Please enable JavaScript.
Coggle requires JavaScript to display documents.
Week 1: Overview of Food Chemistry - Coggle Diagram
Week 1: Overview of Food Chemistry
Atomic Chemistry
Atoms, Ions and Molecules
Molecule: smallest particle of a substance that retains the chemical and physical properties of the substance and is composed of two or more atoms.
Most substances exist in molecular form, eg. CH4. Some metals exist in atomic form, eg., Fe, Zn.
Ion: formed when an atom loses or gains electron(s).
A positive ion (cation) is formed when an atom loses electron(s).
Cation ( + ion ) : Np+ > Ne-
A negative ion (anion) is formed when an atom gains electron(s).
Anion ( - ion ): Np+ < Ne-
Mole Concept
L = 6.023 x 10^23 mol-1
Mole : amount of substance that contains the Avogadro constant of its building units (may be atoms, molecules, ions, electrons)
Molarity And Dilution
Molarity (a concentration): No. of moles of a substance dissolved in one litre of solution
, a set unit
Concentration can have a wide range of units
mol/L
g/L
g/mL
No. of mols of substance remains the same, but volume of solution is changed by adding more solvent
Dilution = Molarity / Concentration ↓
Intermolecular Forces
Two types of intermolecular bonding:
Van der Waals forces
Permanent dipole-dipole interaction
Occurs when molecules have fixed dipole moments, eg. HCl
Tertiary structure of proteins – Van der Waals forces and hydrogen bonding
Hydrogen bonding: Interaction between a hydrogen atom bonded to O, N, or F and O, N or F on another molecule
DNA double helix – hydrogen bonding of base pairs
Effects of IMF
In solid state:
Molecules are tightly packed – held together by intermolecular forces, for eg, Van der Waals forces
In liquid state:
Molecules are further apart compared to solid state – energy is required to pull molecules apart
In gaseous state:
Molecules are further apart compared to the liquid state – more energy is required to pull molecules apart
Affects the physical and chemical properties of food:
Cooking/heat denatures proteins in egg whites – disruption of hydrogen bonds
Drying of food takes a long time due to hydrogen bonding (in water)
