Glossary of AP Biology Chapter 2
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- List the levels of organization
- Atom, molecule, organelle, cell, tissue, organ, organ system, organism, population, community, ecosystem, biosphere
- Atom
- Smallest unit of matter that still retains the properties of an element
- Element
- Substance that cannot be broken down
- Molecule
- A group of two or more atoms with covalent bonds
- Compound
- Ex: proteins. Substance containing two or more elements in a fixed ratio.
- Four chemicals most abundant in living matter
- Oxygen, carbon, hydrogen, nitrogen
- Other chemicals needed by the body
- Calcium and phosphorus, idodine (in trace amounts), fluoride.
- proton
- Subatomic particle with a single positive electrical charge
- Electron
- Subatomic particle with a single negative charge
- Neutron
- electrically neutral subatomic particle
- Nucleus
- Atom's central core, contains protons and neutrons
- Atomic number
- Number of protons in element
- Mass number
- Protons plus neutrons
- Isotopes
- Same element, different mass number. Example: carbon-13 and Carbon-12
- radioactive isotope
- Nucleus decays spontaneously.
- Importance of radioactive isotopes
- Tracers for monitoring the fate of atoms in living organisms; studying photosysthesis; diagnose kidney disporders; indicate cancer.
- Electron shell information
- 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
- What is an ionic bond? Give an example.
- Two opposite charges (stealing electrons). NaCl. Sodium chloride is called a salt because it exists as a crystal
- What is a covalent bond? Give an example
- Two nonmetals bonding. Atoms share one or more pairs of outer shell electrons. O2.
- What is the difference between double, single, and triple covalent bonds?
- The number of shared pairs of electrons.
- Electronegativity
- An atom's attraction for its electrons. The more electronegative an atom, the more strongly is pulls shared electrons to its nucleus.
- Difference in polar and nonpolar covalent bonds
- Nonpolar covalent bonds share electrons equally. Polar do not. Water is polar.
- Why is ice less dense than water?
- 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.
- Why is water a great solvent?
- Because of the polarity of its molecules
- Definition of Acid
- Donates hydrogen ions to solution
- Definition of Base
- Accepts hydrogen ions and removes from solution
- What does each number represent on the pH scale as you go up?
- Each unit represents a tenfold change in the concentration of hydrogen ions in solution.
- What are buffers?
- buffers resist changes in pH by accepting Hydrogen when it is in excess and donating it when it is depleted.
- Why does acid precipitation occur?
- 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.
- What is a chemical reaction?
- A process leading to changes in the composition of matter. Reactants yield products.