11. Measurement

Above or below true value, usually due to equipment (repetition of at least 3, range of 5)

In one direction, usually due to instrument / method error eg physical errors in the measuring device, improper or sloppy use of measuring device, ambient conditions

A measure of the certainty

How close the value is to the accepted value

Ionization –> Acceleration –> Deflection –> Detection

• vacuum • callibrated with 12C • all living things composed w/ 12C • solid in room tempt –> easy to store and transport • abundant • Lighter ions/ positive charges deflect more • Mass/Charge ratio m/z

• Molecules that absorb infrared radiation have fluctuating dipole moments • When molecules absorb infrared radiation they can bend, stretch and/ or vibrate (symmetrically / asymmetrically) • I.R. Active mode of vibration

• Looks at protons in hydrogen atoms • proton spins act as magnets –> uses energy to line up with or against magnetic field –> energy measured in the radiowave region • chemical environments

• Degree of unsaturation in organic compounds • double bond/ ring = 1 degree • triple bond = 2 degree • aromatic ring = 4 degree • IHD = 0.5(2C + 2 - h - x - n)

• Spin-spin coupling creates slightly different energy levels creating split in peaks • n + 1 rule • CH2 next to CH3 splits the CH3 peak into 3 • CH3 next to CH2 splits the CH2 peak into 4 peaks • CH next to CH3 splits the CH3 into 2 peaks • The proton on a hydroxyl group generally does not split • shields adjacent H protons as well

• Hydrogens are all in the same environment so only one reference line is produced given a value of σ=0ppm • Si has a lower electronegativity than C so Si-H lines do not overlap with C-H ones • Chemically intert, soluble organic solvents, can be easily removed by boiling

• constructive interferance - when waves are in phase, they can be added together • used to determine bond length, bond angles and crystalline structure

• TV remote • Heat sensor • Global warming • H2O and CO2 bonds that absorb IR radiation because of tehir fluctuating dipoles • UV high energy, shorter wavelength ; IR lower energy, longer wavelength

• Breathalyser • MRI scans • Magnetic resonance imaging –> non invasive • detects protons in 1H atoms of water molecules