Fundamentals of Chemistry Flashcards

1
Q

what is the charge and mass of a proton

A

positive, and 1 amu

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2
Q

what is the charge and mass of a neutron

A

no charge, 1 amu

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3
Q

what is the mass and charge of an electron

A

negative, 0.0005458 amu

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4
Q

define ion

A

the number of protons does not equal the number of electrons

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5
Q

define isotope

A

same number of protons and electrons but a different number of neutrons

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6
Q

define pure substance

A

consists of atoms with the same number of protons, cannot be broken into simpler species

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7
Q

define compound

A

consist of more than one type of element and are held together by chemical bonds

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8
Q

define ionic compound

A

when a non-metal reacts with a metal and a transfer occurs. There is an electrostatic attraction between the opposite charges

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9
Q

properties of ionic compounds

A

high melting point and can conduct electricity when liquid

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10
Q

define molecular compound

A

covalent compounds where atoms share electrons, often non-metals

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11
Q

properties of molecular compounds

A

low melting and boiling points

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12
Q

define empirical formula

A

gives elements the smallest possible ratio

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13
Q

define skeletal formula

A

each carbon is represented by a line

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14
Q

define isomer

A

different molecules have the same formula but different connectivity

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15
Q

define chemical reaction

A

any process that leads to a chemical transformation of one or more substance into another

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16
Q

how many molecules does a mole contain

A

6.022x10^23

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17
Q

define attractive force

A

one that pushes things towards zero (makes them closer)

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18
Q

define repulsive force

A

pushes things away

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19
Q

define potential well

A

a dip in energy vs distance graph

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20
Q

define functional group

A

a part of a molecule which has distinctive chemical properties

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21
Q

IR light will only be absorbed when shone at a sample if…

A
  1. the energy of the radiation corresponds to the energy required to vibrate the molecule
  2. the vibration leads to the dipole moment of the molecule changing
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22
Q

what is the equation for electromagnetic radiation (speed of light)

A

wavelength x frequency

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23
Q

what is the equation for energy of a photon

A

plancks constant x frequency of a photon

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24
Q

define the Heisenberg Uncertainty Principle

A

we cannot simultaneously know the location and energy of an electron

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25
Q

define orbital

A

a region of the atom where an electron is most likely to reside

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26
Q

name the 4 different types of orbitals

A

different energies (n)
different shapes (l)
different orientations (ml)
different spins (ms)

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27
Q

what is n more commonly known as

A

the principle quantum number

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28
Q

what is l more commonly known as

A

the angular momentum quantum number (n-1)

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29
Q

what are orbitals with l=0 known as

A

s-orbitals

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30
Q

what are orbitals with l=1 known as

A

p-orbitals

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31
Q

what is an angular node

A

when the wave function changes sign, the point in the middle is 0, and this is an angular node, l

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32
Q

what are the values of ms

A

1/2 or -1/2

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33
Q

what did Pauli discover

A

no two electrons in the same atom can have exactly the same quantum numbers, they can share the same orbital provided ms is different, meaning there is a max of 2 electrons per orbital

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34
Q

list the orbitals from lowest to highest energy

A

s, p, d, f

35
Q

describe metallic bonding

A

valence electrons are a long way from the nucleus and not held tightly, multiple atoms can overlap without nuclei repelling, does not require close overlap, electrons can delocalise across the system and carry charge

36
Q

define power

A

the rate of change of energy

37
Q

give the equation for power

A

E/t (energy/time)

38
Q

define potential maximum

A

any change or movement will cause the energy to be lowered

39
Q

define potential minimum

A

extra energy is needed to move it away from the minimum (most stable positions)

40
Q

define Coulomb’s Law

A

the force between two oppositely charged objects depends on the size of the charges and varies inversely with the square of the distance

41
Q

if the overall charge is negative for Coulomb’s equation, is the force attractive or repulsive

A

attractive

42
Q

define binding energy

A

the energy given out by forming a bond

43
Q

define crystalline solid

A

ordered at the microscopic scale, with the component atoms or molecules packing in regular or repeating way all the way through the solid

44
Q

define cation

A

any ion with an overall positive charge

45
Q

define amorphous solid

A

not ordered and molecules are packed at random

46
Q

define anion

A

any ion with an overall negative charge

47
Q

define lattice enthalpy

A

the energy change which occurs when one mole of solid forms from ions which start out indefinitely far apart, and since the lattice forms and makes bonds, the system ends up lower in energy and so we represent that as a negative enthalpy

48
Q

define electronegativity

A

how much an element draws electrons towards itself

49
Q

define the Octet rule

A

each atom tries to adopt a state with 8 electrons in its highest energy level

50
Q

define the Bond-Oppenheimer approximation

A

electrons are small and can move quickly, whilst atomic nuclei are larger, heavier and do not move as fast, so we can regard the nuclei as static on the timeframe of electrons

