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Qualitative Analysis
Analysis based on measurements and associated uncertainties.
Quantitative Analysis
Comes from measurements and is always associated with uncertainties determined by either the apparatus or human limitations such as reaction times and sight.
Precision
Closeness of agreement between test results.
Accuracy
Closeness of agreement between a measurement result and the true value.
Scientific Notation
A way to express extremely large/small numbers in a compact form as a coefficient multiplied to a power of 10 (a x 10^n).
Significant Figures
Digits reflecting the precision of a measurement.
Experimental Error
Uncertainty associated with a measurement due to systematic or random errors.
Systematic Error
A flaw in experimental design or methodology. This affects the accuracy of the results.
Random Error
Occurs because of uncontrolled variables. Cannot be eliminated. This affects the precision of the results.
Absolute Uncertainty
Margin of uncertainty associated with a measurement result.
Relative Uncertainty
Ratio comparing the size of absolute uncertainty to the measurement.
Graphical Techniques
Methods to show the relationship between variables in graphs.
Sketched Graph
Graphs with labeled but unscaled axes, used to show qualitative trends such as proportional or inversely proportional relationships. Units are not required.
Drawn Graph
Graphs with labeled and scaled axes, based on quantitative measurements. They always display appropriate units for variables.
Dependence
Any statistical relationship between two sets of data or random variables.
Independent Variable
The variable that represents the cause, plotted on the x-axis in a graph of Y versus X.
Dependent Variable
The variable that represents the effect, plotted on the y-axis in a graph of Y versus X.
Correlation
Statistical measure indicating the relationship between variables.
Positive Correlation
A relationship where two variables increase or decrease in parallel.
Negative Correlation
A relationship where one variable increases while the other decreases, or vice versa.
Correlation Coefficient ( r )
A measure of the strength of the relationship between two variables, represented by the symbol r.
Scatter Plot
A graph that shows the scatter of various points, representing the relationship between two variables.
Degree of Unsaturation
Index used to determine the number of rings or double bonds in a compound.
Electromagnetic Spectrum
Range of electromagnetic radiation used in spectroscopy techniques.
r = +1
Indicates a perfect positive linear relationship where all points lie on a straight line.
r=0
Indicates no linear relationship; the points are completely scattered.
r=−1
Indicates a perfect negative linear relationship where all points lie on a straight line.
Slope (m)
The tangent of the angle (θ) that the line makes with the positive direction of the x-axis.
Intercept (c)
The point where the line cuts the y-axis at x=0.
Extrapolation
The process of estimating values beyond the given data range based on the trend of the data.
Equation of a Line
Represented as y=mx+b, where m is the slope and b is the y-intercept.
Best Fit Line
A straight line that minimizes the distance between itself and the data points in a scatter plot.
Degree of Unsaturation (IHD)
A measure used to determine the number of rings or double bonds in a molecular formula.
Double Bond
Contributes 1 IHD.
Triple Bond
Contributes 2 IHD.
Ring
Contributes 1 IHD.
Aromatic Compound
Contributes 4 IHD (3 double bonds + 1 ring).
IHD Formula
For CcHhNnOoXx: IHD=0.5(2c+2−h−x+n).
Electromagnetic Spectrum (EMS)
The range of all types of electromagnetic radiation. Different regions of the spectrum form the basis for various types of spectroscopy.
Planck's Equation
Relates the energy of radiation (E) to its frequency (v): E=hv, where h=6.63×10−34 J⋅s.
X-ray Spectroscopy
Uses high-energy X-rays to remove electrons from inner atomic energy levels, providing structural information such as bond distances and angles (basis of X-ray crystallography).
UV-Vis Spectroscopy
Based on visible and UV light causing electronic transitions, providing information about the electronic energy levels in atoms or molecules.
Infrared (IR) Spectroscopy
Uses IR radiation to cause molecular vibrations (stretching, bending, twisting) that provide information about functional groups.
Microwave Spectroscopy
Causes molecular rotations and provides information about bond lengths.
NMR Spectroscopy
Uses radiowaves in a strong magnetic field to induce nuclear spin transitions, giving information about the chemical environments and connectivity of atoms in a molecule.
Infrared Spectroscopy (Spring Model)
Covalent bonds are modeled as springs that stretch, bend, or twist, causing molecular vibrations. This model forms the basis for IR spectroscopy.
Hooke's Law
Describes the force required to cause vibration in the spring model of IR spectroscopy.
Vibration Frequency
Lighter atoms vibrate at higher frequencies; heavier atoms vibrate at lower frequencies.
Multiple Bonds
Multiple bonds (e.g., double and triple bonds) follow the same trend as lighter atoms, vibrating at higher frequencies.
Bond Enthalpy and Absorption
Different molecules absorb at different frequencies due to variations in bond enthalpy.
Wavenumber
IR absorptions are typically reported as wavenumber (1/λ), measured in cm−1.
Proton NMR Spectroscopy (¹H NMR)
Provides information about the different chemical environments of hydrogen atoms in a molecule.
Spin States of Hydrogen Nuclei
Based on the principle that hydrogen nuclei have two possible spin states and act like tiny magnets.
Chemical Shift
The position of the spin relative to the standard spin (tetramethylsilane, TMS).
Hydrogen Ratio
Provides the relative number of hydrogens in each environment, presented as a ratio.
Area Under the Curve
The area under the curve in an NMR spectrum corresponds to the number of hydrogens in that environment.
Mass Spectroscopy
Provides additional information about functional groups in a molecule.
Molecular Ion (M⁺)
Formed when a gaseous molecule is ionized; represents the intact molecule's ion.
Fragmentation Pattern
The pattern in a mass spectrum showing the masses of fragments after functional groups are removed.
Molecular Ion Peak
The peak in a mass spectrum corresponding to the molecular mass of the compound.
Note 
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