SHAPES OF MOLECULE

Question 1

CH4 SHAPE AND BOND ANGLE

Answer 1

Tetrahedral

109.5

Question 2

NH3 SHAPE AND BOND ANGLE

Answer 2

pyramidal

107

Question 3

H20 SHAPE AND BOND ANGLE

Answer 3

Bent

104.5

Question 4

BF3 SHAPE AND BOND ANGLE

Answer 4

trigonal planar

120

Question 5

ELECTRONEGATIVITY DIFFERENCE OF A COVALENT BOND

Answer 5

0

Question 6

ELECTRONEGATIVITY DIFFERENCE OF A POLAR COVALENT BOND

Answer 6

0 - 1.8

Question 7

ELECTRONEGATIVITY DIFFERENCE OF AN IONIC BOND

Answer 7

more than 1.8

Question 8

WHAT MAKES A BOND POLAR

Answer 8

when the bonded atoms have a different electronegativity value therefore the bonded electron pair is shared unequally

Question 9

WHAT IS A DIPOLE

Answer 9

the separation of opposite charges

Question 10

WHAT ARE INTERMOLECULAR FORCES and what is the order of strength

AND THE THREE CATEGORIES

Answer 10

weak interactions between dipoles of different molecules

London forces
Permanent dipole dipole interactions
Hydrogen bonding

Question 11

What is electronegativity

Answer 11

the ability for an atom to attract electrons towards itself in a covalent bond

Question 12

2 examples of polar covalent bonds

Answer 12

H-Cl H-O-H

Question 13

Why is CO2 not polar

Answer 13

as it has 2 polar bonds that are arranged symmetrically so no overall polarity

Question 14

What is an induced dipole-dipole

Answer 14

a temporary dipole created when atoms or molecules are near each other so electrons can move from one end to another

Question 15

How are crystal structures held together

Answer 15

Induced dipole-dipole forces hold molecules together,(covalent bonds hold the atoms together)

Question 16

What happens when you boil a liquid

Answer 16

You break the weak induced dipole-dipole forces, NOT THE COVALENT BONDS

Question 17

difference of boiling points of straight chain hydrocarbons and branched hydrocarbons

Answer 17

Straight chain hydrocarbons can pack together tighter, therefore there are more stronger induced dipole-dipole forces so the boiling point is high

Branched hydrocarbons cant pack together as close therefore the induced dipole-dipole forces are weaker and boiling point is therefore lower

Question 18

What is a dipole-dipole force

Answer 18

weak electrostatic force that exists between molecules with polarity

Question 19

What is a test for polar molecules

Answer 19

run a steady stream of the liquid near a charged rod, the liquid will bend towards the rod if polar as the molecules align to face the rod

Question 20

When does hydrogen bonding occur

Answer 20

when hydrogen on one molecule forms a bond with the lone pair on either nitrogen, oxygen or fluorine as they are very electronegative

Question 21

Trend in boiling points of hydrogen halides

Answer 21

HF, HI, HBr, HCl

HF has hydrogen bonding so will need the most energy to overcome the electrostatic forces, the other 3 do not, so as the mass of the molecule increases, so does the size of the electron cloud, and so more induced dipole-dipole forces