- determines the identity of an atom (an element). |
| neutrons | While atoms of the same element have the same number of protons, the number of ---------- may vary. |
| element | An atom of a given element may lose or gain electrons yet it still remains the same ----------. |
| mass | Only the total number of protons and neutrons within its nucleus determines the -------- of the atom. |
| nucleus | The particles in the --------- of the atom do not change in a chemical reaction. |
| in the electron cloud | Chemical reactions occur where? |
| chemically | The number of electrons in the outer energy level of the atom and the relative distance from the nucleus of these outer-energy level electrons determine how the atom will react ------. |
| electron cloud | The volume of the ------------ --------- determines the volume of the atom. |
| atomic number, same | The ----------- ------------ of an element is equal to the number of protons. The atomic number is always the -------- for a given element. |
| can, whole number | The atomic number of an element -------- be found on the periodic table. Since it is the same for all atoms of that element, it is always a ---------- ------------. |
| neutrons | Atoms of the same element may have different numbers of ----------. |
| mass number | The ------- ----------- of a particular atom is the sum of that atom's protons and neutrons. |
| cannot | The mass number ---------- be found on the periodic table |
| atomic mass | The --------- ------- of an element is the weighted average of the masses of the naturally occurring isotopes of an element. |
| can | The atomic mass of an element --------- be found on the periodic table. |
| mass numbers | Atoms of the same element with different numbers of neutrons will have different ------ ----------. |
| isotopes | ---------- are defined as two or more atoms of the same element having the same number of protons but different numbers of neutrons (and therefore different masses). |
| neutrons | In order for a nucleus to be stable, there must be enough ------- present to block the repulsive forces among the protons. |
| radioactive | An unstable isotope of an element is -----------. |
| nuclear decay | ---------- --------- is a nuclear reaction that involves emission of energy or particles from the nucleus, resulting in a more stable nuclear environment. |
| radiation | What is the term used to describe the particles and/or energy that are emitted during nuclear decay? |
| naturally | Nuclear decay occurs ---------- in many elements that are common on earth and there is always some radiation present in every environment. |
| period | What is the term used to describe a horizontal row on the periodic table? |
| group or family | What are terms used to describe a vertical column on the periodic table? |
| metals, metalloids, and nonmetals | What are the major categories of elements on the periodic table? |
| metalloids | What are elements that have some characteristics of metals and some of nonmetals called? |
| period | The --------- in which an element appears on the periodic table indicates the number of occupied energy levels. |
| valence electrons | What is the term for the electrons in the outer-most energy level? |
| one | From left to right across periods 1-3: Atoms of all these elements contain ------- more valence electron than the atoms of the previous element. |
| valence electrons | From top to bottom within any group: Atoms of all of the elements in a given group contain the same number of ---------- -----------. |
| energy levels | From left to right across any period: Atoms of all elements in a given period have the same number of --------- --------. |
| one | From top to bottom within any group: Atoms of each subsequent element (from top to bottom) in any given group contain ------ more energy level than the atoms of the element above. |
| protons, neutrons | mass number = number of --------- + number of ------------ |
| 8 | A stable atom contains how many valence electrons? |
| gain, lose, share | Atoms that do not contain 8 valence electrons in the neutral state tend to -------, -------- or -------- valence electrons in order to achieve stability. |
| electrons | Only ------------ are involved in chemical reactions. |
| constant | In chemical reactions, the number of protons and the number of neutrons remain ------------. |
| lose | The elements in groups 1 and 2 tend to ------- 1 and 2 electrons respectively. |
| stable | The elements in group 18 are --------- and do not readily gain nor lose electrons. |
| gain | The elements in groups 16 and 17 tend to ------- 2 and 1 electron respectively. |
| elements in groups 3-12 in the periodic table | What are transition elements? |
| lose | Most of the transition elements tend to ------- electrons. |
| metals | What are the elements that tend to lose electrons? |
| non-metals | What are the elements that tend to gain electrons? |
| physical | A ------------ property of a substance is a characteristic of the substance that can be observed directly or measured with a tool without changing the composition of the substance. |
| chemical | A ------------ property is a description the capacity of a substance to undergo a change that will alter the composition of the substance. |
| measurement | The terms boiling point and melting/freezing point do not refer to the phase change itself, but to a ---------------: the temperature at which these changes occur. |
| composition, physical | The -------------- of a substance does not change during phase change nor does it change when one measures temperature in order to determine the boiling point, and freezing point/ melting point, therefore, boiling point and melting/freezing point are ------------ properties. |
| denisty | What is the term for the mass of a substance per unit volume? |
| density | The ----------- of a substance changes with a phase change because the volume of a particular substance is dependent upon phase, the density of a particular substance is as well. |
| mass, volume | Density can not be measured directly, but is the ratio of two measurements: --------- and -------------. |
