Hydrogen Bonding

Question 1

Stongest IMF

Answer 1

• only happens when hydrogen is covalently bonded to fluorine, nitrogen or oxygen
• very electronegative
• draw bonding electrons away from hydrogen atom
• bond so polarized and hydrogen has such a high charge density
• its so small that hydrogen atoms form weka bonds with lone pairs of electrons
• organic molecules that f4rom hydrogen bonds often contain -OH or -NH

Question 2

Hydrogen bonds affect how substances behave

Answer 2

• high m+bp
• water 100 bp
• strength of london forces form H2S to H2Le

Question 3

group 7 hydrides

Answer 3

-molecules of HF form hydrogen bonds with each other
-so very strong and requires a lot of energy
-from HCl to HI although pdpd decrease number of electrons increase so london forces increase which overrides decrease in strength of pdpd so bp
increases

Question 4

ice floats on water

Answer 4

• simple molecular structure
• water molecules arranged so there is maximum number of hydrogen bonds
• lattice structure wastes a lot of space
• as ice melts some of hydrogen bonds broken and lattice breaks down allowing molecules to fill the space
• ice less dense than water so it floats

Question 5

alcohols

Answer 5

• contain a polar hydroxyl group that has a -delta charge on the oxygen atom and a +delta charge on hydrogen atom
• polar group helps alcohols to form hydrogen bonds
• give alcohols low volatilises compared to non-polar compounds