Electronegativity

Question 1

electronegativity

Answer 1

the relative attraction an atom in a molecule has for the shared pair of electrons in a covalent bond

Question 2

polar covalent bond

Answer 2

one atom involved in the covalent bond has a partial negative and the other has a partially positive charge. this only happens when the electronegativity difference is big enough

Question 3

why do noble gases have no electronegativity value?

Answer 3

they do not form compounds due to already having a stable outer octet

Question 4

how do you tell which element has the positive and which has the negative dipole?

Answer 4

the element with the higher electronegativity value is always negatively charged

Question 5

how do you calculate electronegativity difference

Answer 5

find each element on the electronegativity periodic table.
subtract the smaller value from the bigger one
= en difference

Question 6

electronegativity difference for ionic bonding

Answer 6

greater than 1.7

Question 7

electronegativity difference for polar covalent bonding

Answer 7

greater than 0.4, less than or equal to 1.7

Question 8

electronegativity difference for non-polar covalent bonding

Answer 8

less than or equal to 0.4

Question 9

how do you determine the type of bond it is?

Answer 9

by looking at the electronegativity difference

Question 10

what shapes have polar bonds but are non-polar molecules

Answer 10

linear, tetrahedral, trigonal planar

Question 11

what sentence do you use when explaining symmetry?

Answer 11

centres of positive and negative charges coincide

Question 12

intramolecular bonding

Answer 12

the bonding within a molecule that holds it together
ie ionic, covalent

Question 13

intermolecular forces

Answer 13

the force of attractions between 2 SEPERATE molecules
ie van der waals, dipole-dipole, hydrogen bonding

Question 14

van der waals

Answer 14

weak forces of attraction between molecules resulting in the formation of temporary dipoles

Question 15

which molecules experience van der waals

Answer 15

ALL

Question 16

how do you explain boiling point?

Answer 16

do out as a table:
name the intramolecular bonding for each
name the intermolecular force for each
state it’s strength
how much energy is needed to overcome each of the forces (compare)

Question 17

dipole dipole

Answer 17

forces of attraction between the negative dipole on one polar molecule and the positive dipole of another polar molecule

Question 18

what molecules does dipole dipole involve

Answer 18

ONLY polar covalent

Question 19

strength of van der waals

Answer 19

weakest

Question 20

strength of dipole-dipole

Answer 20

Middle but still strong

Question 21

strength of hydrogen bonding

Answer 21

strongest

Question 22

hydrogen bonding

Answer 22

particular dipole dipole attraction between molecules where there is a hydrogen atom attached to either oxygen, nitrogen or fluorine

NOT A BOND IS BETWEEN 2 SEPERATE MOLECULES!!!

Question 23

how are hydrogen bonds soluble in water?

Answer 23

polar molecules dissolve in polar substances
because of a hydrogen bond formation between the 2 substances

Question 24

how do you explain whether a molecule is soluble in water

Answer 24

write out en difference
state whether it is polar or non-polar
State that water is polar
state whether it will form hydrogen bonds with water

*** if a polar molecule is nonpolar due to symmetry explain that centres of positive and neg charges coincide and that because of that it cannot form H bonds with water even though it has polar bonds

Question 25

what is a non-polar solvent

Answer 25

cyclohexane

Question 26

what happens when you put water near a negatively charged rod

Answer 26

the water is attracted/deflected towards the rod why? pos dipole attracted to neg charge

Question 27

what happens when you put water near a positively charged rod

Answer 27

water is also attracted/deflected towards the rod why? neg dipole attracted to pos charge

Question 28

what happens when you put cyclohexane near a charged rod

Answer 28

no deflection of liquid why? it doesn't have a pos or neg charge to be attracted to the rod

Question 29

what has to be present for a molecule to have symmetry

Answer 29

maximum 2 different elements bonded to eachother in either a: tetrahedral, trigonal planar or linear shape

Question 30

what does hydrophilic mean

Answer 30

water loving, polar soluable section

Question 31

what does hydrophobic mean

Answer 31

non polar water hating

Question 32

give an example where it has both hydrophilic and hydrophobic parts

Answer 32

the phospholipid bilayer- makes up cell membrane in cells hydrophobic tails face inward away from water hydrophilic part faces outwards towards the water

Question 33

give a real life use of hydrogen bonding

Answer 33

in DNA the base pairs are held together by H bonds forming the double helix