Atomic Structure: Bonding & Properties of Liquids

Viscosity

• The resistance of a liquid to flow (how thick is a liquid)

• A liquid flows by sliding molecules over each other.

• The stronger the IMF’s and bigger the size the higher the viscosity

Surface Tension

Cohesive Forces: Bind liquid molecules together (Cohesion)

Adhesive Forces: Bind liquid molecules to a surface (adhesion)

Meniscus Curve

The meniscus curve is the U-shape of water in a test tube.

Occurs when adhesion is strong (water is attracted to the side of the test tube or graduated cylinder)

Capillary Action

When a narrow tube is place in water, the meniscus pulls the water up the tube. Eg. xylem in plants

Boiling point of liquids

• Depends on two main factors:
  - Nature of IMFs

• Molecular Size and Shape
  

Strength of bonds

Ionic>H bonding> Dipole-Dipole>LDF

IMFs

Forces that exist between molecules:
- Vander Waals
- Dipole-Dipole
-Hydrogen Bonds

Van der Vaals

Momentary weak electrical charge. Only present in non-polar compounds.

SA determines the strength of the Van der Waals interaction. The bigger the SA, the larger the focuss and stronger IMF. Shape also affects.

Dipole-Dipole Forces

Attractive forces between permanent Dipols of polar molecules.

Hydrogen Bonding

When H is bonded to O, N, F.