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AL. OCR Chemistry > bonding + shapes of molecules > Flashcards

bonding + shapes of molecules Flashcards

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1
Q

orbital

A

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

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2
Q

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

A

shells > sub shells > orbitals > electrons

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3
Q

how does metallic bonding work

A

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

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4
Q

why don’t metals dissolve easily

A

strong electrostatic attraction between cations and electrons

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5
Q

why is diamond a good thermal conductor

A

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

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6
Q

why does graphite conduct electricity

A

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

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7
Q

does silicon conduct electricity

A

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

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8
Q

dative covalent bond

A

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

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9
Q

average bond enthalpy

A

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

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10
Q

London (dispersion forces) permanent?

A

no

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11
Q

London (dispersion forces) strength

A

weakest - depends on number of electrons in the molecule

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12
Q

London (dispersion/ Van Der Waal’s) forces

A

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

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13
Q

permanent dipole-dipole strength (what molecules)

A

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

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14
Q

permanent dipole-dipole

A

dipole-dipole permanent interaction in POLAR molecules

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15
Q

hydrogen bonding

A

not a bond - an intermolecular force

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16
Q

hydrogen bonding requirements

A

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

must have lone pair of electrons

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17
Q

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

A

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

18
Q

hydrogen bonding strength

A

strongest

19
Q

electronegativity trend down a group

A

decrease - shielding increase, atomic radius increase, less attraction

20
Q

electronegativity

A

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

21
Q

electronegativity across a period

A

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

22
Q

why do ionic compounds dissolve in water

A

ions for polar bonds with water molecules

23
Q

principle quantum number

A

shell number or energy level (n)

24
Q

solubility of ionic substances

A

generally soluble in polar solvents

25
Q

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

A
  • lattice must be broken down

- solvent molecules must attract and surround ions

26
Q

trend in ionic solubility as ionic charge increases

A

decrease

27
Q

solubility depends on…

A

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

28
Q

electrical conductivity of ionic substances

A

solid = unconductive

liquid/in solution = conductive

29
Q

covalent bonding

A

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

30
Q

covalent molecule

A

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

31
Q

why do more bonds often = more stable

A

as energy released when bonds made, so becomes more stable

32
Q

factors affecting electronegativity

A
  • nuclear charge
  • atomic radius
  • shielding
33
Q

element with highest electronegativity

A

fluorine

34
Q

intermolecular forces in molecule with no polar bonds

A

van der Waals

35
Q

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

A

van der Waals

36
Q

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

A

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

37
Q

non-polar covalent bond

A

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

38
Q

polar covalent bond

A

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

39
Q

solubility of non polar substances in polar solvents

A

insoluble/slightly soluble

40
Q

solubility of non polar substances in non-polar solvents

A

usually soluble - intermolecular forces form between solvent and solute molecules

AL. OCR Chemistry (20 decks)

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