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Chemical Reactions: A World of Reactions Science Object
Science Object
Chemical Reactions: A World of Reactions
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Chemical Reactions SciPack. It explains that chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. An enormous variety of biological, chemical, and physical phenomena can be explained by changes...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Chemical Reactions SciPack. It explains that chemical reactions occur all around us, for example in health care, cooking, cosmetics, and automobiles. An enormous variety of biological, chemical, and physical phenomena can be explained by changes in the arrangement and motion of atoms and molecules. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Atoms form bonds to other atoms by transferring or sharing electrons. Carbon atoms can bond to one another in chains, rings, and branching networks to form a variety of structures, and complex chemical reactions involving these molecules take place constantly in every cell in living objects.
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Cells and Chemical Reactions: Reaction Rates in Cells Science Object
Science Object
Cells and Chemical Reactions: Reaction Rates in Cells
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates how the reaction rates in cells can be affected by temperature, pH, hydration levels, and enzymes.

Chemical reaction rates are affected by the conditions in which they occur (or...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the last of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates how the reaction rates in cells can be affected by temperature, pH, hydration levels, and enzymes.

Chemical reaction rates are affected by the conditions in which they occur (or cannot occur). Most cells must function within a narrow range of temperature and acidity because they are part of a living system. At very low temperatures, reaction rates are too slow. High temperatures and/or extremes of acidity can irreversibly change the structure of most protein molecules. Even small changes in acidity can alter the molecules and how they interact. Hydration levels also affect chemical reactions in cells; dehydrated cells lack the solvent and substrate or substrate structure needed for chemical reactions to proceed. Both decomposition and synthesis of molecules (involving energy transfer) are made possible in cells by a large set of protein catalysts, called enzymes. Without enzymes to catalyze the chemical reactions necessary for life, the conditions (including temperature) inside of cells would slow chemical reaction rates below what is necessary to stay alive. Like other protein reactions, the effectiveness of enzymes reactions is affected by temperature and acidity.
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Chemical Reactions: Rates of Chemical Reactions Science Object
Science Object
Chemical Reactions: Rates of Chemical Reactions
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Chemical Reactions SciPack. It demonstrates how chemical reactions can take place in time periods ranging from the few femto-seconds (10-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Chemical Reactions SciPack. It demonstrates how chemical reactions can take place in time periods ranging from the few femto-seconds (10-15 seconds) required for an atom to move a fraction of a chemical bond distance to geologic time scales of billions of years. The rate of reactions among atoms and molecules depends on how often they encounter one another, which is affected by the concentration, pressure (for gases), and temperature of the reacting substances. The configuration of atoms in a molecule determines the molecule's properties. Shapes are particularly important in determining how large molecules interact with others. Some atoms and molecules called catalysts are highly effective in accelerating chemical reactions. Chemical reactions in living systems are catalyzed by protein molecules called enzymes.
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Chemical Reactions: Categorizing Chemical Reactions Science Object
Science Object
Chemical Reactions: Categorizing Chemical Reactions
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Chemical Reactions SciPack. It provides an understanding of the idea that a large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Chemical Reactions SciPack. It provides an understanding of the idea that a large number of important reactions involve the transfer of either electrons (oxidation/reduction reactions) or hydrogen ions (acid/base reactions) between reacting ions, molecules, or atoms. In other reactions, chemical bonds are broken by heat or light to form very reactive radicals with electrons ready to form new bonds. Reactions involving these radicals control many processes such as the presence of ozone and greenhouse gases in the atmosphere, burning and processing of fossil fuels, the formation of polymers, and explosions.
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Cells and Chemical Reactions: Cellular Respiration Science Object
Science Object
Cells and Chemical Reactions: Cellular Respiration
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Cells and Chemical Reactions SciPack. It explores the process of cellular respiration in chemical reactions involved.

Non-photosynthetic organisms obtain the energy necessary for cell growth and maintenance by decomposing large...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Cells and Chemical Reactions SciPack. It explores the process of cellular respiration in chemical reactions involved.

Non-photosynthetic organisms obtain the energy necessary for cell growth and maintenance by decomposing large molecules into smaller molecules that have lower energy levels stored in their chemical bonds (thus, releasing some energy from bonds so that it can be used to do cellular work). These smaller molecules can enter or exit the cell to be synthesized into larger complex molecules necessary for growth and maintenance of the organism. Organisms unable to photosynthesize, such as animals and fungi, must take matter into their cells to provide the building blocks (chemical constituents) and energy needed for metabolism (both synthesis and decomposition processes). The matter and energy that is stored in the structures that are synthesized by photosynthetic organisms (for example, the stems, roots and leaves of plants) can be consumed and used by other organisms as an essential source of this matter and energy.

