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30 Cards in this Set
- Front
- Back
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List the levels of organization
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Atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere
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Atom
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Smallest unit of matter that still retains the properties of an element
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Element
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Substance that cannot be broken down
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Molecule
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A group of two or more atoms with covalent bonds
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Compound
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Ex: proteins. Substance containing two or more elements in a fixed ratio.
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Four chemicals most abundant in living matter
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Oxygen, carbon, hydrogen, nitrogen
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Other chemicals needed by the body
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Calcium and phosphorus, idodine (in trace amounts), fluoride.
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proton
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Subatomic particle with a single positive electrical charge
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Electron
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Subatomic particle with a single negative charge
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Neutron
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electrically neutral subatomic particle
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Nucleus
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Atom's central core, contains protons and neutrons
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Atomic number
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Number of protons in element
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Mass number
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Protons plus neutrons
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Isotopes
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Same element, different mass number. Example: carbon-13 and Carbon-12
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radioactive isotope
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Nucleus decays spontaneously.
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Importance of radioactive isotopes
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Tracers for monitoring the fate of atoms in living organisms; studying photosysthesis; diagnose kidney disporders; indicate cancer.
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Electron shell information
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The farther an electron is from the nucleus, the greater its energy. Atoms whose outer shell is not full tend to participate in chemical reactions
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What is an ionic bond? Give an example.
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Two opposite charges (stealing electrons). NaCl. Sodium chloride is called a salt because it exists as a crystal
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What is a covalent bond? Give an example
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Two nonmetals bonding. Atoms share one or more pairs of outer shell electrons. O2.
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What is the difference between double, single, and triple covalent bonds?
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The number of shared pairs of electrons.
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Electronegativity
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An atom's attraction for its electrons. The more electronegative an atom, the more strongly is pulls shared electrons to its nucleus.
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Difference in polar and nonpolar covalent bonds
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Nonpolar covalent bonds share electrons equally. Polar do not. Water is polar.
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Why is ice less dense than water?
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because as it freezes the hydrogen bonds are stable and each water molecule forms H bonds with 4 neighbors at 'arm's length' creating a crystal. In liquid H2O, hydrogen bonds are constantly broken and re-formed.
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Why is water a great solvent?
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Because of the polarity of its molecules
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Definition of Acid
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Donates hydrogen ions to solution
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Definition of Base
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Accepts hydrogen ions and removes from solution
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What does each number represent on the pH scale as you go up?
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Each unit represents a tenfold change in the concentration of hydrogen ions in solution.
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What are buffers?
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buffers resist changes in pH by accepting Hydrogen when it is in excess and donating it when it is depleted.
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Why does acid precipitation occur?
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Results mainly from the presence of sulfur oxides and nitrogen oxides. The oxides react with water vapor in air to form sulfuric acid and nitric acid.
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What is a chemical reaction?
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A process leading to changes in the composition of matter. Reactants yield products.
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