bonding

Question 1

ionic bonding def

Answer 1

the electrostatic force of attraction between oppositely charged ions

Question 2

when is ionic bonding stronger and the mp higher

Answer 2

when the ions are smaller and have higher charges

Question 3

why are positive ions smaller

Answer 3

it has one less shell of electrons;
ratio of protons to electrons has increased so there is a stronger attraction to hold the remaining electrons

Question 4

why are negative ions bigger

Answer 4

negative ions have more electrons than the element, but the same number of protons;
the attraction from the nucleus is shared over more electrons, making it weaker and the ions bigger

Question 5

trend in ionic radii down a group

Answer 5

size of ionic radii increases;
as you go down the ions have more shells

Question 6

covalent bond

Answer 6

the electrostatic force of attraction between the nuclei and bonding pair of electrons

Question 7

dative/coordinate covalent bond

Answer 7

when the shared pair of electrons come from only one of the bonding atoms
e.g. NH4+, H3O+

Question 8

metallic bonding

Answer 8

the electrostatic force of attraction between rhetorical positive metal ions and the delocalised electrons

Question 9

factors that affect the strength of metallic bonds

Answer 9

1. number of protons/strength of nuclear charge (more positive=stronger bond)
2. number of delocalised electrons (more delocalised electrons=stronger bond)
3. size (smaller ion=stronger bond)

Question 10

why does Mg have stronger metallic bonding than Na

Answer 10

the metallic bonding gets stronger because Mg has more electrons that become delocalised;
Mg ion is smaller and has one more proton so a higher nuclear charge;
stronger electrostatic force of attraction between the positive metal ions and the delocalised and more energy is needed to break bonds

Question 11

structure of compounds w ionic bonds

Answer 11

giant ionic lattice
e.g. sodium chloride (NaCl), magnesium oxide (MgO)

Question 12

structure of compounds w weak covalent bonds

Answer 12

simple molecular;
vdw, permanent dipoles, H bonds between molecules
e.g. iodine, CO2, H2O, CH4

Question 13

structure of compounds w strong covalent bonds

Answer 13

macromolecular;
e.g. diamond, graphite, silicon dioxide, silicon

Question 14

structure of compounds w metallic bonds

Answer 14

giant metallic lattice
e.g. magnesium, sodium, all metals

Question 15

melting and boiling points of ionic compounds/lattices

Answer 15

high;
because of giant lattice of ions with strong electrostatic forces between oppositely charged ions

Question 16

solubility in water of ionic compounds

Answer 16

generally good

Question 17

conductivity of ionic compounds when solid

Answer 17

poor; ions can’t move / fixed in place

Question 18

conductivity of ionic compounds when molten

Answer 18

good; ions can move

Question 19

melting and boiling points of simple molecular molecules

Answer 19

low; because of weak IM forces between molecules

Question 20

solubility in water of simple molecular compounds

Answer 20

generally poor

Question 21

conductivity of simple molecular molecules when solid

Answer 21

poor; no ions to conduct and electrons are fixed in place

Question 22

conductivity of simple molecular molecules when molten

Answer 22

poor; no ions

Question 23

melting and boiling points of macromolecular substances

Answer 23

high;
because of many strong covalent bonds in macromolecular structure;
takes a lot of energy to break the strong bonds

Question 24

solubility in water of macromolecular substances

Answer 24

insoluble

Question 25

conductivity of macromolecular substances when solid

Answer 25

diamond and sand: poor; because electrons can’t move (localised); graphite: good; as free delocalised electrons between layers

Question 26

conductivity of macromolecular substances when molten

Answer 26

poor

Question 27

melting and boiling points of metallic structures

Answer 27

high; strong electrostatic forces between positive ions and delocalised sea of electrons

Question 28

solubility in water of metallic structures

Answer 28

insoluble

Question 29

conductivity of molten substances when solid

Answer 29

good; delocalised electrons can move through structure

Question 30

conductivity of metallic structures of molten

Answer 30

good

Question 31

linear molecules

Answer 31

2 bonding pairs, no lone pairs, 180° e.g. CO2, CS2, HCN, BeF2

Question 32

trigonal planar

Answer 32

3 bonding pairs, no lone pairs, 120° e.g. BF3, AlCl3, SO3

Question 33

tetrahedral molecules

Answer 33

4 bonding pairs, no lone pairs, 109.5° e.g. SiCl4, SO4^2-, ClO4^-, NH4^+

Question 34

trigonal pyramidal molecules

Answer 34

3 bonding pairs, 1 lone pair, 107° e.g. NCl3, PF3, ClO3, H3O^+

Question 35

bent molecules

Answer 35

2 bonding pairs, 2 lone pairs, 104.5° e.g. OCl2, H2S, OF2, SCl2

Question 36

trigonal bipyramidal

Answer 36

5 bonding pairs, no lone pairs, 120° and 90° e.g. PCl5

Question 37

octahedral

Answer 37

6 bonding pairs, no lone pairs, 90° e.g. SF6

Question 38

electronegativity

Answer 38

the ability for an element to attract a lone pair of electrons in a covalent bond

Question 39

factors affecting electronegativity

Answer 39

electronegativity increases as: nuclear charge increases and atomic radii decreases because electrons are pulled in more so there’s a stronger attraction

Question 40

why does electronegativity decrease down the group

Answer 40

the distance between the nucleus and the outer electrons increases and the shielding of inner shell electrons increases

Question 41

formation of a permanent dipole

Answer 41

a polar covalent bond forms when the elements in the bond have different electronegativities; when a bond is polar, it has an unequal distribution of electrons and produces a charge separation

Question 42

symmetric molecule

Answer 42

all bonds identical; no lone pairs; not polar even if individual bonds within the molecule are polar e.g. CO2

Question 43

van der waals

Answer 43

occurs between all molecular substances and noble gases; not in ionic substances

Question 44

factor affecting size of vdw

Answer 44

the more electrons there are, the higher the chance that temporary dipoles will form, this makes the vdw stronger between molecules so bp will be greater

Question 45

explain the reason for increasing boiling points down group 7

Answer 45

increasing number of electrons, causing an increase in the size in vdw; iodine is solid and chlorine is a gas

Question 46

why do longer chain alkanes have stronger vdw

Answer 46

have a larger SA of contact between molecules for vdw to form than spherical shaped and branched alkanes, so stronger vdw

Question 47

permanent dipole

Answer 47

occurs between polar molecules; stronger than vdw so have higher bp; commonly compounds with C-Cl, C-F, C-Br, H-Cl, C=O; asymmetrical and have a bond where there’s a significant difference in electronegativity

Question 48

hydrogen bonding

Answer 48

when H is attached to the 3 most electronegative elements; F, O, N strongest IM force