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U of S. Carolina - Chemistry 105 - Test 2
Notecards for Chemistry 105 Test 2 at University of South Carolina
51
Chemistry
Undergraduate 2
10/12/2011

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Term
Name of Element that is Named After Mary Cluric
Definition
Polonium
Term
Henri Becquerel (1896)
Definition
Experimented with phosphorescence of certain materials (uranium)
Term
Earnest Rutherford (1899)
Definition
Found that alpha rays could be stopped by thin pieces of paper. Whereas beta rays were only stopped by at least 0.5 cm of lead
Term
Paul Villard (1900)
Definition
Discovered the high energy, extremely penetrating gamma ray having characteristics of light waves. Very damaging to human tissue
Term
Madame (Marie) Curie
(1859-1906)
Definition
Won the noble prize along with Henri Bacquerel for their work on radioactivity

She discovered that some elements are more radioactive than others
Term
Radioactivity
Definition
The result of a natural change of an isotope of one element into an isotope of a different element resulting in a nuclear reaction
Term
Nucleons
Definition
Protons and Neutrons

During a nuclear reaction the number of nucleons is conserved but the identity of the element changes by emitting a particle or a ray
Term
Alpha Emitters
Definition
Radioactive decay of an atom resulting in the release of an Alpha particle ad changing the identity of the atom
Term
Alpha Particle
Definition
Helium Nuclei (He)

Decreases an element's electrons by 2
Decreases an element's atomic mass by 4
Term
Beta Emitters
Definition
Radioactive decay of an atom resulting in the release of a Beta particle and changing the identity of the atom
Term
Beta Particle
Definition
An electron

Adds 1 electron to an element
Term
Gamma Rays
Definition
Highly energetic protons that is released by the excess energy remaining after a nucleus emits an alpha or beta particle
Term
Positron Emission
Definition
A proton is converted to a neutron

An element loses 1 electron
Term
Stability of Atomic Nuclei
Definition
Based on relative number of protons and neutrons
*Mass number as least twice as large as the atomic number (with the exception of Hydrogen isotopes)
**When a greater neutron/proton ratio exists (beta decay occurs)
**When a greater proton/neutron ratio exists (positron emission occurs)
**For elements greater than atomic number 83 (alpha emission occurs decreasing the number of protons and neutrons by 2)
Term
Half Life
Definition
The time required for exactly 50% of the original material to decay
Term
Radio Carbon Dating
Definition
Determining the age of a sample using the carbon-14 isotope
Term
Gamma Rays (Applications of Radioactivity)
Definition
From cobalt-60 and cesium-137 are used to irradiate food
Term
Food Radiation
Definition
Retards the growth of organisms such as molds, bacteria, and yeasts
Term
Two Ways Radioactive Isotopes Are Used
Definition
Diagnosis and Therapy
Term
Diagnosis
Definition
Radioisotopes are inserted into the patients body allowing an image to be produced of the problem area
Term
Fission
Definition
Large amounts of energy are released when heavy atomic nuclei split
Term
Fusion
Definition
Large amounts of energy are released when small atomic nuclei are combined
*Releases as much energy as fission with fewer radioactive by-products
Term
Octet Rule
Definition
In forming bonds, main-group elements gain, lose, or share electrons to achieve a stable electron configuration with eight valence electrons
Term
Ionic Bond
Definition
The attraction between positive and negative ions
Term
Ionic Compounds
Definition
Compounds composed of positive and negative ions
Term
Formula Unit
Definition
In ionic compounds, the simplest ratio of oppositely charged ions that gives an electrically neutral unit
Term
Lewis Dot Symbols
Definition
The valence electrons, represented by dots, are placed around the symbol until they are used up or until all 4 sides are occupied

**Can be used along with the octet rule to predict formulas for ionic compounds
Term
Binary Compound
Definition
Chemical compound composed of one metal and one non-metal
**Cation = metal = common name
**Anion = non-metal = name ends in -ide

Example: NaCl Sodium Chloride
Term
Polyatomic Ion
Definition
A group of atoms with a net charge that behaves as a single particle
Term
Covalent Bond
Definition
A bond in which 2 atoms share electrons to achieve a noble gas configuration
Term
Lewis Structure
Definition
Electron dot representation of valence electrons in a molecule
Term
Bonding Pair
Definition
Pair of electrons shared between 2 atoms in a molecule
Term
Nonbonding Pair
Definition
Unshared pair of valence electrons in a molecule
Term
Hydrocarbons
Definition
Compounds containing only carbon and hydrogen
Term
Alkanes
Definition
Hydrocarbons with carbon-carbon single bonds
Term
Saturated Hydrocarbons
Definition
Hydrocarbons that are alkanes
Term
Double Bond
Definition
A bond in which 2 pairs of electrons are shared between atoms
Term
Triple Bond
Definition
A bond in which three pairs of electrons are shared between atoms
Term
Electronegativity
Definition
The ability of an atom to attract electrons toward itself
**Increases from left to right on the periodic table and from top to bottom
Term
Non-Polar Bonding
Definition
Describes a bond or molecule in which charge is evenly distributed, with no positive or negative regions
Term
Polar Bonding
Definition
Describes a bond or molecule in which charge is unevenly distributed, creating positive and negative regions. Based on differences in electronegativity
Term
Shapes of Molecules
Definition
Determined from the number of bonding pairs and the number of Ion pairs on the central atom
Term
Electrolyte
Definition
A compound that conducts electricity when melted or dissolved in water
Term
Non-Electrolyte
Definition
A compound that does not conduct electricity when melted or dissolved in water, or does not separate into ions in water
Term
Intermolecular Forces
Definition
Attractive forces that act between molecules; weaker than covalent bonds
Term
Dipole-Dipole Forces
Definition
Attractive forces between polar molecules
Term
London Dispersion Force
Definition
*Very weak small molecules
*Very strong large molecules
*All molecules contain it
Term
Hydrogen Bonding
Definition
Attraction between a hydrogen atom bonded to a highly electronegative atom (O,N,F) and an electronegative atom in another or the same molecule
Term
Solids
Definition
Fixed shape and fixed volume, non-compressible, very strong intermolecular forces
Term
Liquids
Definition
Variable shape but fixed volume, strong intermolecular forces, non-compressible
Term
Gases
Definition
Variable shapes and volume, compressible, weak intermolecular forces
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