Chem Cramming! only for mocks

Question 1

define covalent bonding

Answer 1

electrostatic forces betweem a pair of shared electrons between 2 atoms

Question 2

state the intermolecular forces

Answer 2

temporary dipole and permanent dipole

Question 3

explain instantaneous dipole-induced dipole forces

Answer 3

these are weak forces that can be easily broken because elecrons are always shifting hence its temporary. Id-id forces inrease with increasing atomic number and number of electrons in a molecule and. down the group Id-id forces also increase due to increasing number of electrons

Question 4

explain permanent dipole dipole forces

Answer 4

this is hydrogen bonding; occurs when a hydrogen is bonded to an electronegative element i.e N,F,O

Question 5

define electronegativity

Answer 5

this is the tendancy of an atom to withdraw electrons to itself in a covalent bond

Question 6

describe the electronegativity trends

Answer 6

across a group electronegativity increases

down a group electronegativity decreases

Question 7

electronegativity calculations

Answer 7

you subtract the smallest electronegativity from the biggest one
>1.7 = ionic and at least one of the elements must be a metal
>0.5 but <1.7 polar covalent
<0.5 = non poar covalent

Question 8

group 13 molecular shapes

Answer 8

trigonal planar
bond angle = 120
BF3

Question 9

group 14 molecular shape

Answer 9

tetrahedral
bond angle = 109.5
CH4

Question 10

group 15 molecular shape

Answer 10

pyramidal
bond angle = 107
NH3

Question 11

group 16 molecular shape

Answer 11

angular
bond angle = 104.5
H2O

Question 12

group 15, period 3

Answer 12

trigonal bipyramidal
bond angle = 90
PF5

Question 13

group 16, period 3

Answer 13

square pyramid
bond angle = 90
SF6

Question 14

1 lone pair and no. of electron pairs

Answer 14

3ep- angular
4ep- trigonal pyramidal
6ep- square pyramid

Question 15

0 lone pairs and no. of electro pairs

Answer 15

2ep- linear
3ep- trigonal planar
4ep- tetrahedral
5ep- trigonal bypyramidal
6ep- octahedral

Question 16

state and explain characteristics of covalent bonds

Answer 16

bond polarity- due to uneven distribution of electron cloud; bond is said to have dipole moment
bond energy- energy required to break 1 mole of gaseous atoms; the greater the BE the stronger the bond
bond length- internuclear distance between a pair of atoms; longer the distance the weaker the bond and more reactive it is

Question 17

pie and sigma bonds

Answer 17

single bond- 1sigma
double bond- 1sigma 1pi
triple bond- 1sigma 2pi