GRE Subject Test: Biochemistry, Cell, and Molecular Biology : Help with Bonding
Study concepts, example questions & explanations for GRE Subject Test: Biochemistry, Cell, and Molecular Biology
All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
Example Questions
Example Question #1 : Biochemistry
Which three elements are capable of participating in hydrogen bonding?
Fluorine, osmium, nitrogen
Fluorine, oxygen, nitrogen
Iron (Fe), oxygen, sodium (Na)
Francium, osmium, nobelium
Francium, oxygen, nickel
Fluorine, oxygen, nitrogen
A hydrogen bond is the weak attraction of a covalently bonded hydrogen to nearby fluorine, oxygen, or nitrogen (FON) atoms. These attractions can occur within a single molecule (intramolecular) or between two distinct molecules in close proximity (intermolecular). Hydrogen bonds give water its cohesiveness and its surface tension.
Example Question #1 : Chemical Principles
The strength of bonds and intermolecular forces, from strong to weak, can be recalled by the use of the mnemonic "I Can't Handle Dirty Vans," which stands for __________.
ionic, covalent, hydrogen, dipole, van der Waals
intermediate, central, hybrid, diatomic, variable
isotonic, compound, homologous, dense, valance
indirect, chorion, high-energy, DeVries, vital
incomplete, carbon, hardy, direct, van't Hoff
ionic, covalent, hydrogen, dipole, van der Waals
Ionic bonds form when one or more electrons from an atom are removed and attached to another atom resulting in positive and negative ions that attract each other. Sodium chloride is an example of an ionic compound. Covalent bonds form when one or more pairs of electrons are shared by two atoms. Hydrochloric acid is an example of a covalent compound. A hydrogen bond is a force of attraction between a hydrogen atom in one molecule and a small atom of high electronegativity (oxygen, nitrogen, or fluorine) in another molecule. Water molecules are capable of intermolecular hydrogen bonds. A dipole-dipole bond is an attractive force between the positive end of one polar molecule and the negative end of another polar molecule. Iodine monochloride molecules show dipole-dipole attraction. Van der Waals forces arise from spontaneous changes in electron density; these occur in all chemical molecules regardless of composition and are extremely weak interactions.
Example Question #2 : Biochemistry
A mnemonic for remembering whether energy is required or released when chemical bonds are formed is __________.
BARF
SCAN
PASS
LEO says GER
RICE
BARF
Energy is absorbed when bonds break. The energy required to break the bond is absorbed from the surroundings. You have to put energy into a molecule to break its chemical bond.
Energy is released when bonds form. Bond formation represents a stable configuration of atoms. If breaking a bond absorbs energy, forming a bond must release energy; thus, the mnemonic BARF—Break (a bond), Absorb (energy), Release (energy), Form (a bond).
SCAN is the mnemonic for the magnetic field induced in a coil—south clockwise, anticlockwise north. PASS stands for pull, aim, squeeze, sweep—how to use a fire extinguisher. RICE is the treatment for an injury to a joint: rest, ice, compression, elevation. LEO says GER is a mnemonic for loss of electrons is oxidation, gain of electrons is reduction.
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All GRE Subject Test: Biochemistry, Cell, and Molecular Biology Resources
