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22 Cards in this Set
- Front
- Back
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When is an atom in ground state?
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When it's electrons are in the lowest energy levels.
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When is an atom in an excited state?
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When it's electrons absorb energy and move to a higher energy level
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What are isotopes?
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Atoms of one element that vary only in the number of electrons.
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What is the difference between carbon-12 and carbon-14
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Carbon-12 has 6 protons and 6 neutrons, where carbon-14 has 6 protons and 8 neutrons.
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What are radioisotopes? Give an example.
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radioactive isotopes. carbon-14
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Give an example of a tracer. What could it be used for?
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A radioactive carbon which can be incorporated into a molecule to trace the path of CO2 in a metabolic pathway.
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When is a bond formed?
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When two atomic nuclei attract the same electrons.
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How is energy involved in bonding?
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Energy is released forming the bond and required to break the bond.
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Why do atoms bond?
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Atoms bond to get a stable configuration, by having a complete outer shell.
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How do ionic bonds form? What do they result in?
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Form from the transfer of electrons. They form a positive ion (gives up the electron) and a negative ion (gains the electron).
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When do covalent bonds form? What do they result in?
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Form from the sharing of electrons. Resulting structure is a molecule.
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What are the two types of covalent bonds?
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polar and non-polar
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What are non-polar bonds and where are they found?
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When electrons are shared equally between two atoms. They are found in diatomic molecules ex H2, or O2.
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What are polar bonds and where are they found?
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Electrons are shared unequally. They exist between any two or more atoms that are not the same, ex: CO2.
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Anytime two or more atoms form a bond, the entire bond is either ______ or ________.
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polar or non-polar
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What is a non-polar molecule? Give an example.
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A molecule that is symmetrical, ex: CO2.
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What is a polar molecule? Give an example.
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An asymmetrical molecule. Ex: H2O.
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What are the attractions like between polar and nonpolar molecules? What does this determine about their substances?
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Bonds are strong between polar molecules and weak between non-polar molecules. It determines their physical characteristics such as solubility.
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What can be stated about substances dissolving in another?
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"like dissolves like". non-polar substances dissolve in non-polar solutions and polar substances dissolve in polar solutions.
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Explain why gas escapes from a pop can, commenting on the intermolecular bonds of atoms.
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Because CO2 is a linear molecule, it is nonpolar and when put in water, a polar substance, it will not dissolve because "like dissolves like". Therefore, when the pop can is opened, the gas is able to escape from the water.
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Explain why, commenting on the intermolecular bonds how transport occurs through the plasma membrane of a cell.
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Because the plasma membrane is a phospholipid bilayer, and lipids are non-polar molecules, only non-polar molecules are able to dissolve through it. Large polar molecules have to be transported across a hydrophilic membrane in special (protein) channels.
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What does hydrophobic and hydrophilic mean?
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Hydrophobic - "repelled by water"
Hydrophilic -"attracted to water" |