51
Q

define quantum confinement

A

the phenomenon by which the more localised a particle is, the higher energy it is

52
Q

what are the limitations of the particle in a box model

A

atoms are not one dimensional, the electrostatic potential well for a Coulombic potential is not boxed shaped, and the atomic potential well is not infinitely deep as you are able to remove electrons from atoms

53
Q

define valence bond theory

A

bonds form when two atoms orbitals overlap and share two electrons between themselves

54
Q

how do we get in-phase combination

A

by adding two orbitals together

55
Q

how do we get out-of-phase combination

A

by subtracting one orbital from the other

56
Q

what does the in-phase combination show

A

constructive interaction

57
Q

What is the difference between in-phase and out-of-phase combination

A

in-phase: the space occupied by the electrons in the combined orbital is larger than the space occupied by the electrons in the two separate orbitals
out-of-phase: the space occupied by the electron is less than that of the free atoms

58
Q

define bonding orbital

A

the in-phase combination which produces an orbital lower in energy than the original orbitals

59
Q

what is the equation for bond order

A

1/2 (number of electrons in bonding orbitals - number of electrons in anti-bonding orbitals)

59
Q

isoelectric relationship

A

two compounds with different atoms and charges have the same number of electrons in the same type of orbital

59
Q

define anti-bonding orbital

A

an out-of-phase combination which is higher in energy than the original orbitals

60
Q

what are the rules for filling MO diagrams

A

fill from the lowest energy up
for orbitals of the same energy, electrons fill up first with spins parallel, then anti-parallel pairing

61
Q

define orthogonality

A

two orbitals can occupy the same space but never form bonding or anti-bonding combinations with each other

62
Q

define sigma symmetry

A

if you rotate around the axis of the atom then everything stays the same

63
Q

define pi symmetry

A

if rotate around the axis and the wave function changes

64
Q

define inversion symmetry

A

if (+x, +y, +z) and (-x, -y, -z) are equal and opposite

65
Q

what is the label we give something if it has inversion symmetry

A

u, meaning ungerade

66
Q

what label do we give something if 𝛹(+π‘₯, +𝑦, +𝑧) = 𝛹(βˆ’π‘₯, βˆ’π‘¦, βˆ’π‘§)

A

g, for gerade

67
Q

define paramagnetic

A

compounds with unpaired electrons

68
Q

define diamagentic

A

compounds with paired electrons

69
Q

define s-p mixing

A

when the s and p orbitals on adjacent atoms can interact if they point towards each other

70
Q

define molecular orbital theory

A

the true MOs of a molecule are formed by LACO (linear combination of AOs) and are determined by considering all of the AOs at once rather than only considering pair-wise interactions

71
Q

define local orbital approximation

A

the idea that only nearby things will significantly affect the local environment

72
Q

define conjunction

A

used to describe the situation when pi systems are β€˜linked together’

73
Q

define hybridization

A

the concept of mixing atomic orbitals to form new hybrid orbitals suitable for the pairing of electrons to form chemical bonds in valence bond theory

74
Q

describe how to determine hybridization of an atom in a molecule

A
  1. Count the number of atoms (not bonds) connected to it
  2. Count the number of lone pairs attached to it
  3. Add these numbers together
  4. If it’s 4, the atom is sp3
  5. If it’s 3, the atom is sp2
  6. If it’s 2, the atom is sp
  7. If it’s 1, it’s probably hydrogen
75
Q

define resonance stabilisation

A

the kind of stabilisation through delocalisation into conjugated systems

76
Q

why is the kekule structure incorrect

A
  • It predicts alternating short and long bonds, but all measurements are actually the same
  • Double bonds react rapidly with Br2 as this is one of the common tests for alkenes, however benzene does not
  • It predicts that 1,2-disubstituted benzene should show two isomers, but benzene only shows one
  • Benzene is much more stable, thermodynamically speaking, than would be expected. It would be expected to be -406kJmol-1, but in reality it is -206kJmol-1
77
Q

what relationship must be true for a compound to be aromatic

A

π‘π‘œ. π‘œπ‘“ πœ‹ π‘’π‘™π‘’π‘π‘‘π‘Ÿπ‘œπ‘›π‘  = 4𝑛 + 2 (Huckel’s rule)

78
Q

what is the relationship for anti-aromatic compounds

A

they have 4n electrons

79
Q

how does photoelectron spectroscopy work

A

by ionizing samples using high energy radiation (UV or X-rays) and measuring the kinetic energies of the ejected electrons

80
Q

what does photoelectron spectrsocopy determine

A

the relative energies of electrons in atoms or molecules

81
Q
A