L IQUIDS Molecules at an intermediate state between the ordered state of the solid and the disordered state of the gas

T HE L IQUID S TATE A liquid flows by sliding molecules over one another Viscosity – measure of a liquid’s resistance to flow Increases with intermolecular forces Increases with molecular size Usually decreases with an increase in T Structural Model for Liquids Strong intermolecular forces (like solids) Considerable molecular motion (like gases)

T HE L IQUID S TATE Surface tension – the resistance of a liquid to an increase in its surface area High intermolecular forces = greater surface tension Bulk molecules (those in the liquid) are equally attracted to their neighbors Surface molecules are only attracted inward towards the bulk molecules Surface molecules are packed more closely than bulk molecules Causes the liquid to behave as if it had a “skin”

S URFACE T ENSION Water has a high surface tension – H-bonding Hg has even higher surface tension Very strong metallic bonds between Hg atoms

S URFACE T ENSION Cohesive forces – intermolecular forces between liquid molecules Bind molecules together Adhesive forces – intermolecular forces that bind molecules to a surface Between polar liquid molecules and polar bonds in the material making up the container

S URFACE T ENSION Water’s adhesive forces are greater than its cohesive forces which is why it increases its surface area Concave meniscus Oxygen in glass is attracted to hydrogen in water

C APILLARY A CTION The rise of liquids up very narrow tubes The liquid climbs until adhesive and cohesive forces are balanced by gravity