| physical | Is density a physical or chemical property? |
| solubility | What is the term for the maximum amount of a solute that can dissolve in a given volume of solvent at a particular temperature and pressure. |
| solute | What is the term for the substance being dissolved? |
| solvent | What is the term for the dissolving medium? |
| solute | A saturated solution is one in which the maximum mass of the -------- is dissolved in the solvent at a particular temperature. |
| physical | The components of solutions (and therefore mixtures) do not chemically combine to form a new substance and therefore, solutions are composed of two substances which each retain their own properties. Therefore solubility is a --------- property. |
| viscosity | What is a property of fluids (focus on liquids)? |
| resistance, longer | Viscosity is a measure of the material's ------------ to flow. High-viscosity fluids take -------- to pour than low-viscosity fluids. |
| temperature | Viscosity may change with ---------------. |
| physical | The composition of a fluid does not change when it is poured and therefore, viscosity is a ----------- property. |
| electrical conductors | Materials (such as metals) with high conductivity are called ----------- ----------------- because they allow current to flow easily. |
| electrical insulators | Materials with low conductivity block current from flowing and are called ----------- --------------. |
| electrolytes | Some solutions can conduct electric current, depending on the nature of the solute. Solutes that allow electric current to flow are called what? |
| physical | Electrical conductivity is a ------------- property. |
| oxidation | When ----------- occurs, a substance combines with oxygen to form a new substance with new properties. |
| atoms | The new substance formed through oxidation is a combination of the ---------- of the original substance and oxygen. |
| corrosion | What is the term for the process by which metals naturally combine with oxygen, sulfur, or other nonmetals? |
| metal, nonmetal | when corrosion occurs, the new substance that is formed is a combination of a -------- and a ----------------. |
| carbon, hydrogen | hydrocarbons are a class of organic particles composed of various combinations of the elements, ---------- and ------------. |
| combustible | many hydrocarbons are -------------- so they are used for fuel, including gasoline, kerosene, jet fuel, and diesel oil. |
| atom | elemental substances (elements) are composed of only one type of --------. |
| atom | an ----------- is the smallest particle of matter that retains the properties of an elemental substance. |
| molecular substances | What are composed of two or more atoms covalently bonded together? |
| molecule | What is the term for the smallest particle of a molecular substance that can exist and still have the composition and chemical properties of the substance |
| elements | The chemical and physical properties of a molecular substance are different from the chemical and physical properties of the component -----------. |
| pure substances | What is the term for substances which have unique, identifying properties? |
| elements and compounds | What are the two types of pure substances? |
| element | What is the term for a pure substance which is composed of only one type of atom? |
| compound | What is the term for a pure substance which is composed of more that one type of element? |
| elements | Compounds all have identifying properties which are different from the properties of the ------------ which compose them. |
| chemical reactions | Compounds can be decomposed into elements only by ------------ -------------. |
| definite | Compounds have a ------------ chemical composition identified within a chemical formula. |
| mixture | When matter is composed of two or more component substances which retain their own identifying properties, the matter is classified as a -----------. |
| physically | A mixture can be separated ----------- because the components of the mixture have different physical properties |
| composition | Mixtures do not have definite -----------------. |
| mixtures | Procedures for separating -------------- include: dissolving, filtering, evaporating, decanting, magnetic separation, separating by particle size (screening), or chromatography |
| heterogeneous, homogeneous | What are the two groups mixtures can be classified into? |
| heterogeneous | ----------------- mixtures do not have the components distributed evenly throughout. The different components are easy to see in this mixture. |
| homogeneous | ------------------ mixtures have components evenly distributed. The components are small that they can not be seen with the naked eye. |
| solution | A ----------- is a homogeneous mixture in which the components are close to the size of individual particles of the substance (atoms, molecules, or ions) and therefore, too tiny to be seen with a microscope. |
| faster | The higher the temperature, the ---------- the rate of dissolving for a solid in a liquid. |
| rapidly | At higher temperatures the water molecules move faster and collide with the surface of the solute more often carrying off particles of the solute so dissolving occurs more -----------. |
| smaller | The ----------- the size of the particles, the faster they dissolve. |
| more | The --------- the solution is agitated, the faster the rate of dissolving for a solid in a liquid. |
| faster | When a solution is agitated, the water particles collide with the surface of the solute more frequently and the dissolving process occurs ---------. |
| soluble | If a substance is --------- in water, it will eventually dissolve even if the particle size is large, the temperature is low and there is no agitation. |
| temperature | What is a term used to describe the average kinetic energy of the particles in a substance. |
| higher | The faster particles are moving the -------- the temperature. |
| movement (energy) | Phase change is due to changing the -------------- of the particles. |
| liquid, solid | The freezing or melting point is the temperature where a phase change occurs between a --------- and a -------------. |