The chemical bonds in the molecules that are synthesized through photosynthesis and other synthesis processes contain energy that is needed by all cells (including plant cells). The energy stored in chemical bonds of the matter taken into the cells can be released and transferred into a form available for cellular work. This occurs when the bonds are broken through decomposition reactions and new compounds with lower energy bonds are formed. Cells capture some of the energy that is released during decomposition and usually store this energy temporarily in the phosphate bonds of a small high-energy compound called ATP. The energy stored in the bonds of ATP is then readily available for use by the cell for synthesis and other cellular work.
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Atomic Structure: Energy in Atoms Science Object
Science Object
Atomic Structure: Energy in Atoms
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Atomic Structure SciPack. It investigates the forces at work within the nuclei of atoms and the energy contained in within atomic nuclei. Scientists continue to investigate atoms and have discovered even smaller constituents of which neutrons...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of three Science Objects in the Atomic Structure SciPack. It investigates the forces at work within the nuclei of atoms and the energy contained in within atomic nuclei. Scientists continue to investigate atoms and have discovered even smaller constituents of which neutrons and protons are made. The nuclear forces that hold the nucleus of an atom together, at nuclear distances, are almost always stronger than the electric forces that would make it fly apart. Nuclear reactions convert a fraction of the mass of interacting particles into energy, and they can release much greater amounts of energy than interactions between atoms. Fission is the splitting of a large nucleus into smaller pieces. Fusion is the joining of two nuclei at extremely high temperature and pressure, and is the process responsible for the energy of the sun and other stars. Energy is released whenever the nuclei of very heavy atoms, such as uranium or plutonium, split into middleweight ones, or when very light nuclei, such as those of hydrogen and helium, combine into heavier ones.
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Atomic Structure: Properties of Atoms Science Object
Science Object
Atomic Structure: Properties of Atoms
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Atomic Structure SciPack. It explores the structure-related properties that make one type of atom different from another, and looks more closely at the role of the neutron. The number of protons in the nucleus determines what an atom's electron...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of three Science Objects in the Atomic Structure SciPack. It explores the structure-related properties that make one type of atom different from another, and looks more closely at the role of the neutron. The number of protons in the nucleus determines what an atom's electron configuration can be and so defines the element and its properties. An atom's electron configuration, particularly the outermost electrons, determines how the atom can interact with other atoms. Although neutrons have little effect on how an atom interacts with others, they do affect the mass and stability of the nucleus. The nucleus of radioactive isotopes is unstable and spontaneously decays, emitting particles and/or electromagnetic radiation. It cannot be predicted exactly when, if ever, an unstable nucleus will decay, but a large group of identical nuclei decay at a predictable rate. This predictability of decay rate allows radioactivity to be used for estimating the age of materials that contain radioactive substances.
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Cells and Chemical Reactions: Photosynthesis Science Object
Science Object
Cells and Chemical Reactions: Photosynthesis
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates the process of photosynthesis and the chemical reactions that take place in plant cells.

Photosynthesis involves unique synthesis chemical reactions in which energy from the...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the second of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates the process of photosynthesis and the chemical reactions that take place in plant cells.

Photosynthesis involves unique synthesis chemical reactions in which energy from the sun is transferred into energy in the chemical bonds that are formed when smaller molecules are combined to synthesize complex molecules. For nearly every living organism on Earth, the energy required by its cells originally comes from the sun and the only way to transfer light energy into living systems is through photosynthesis. Only those organisms with chlorophyll, such as plants, can capture energy by absorbing light and using it to form strong (covalent) chemical bonds between atoms of carbon-containing (organic) molecules through photosynthesis. Plants have chlorophyll contained in chloroplasts (the site of photosynthesis) where energy rich organic compounds are synthesized for use by the plant as a source of matter and energy necessary for life. This process of photosynthesis provides a vital connection between the sun and the energy needs of nearly all living systems, and also releases oxygen to the environment.

The simple carbohydrates produced during photosynthesis can be decomposed immediately to supply matter and energy needed for metabolic processes by plants or other photosynthesizing organisms. In addition, the energy from the decomposition can be used to build other complex carbon-based molecules that help the plant grow and function (including proteins, lipids and more complex carbohydrates).
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Cells and Chemical Reactions: Basics of Metabolism Science Object
Science Object
Cells and Chemical Reactions: Basics of Metabolism
Grade Level: Elementary School, High School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates the basics of cellular metabolisms in plants and animals.

Chemical reactions occur in all cells, are fundamental to cell functions, and are essential to maintain the chemical...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the first of four Science Objects in the Cells and Chemical Reactions SciPack. It investigates the basics of cellular metabolisms in plants and animals.

Chemical reactions occur in all cells, are fundamental to cell functions, and are essential to maintain the chemical and physical organization of living systems. All living organisms engage in metabolic processes that take place inside their cells. Metabolism refers to all of the chemical activities and reactions in cells and organisms that are necessary for life. Metabolic processes can be categorized into two types, which are distinguished by their function in growth and maintenance of living cells: synthesis, chemical reactions that use energy to synthesize large and complex carbon-based molecules from smaller molecules; decomposition, chemical reactions that release energy from chemical bonds by decomposing the large molecules into smaller, simpler and lower-energy molecules. The energy released in decomposition is used to synthesize large molecules and in other cellular work, including: movement, maintenance and organization, transport of molecules, and transmission of nerve impulses. A large set of protein catalysts, called enzymes are required for both synthesis and decomposition chemical reactions. Because all matter tends toward disorganized states, constant input of energy is required by all cells to maintain chemical and physical organization. Without this organization, cells and organisms die, and with death (the cessation of energy input) living systems rapidly disintegrate.
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Chemical Reactions: Matter and Energy in Reactions Science Object
Science Object
Chemical Reactions: Matter and Energy in Reactions
Grade Level: Elementary School, Middle School
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the final of four Science Objects in the Chemical Reactions SciPack. It explains how different configurations of atoms and molecules are associated with different energy levels. Some changes of configuration among atoms and molecules require a net input of energy whereas others cause...  [view full summary]
Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the final of four Science Objects in the Chemical Reactions SciPack. It explains how different configurations of atoms and molecules are associated with different energy levels. Some changes of configuration among atoms and molecules require a net input of energy whereas others cause a net release. As a result, chemical reactions may release or consume energy. Some reactions such as the burning of fossil fuels release large amounts of energy by losing heat and by emitting light. Energy from light and other electromagnetic radiation can initiate many chemical reactions such as photosynthesis and the evolution of urban smog. The behavior of atoms in chemical reactions demonstrates the conservation of matter: When the number of atoms in a closed system stays the same, their total mass remains constant no matter how they are rearranged.
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