The Nature of Matter and Chemical reactions and Enzymes – Flashcards
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What is an atom?
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the study of chemistry begins with the basic unit of matter
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What would you say about the appearance of an atom?
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incredibly small, an atom contains subatomic particles that are even smaller
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what are the subatomic particles that make up atoms?
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protons, neutrons, and electrons
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what are the charges of protons and neutrons?
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protons (+) and neutrons carry no charge
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What is the nucleus?
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strong forces bind protons and neutrons
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what is a negatively charged particle?
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electron
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where are the electrons?
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constant motion in the space surrounding the nucleus
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what are electrons attracted to?
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attracted to the positively charged nucleus but remain outside the nucleus because of the energy of their motion
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what makes some atoms neutral?
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atoms have equal numbers of electrons and protons and because these subatomic particles have equal but opposite charges, atoms are neutral
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what is an element?
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a pure substance that consists entirely of one type of atom
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what is the number of protons in an atom represented by?
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atomic number
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what are isotopes?
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atoms of the same elements that differ in the number of neutrons
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what is the sum of the protons and neutrons in the nucleus of an atom called?
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mass number
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how are isotopes identified?
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mass numbers
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what is the weighted average of the masses of an element's isotopes called?
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atomic mass
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what does "weighted" mean?
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the abundance of each isotope in nature is considered when the average is calculated
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what does it mean for all isotopes when they have the same number of electrons?
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the same chemical properties
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what does it mean that isotopes are radioactive?
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their nuclei are unstable and break down at a constant rate over time
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List different ways how radioactive isotopes can have important scientific d practical uses
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geologists can determine the ages of rocks and fossils by analyzing the isotopes found in them. radiation from certain isotopes can be used to treat cancer and to kill bacteria that cause food to spoil. It can also be used as labels or tracers to follow the movements of substances within organisms.
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what is a compound
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a substance formed by the chemical combination of two or more elements in definite proportions
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how do scientists show the composition of compounds?
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chemical formula
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how can a compound differ from the elements that they are made from?
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physical and chemical properties can be different
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how are atoms in compounds held together?
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chemical bonds
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what are electrons that are available to form bonds called?
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valence electrons
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what are the main types of chemical bonds?
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ionic bonds and covalent bonds
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what is an ionic bond?
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formed when one or more electrons are transferred from one atom to another
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what are ions?
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positively and negatively charged atoms
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what forms when electrons are shared between atoms?
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covalent bond
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what is the molecule?
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the structure that results when atoms are joined together by covalent bonds. the smallest unit of most compounds
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Explain van der Waals forces
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when molecules are close together, a slight attraction can develop between the oppositely charged regions of nearby molecules. chemist called such intermolecular forces of attraction van der waals forces, after the scientist who discovered them. not as strong as ionic bonds or covalent bonds, they can hold molecules together especially when the molecules are large
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what is a chemical reaction?
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a process that changes, or transforms, one set of chemicals into another
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what is an important scientific principle?
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mass and energy are conserved during chemical transformatinons
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what are reactants?
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elements or compounds that enter into a chemical reaction
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what are products?
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elements or compounds produced by a chemical reaction
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chemical reactions always involve in what changes?
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changes in the chemical bonds that join atoms in compounds
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what is one example of an important chemical reaction that occurs in your body?
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carbon dioxide
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where is the carbon dioxide carried to in your body?
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lungs through the bloodstream, and not very soluble in water. the bloodstream could not possibly dissolve enough carbon dioxide to carry it away from your tissues were it not for a chemical reaction. as it enters the blood, carbon dioxide reacts with water to produce a highly soluble compound called carbonic acid.
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what is released or absorbed whenever chemical bonds form or are broken?
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energy
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because chemical reactions involve breaking and forming bonds, they involve changes in what?
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energy
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what is one of the most important factors in determining whether a chemical reaction will occur?
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energy changes
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what could say about chemical reactions that release or absorb energy?
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chemical reactions that release energy often occur spontaneously. chemical reactions that absorb energy will not occur without a source of energy
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what is an example of an energy releasing reaction?
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hydrogen gas burning, or reacting, with oxygen to produce water vapor
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what is energy released in the form of?
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heat and sometimes hydrogen gas explodes, light and sound
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in order to stay alive, organisms need to carry out what?
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need to carry out reactions that require energy
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because matter and energy are conserved in chemical reactions, every organism must have what to carry out chemical reactions?
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must have a source of energy to carry out chemical reactions
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humans release the energy to grow tall, to breathe, to think, and even to dream through the chemical reactions that occur when humans what?
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metabolize, or break down, digested food
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what do chemists call the energy that is needed to get a reaction started?
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activation energy
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Some chemical reactions that make life possible are too slow or have activation energies that are too high to make them practical for what?
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living tissue
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what is a catalyst?
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a substance that speeds up the rate of a chemical reaction
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how do catalysts work?
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by lowering a reaction's activation energy
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what are enzymes?
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proteins that act as biological catalysts
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what do enzymes speed up?
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chemical reactions that take place in cells
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your bloodstream contains an enzyme called what?
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an enzyme called carbonic anhydrase that speeds up the reaction by a factor of 10 million. the reaction thakes place immediately and carbon dioxide is removed from the blood quickly
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why are enzymes very specific?
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they generally catalyzing only one chemical reaction. for this reason, part of an enzyme's name is usually derived from the reaction it catalyzes.
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carbonic anhydrase gets its name because it?
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catalyzes the reaction that removes water from carbonic acid
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how does a chemical reaction take place?
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for a chemical reaction to take place,the reactants must collide with enough energy so that existing bonds will be broken and new bonds will be formed.
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what happens when reactants do not have energy?
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unchanged after the collision
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what provides a site where reactants can be brought together to react?
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enzymes, such a site reduces the energy needed for reaction
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what are reactants of enzyme-catalyzed reactions known as?
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substrates
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enzymes help do what in your body?
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help digest food,work best at certain pH values.
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what are enzymes affected by?
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any variable that influences a chemical reactions. affected by changes in temperature.
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at what temp. does enzymes work best at?
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37 degrees Celsius, the normal temperature of the human body
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what can regulate the activities of enzymes in a variety of ways?
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cells, most cells contain proteins that help to turn key enzymes on or off at critical staes in the life of the cell.
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enzymes play essential roles in what?
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regulating chemical pathways, making materials that cells need, releasing energy, and transferring information.
