bonding + shapes of molecules

Question 1

orbital

Answer 1

region around nucleus that can hold up to 2 electrons of opposite spins

Question 2

order of decreasing size, orbitals, sub shells, electrons, shells

Answer 2

shells > sub shells > orbitals > electrons

Question 3

how does metallic bonding work

Answer 3

valence electrons in metal atom delocalise + form sea of free electrons - attraction between metal cations and delocalised electrons

Question 4

why don’t metals dissolve easily

Answer 4

strong electrostatic attraction between cations and electrons

Question 5

why is diamond a good thermal conductor

Answer 5

rigid structure means that vibrations easily can carry heat through the structure

Question 6

why does graphite conduct electricity

Answer 6

one electron from each atom is delocalised, so it can move through the lattice and conduct energy

Question 7

does silicon conduct electricity

Answer 7

yes - it is a semi conductor - conducts better when hotter as electrons have more energy

Question 8

dative covalent bond

Answer 8

where both electrons from the shared pair are supplied by one atom only

Question 9

average bond enthalpy

Answer 9

measure of the strength of a bond - larger value = stronger bond

Question 10

London (dispersion forces) permanent?

Answer 10

no

Question 11

London (dispersion forces) strength

Answer 11

weakest - depends on number of electrons in the molecule

Question 12

London (dispersion/ Van Der Waal’s) forces

Answer 12

electrons are on one side of the molecule - instantaneous dipole - induces dipole in neighbouring molecules

Question 13

permanent dipole-dipole strength (what molecules)

Answer 13

stronger then London forces - depends on number of electrons in the molecule

Question 14

permanent dipole-dipole

Answer 14

dipole-dipole permanent interaction in POLAR molecules

Question 15

hydrogen bonding

Answer 15

not a bond - an intermolecular force

Question 16

hydrogen bonding requirements

Answer 16

must have H bonded to either F, O or N (v. electronegative)

must have lone pair of electrons

Question 17

London (dispersion/ Van Der Waal’s) forces caused by

Answer 17

electron movement, giving an uneven electron distribution, inducing temporary dipole-dipole interaction in neighbouring molecules

Question 18

hydrogen bonding strength

Answer 18

strongest

Question 19

electronegativity trend down a group

Answer 19

decrease - shielding increase, atomic radius increase, less attraction

Question 20

electronegativity

Answer 20

the power of an atom to attract the two electrons in a covalent bond

Question 21

electronegativity across a period

Answer 21

increase - shorter atomic radius, same shielding, greater nuclear charge, stronger force of attraction between bonding pair and nucleus

Question 22

why do ionic compounds dissolve in water

Answer 22

ions for polar bonds with water molecules

Question 23

principle quantum number

Answer 23

shell number or energy level (n)

Question 24

solubility of ionic substances

Answer 24

generally soluble in polar solvents

Question 25

2 processes which must occur for an ionic substance to be soluble

Answer 25

- lattice must be broken down | - solvent molecules must attract and surround ions

Question 26

trend in ionic solubility as ionic charge increases

Answer 26

decrease

Question 27

solubility depends on...

Answer 27

relative strengths of attractions within giant ionic lattice and attractions between ions and solvent molecules

Question 28

electrical conductivity of ionic substances

Answer 28

solid = unconductive | liquid/in solution = conductive

Question 29

covalent bonding

Answer 29

strong electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms

Question 30

covalent molecule

Answer 30

smallest part of a covalent compound that can exist whilst retaining the chemical properties of the compound

Question 31

why do more bonds often = more stable

Answer 31

as energy released when bonds made, so becomes more stable

Question 32

factors affecting electronegativity

Answer 32

- nuclear charge - atomic radius - shielding

Question 33

element with highest electronegativity

Answer 33

fluorine

Question 34

intermolecular forces in molecule with no polar bonds

Answer 34

van der Waals

Question 35

intermolecular forces in molecule containing some polar bonds but all dipole moments cancel out (ie. linear)

Answer 35

van der Waals

Question 36

intermolecular forces in molecule containing polar bonds and all dipole moments DO NOT cancel out

Answer 36

van der Waals AND dipole-dipole or H-bonding depending on molecule

Question 37

non-polar covalent bond

Answer 37

2 atoms in a covalent have same electronegativity (eg. Cl-Cl) - 2 electrons shared equally

Question 38

polar covalent bond

Answer 38

2 atoms in covalent bond have different electronegativities - 2 electrons not shared equally (eg. H-Cl)

Question 39

solubility of non polar substances in polar solvents

Answer 39

insoluble/slightly soluble

Question 40

solubility of non polar substances in non-polar solvents

Answer 40

usually soluble - intermolecular forces form between solvent and solute molecules