bonding 2

Question 1

what is ionic bonding

Answer 1

electrostatic force of attraction between oppositely charged ions formed by electron transfer

Question 2

what are electrostatic forces of attraction in an ionic lattice

Answer 2

ions in lattice are attracted to every other oppositely charged ion

Question 3

physical properties of ionic compounds

Answer 3

1. high melting and boiling point - due to large amount of energy to overcome strong electrostatic forces of attraction
2. soluble in polar solvents - soluble substance e.g water, surrounds the ions and overcome electrostatic forces between the ions
   (if charge of ions increase, solubility decreases as water cannot overcome the electrostatic forces of attraction)

3.do NOT conduct electricity when solid - ions locked in place by electrostatic forces of attraction and cant carry a charge
dissolved in water + conducts electricity as they’re free to move

Question 4

what molecule has bond angle 180

Answer 4

linear
e.g beryllium chloride
Cl – Be – Cl

Question 5

which molecule has bond angle 104.5

Answer 5

v - shaped or non linear
e.g H2O

Question 6

which molecule has bond angle 120

Answer 6

trigonal planar
e.g BF3

Question 7

which molecule has bond angle 107

Answer 7

triangular pyramid
e.g NH3

Question 8

which molecule has bond angle 109.5

Answer 8

tetrahedral
e.g CH4 methane / NH3 ammonium

Question 9

which molecule has bond angle 90 AND 120

Answer 9

trigonal bipyramid
e.g PCl5

Question 10

which molecule has bond angle 90

Answer 10

octahedral
e.g SF6

Question 11

for every lone pair present, what happens to the bond angle between covalent bonds

Answer 11

reduced by 2.5 degrees

Question 12

how are dative bonds presented

Answer 12

indicated using an arrow from lone electron pair
H
|
H —- N ➜ H
|
H

Question 13

why do lone pairs reduce bond angle by 2.5 degrees

Answer 13

repel more strongly than bonding pairs

Question 14

define electronegativity

Answer 14

ability of an atom to attract a pair of electrons in a covalent bond

Question 15

what happens to electronegativity ALONG a PERIOD

Answer 15

increases

Question 16

what does the power of electronegativity depend on

Answer 16

1. size of positive charge on nucleus
   (more protons = increased positive charge ➜ increases attraction between nucleus and pair of electrons in covalent bond
2. atomic radius
   (smaller atomic radius = closer bonding electrons to nucleus )
   L➜R (periodic table) atomic radius decreases
3. shielding of nucleus of nucleus by electrons in inner shells
   (more inner shells + lower electronegativity)

Question 17

whats a dipole

Answer 17

a separation of charge

Question 18

whats a pure covalent bond

Answer 18

has no dipole

Question 19

what does delta δ show

Answer 19

shows that the charge is small
as the electron pair has shifted towards the MORE electronegative atom

Question 20

where does the delta negative δ- go

Answer 20

goes on more electronegative element

Question 21

name the 3 intermolecular forces

Answer 21

1. van de waals forces (induced dipole)
2. permanent dipole
3. hydrogen bonding

Question 22

whats a polar bond

Answer 22

bonding of two atoms with different electronegativites

Question 23

what are simple molecular substances

Answer 23

substances with small molecules
each molecule has fixed number of atoms

Question 24

where do intermolecular forces take place

Answer 24

in-between molecules

Question 25

intermolecular forces properties

Answer 25

weaker than covalent bonds easily broken by high temp

Question 26

what happens when intermolecular forces are heated

Answer 26

molecules move faster intermolecular forces break at a certain temp causes molecules to move away from each other

Question 27

why do intermolecular forces have low boiling point

Answer 27

small amount of energy to break intermolecular forces

Question 28

what are induced dipole-dipole interactions (van de waals)

Answer 28

- weakest type of intermolecular force - caused by random electron movement - acts as an induced dipole between molecules

Question 29

what does strength of van de waals depend on

Answer 29

depends on number of electrons (larger amount of electrons = higher boiling point - experience stronger van de waals)

Question 30

what are permanent dipole-dipole interactions

Answer 30

when permanent dipoles leads to attraction acts between polar molecules δ+ and δ- attract each other hold molecules together in lattice-like structure

Question 31

what is the strongest type of intermolecular force

Answer 31

hydrogen bonding

Question 32

what is the weakest type of intermolecular force

Answer 32

van de waals

Question 33

where do hydrogen bonds only form between

Answer 33

between 3 most electronegative atoms: nitrogen oxygen fluorine | (all have at least one lone pair of electrons)

Question 34

what two conditions are needed for hydrogen bonding to take place

Answer 34

1. hydrogen atom bonded to strong electronegative element 2. electronegative atom must have at least one lone pair of electrons

Question 35

what is hydrogen bonding

Answer 35

type of permanent dipole dipole bond strongest intermolecular forces between neutral molecules act between molecules containing permanent dipoles

Question 36

why does water have a high melting and boiling point

Answer 36

it takes a great deal of energy to break the hydrogen bonds

Question 37

properties of after due to hydrogen bonding

Answer 37

ice is less dense of liquid form therefore ice floats on water liquid water = water molecules moving randomly freezing point = water molecules in ordered structure = ice - stabilised by hydrogen bonds (in ice - water molecules are further apart than in liquid water making it less dense & floats)

Question 38

what bond is between atoms of simple molecular substances

Answer 38

covalent

Question 39

what do simple molecular substances have

Answer 39

small molecules with fixed number of atoms

Question 40

2 examples of giant covalent structures

Answer 40

diamond and graphite

Question 41

properties of simple molecular substances

Answer 41

low melting and boiling points due to weak intermolecular forces

Question 42

what happens when you cool a simple molecular substance below its melting point

Answer 42

becomes a solid simple molecular lattice

Question 43

molecule of iodine

Answer 43

consists of two iodine atoms joined by a single covalent bond with intermolecular forces between the molecules

Question 44

what are non-polar molecules

Answer 44

atoms that have same electronegativity means that only van de waals can act between the molecules

Question 45

what the solubility of simple molecular substance depend on

Answer 45

depends on whether the substance is polar or none polar

Question 46

iodine solubility

Answer 46

solid at room temp iodine molecules held in simple molecular lattice by van de waals

Question 47

what happens when non polar substances e.g iodine dissolve in non polar substances

Answer 47

solvent molecules form van de waals to iodine molecules

Question 48

why are non polar substances insoluble in polar e.g water solvents

Answer 48

molecules with hydrogen bond remain hydrogen bonded rather than forming van de waals with non polar molecules

Question 49

general rule of polar substances

Answer 49

polar substances dissolve in polar solvents

Question 50

where does hydrogen bonding take place

Answer 50

in compounds that have a hydrogen atom attached to one of the three most electronegative atoms