Advanced Higher Chemistry Unit 1

Front 1

How do frequency, wavelength, and energy change as you pass from one end of the electromagnetic spectrum to the other?

Back 1

As you pass from radio to gamma waves...
-frequency increases
-wavelength decreases
-energy increases

Front 2

What is the relationship between wavelength, frequency, and velocity?

Back 2

Velocity (c) = wavelength (lambda) x frequency (nu)

Front 3

What is wavelength? (lambda)

Back 3

The distance between adjacent crests of a wave. (m)

Front 4

What is frequency? (v)

Back 4

The number of complete waves that pass a point per second. (Hz)

Front 5

What is wave number? (nubar)

Back 5

The reciprocal of the wavelength, the number of waves per metre.

Front 6

How can electromagnetic radiation be described in terms of structure?

Back 6

As a stream of very small particles - packets of energy called photons.

Front 7

How is the energy of a photon calculated? A mole of photons?

Back 7

Energy of photon = Planck's constant x frequency (E = hv)

Energy of a mole of photons = (Avogadro's constant x Planck's constant x velocity) / wavelength (E = (Lhc / lambda)

Front 8

What is Planck's constant?

Back 8

6.63 x 10^-34 JHz^-1

Front 9

What is Avogadro's constant?

Back 9

6.02 x 10^23 mol^-1

Front 10

What is spectroscopy?

Back 10

The study of how light and matter interact.

Front 11

What happens when electromagnetic radiation interacts with matter?

Back 11

There is a transferral of energy.

Front 12

What are emission / absorption spectra?

Back 12

Individual elements have characteristic emission and absorption spectra that can be used for identification. Both involve the transition of electrons between energy levels. Emission concerns when an electron moves to a state of lower energy, emitting photons, and absorption concerns when an electron moves to a state of higher energy by absorbing photons.

Front 13

How is emission spectroscopy utilised?

Back 13

Light passed through an element can be passed through a grating to create a line spectrum that shows up as a characteristic number of discrete wavelengths. This is not a continuous spectrum as the particles can only emit specific frequencies which correspond to transitions of electrons from higher to lower energy levels.

Front 14

How is absorption spectroscopy utilised?

Back 14

White light passed through a sample of ground state particles will show black lines in an otherwise continuous spectrum. These correspond to the light that has been absorbed by the atoms in the sample (and also correspond to the coloured lines which would be produced in the emission spectrum of that element)

Front 15

What are quanta?

Back 15

Small, fixed amounts of energy that can be transferred between levels.

Front 16

What causes emission spectra?

Back 16

When excited particles return to the ground state by the movement of electrons to lower energy levels. The frequency of the line in the emission spectrum corresponds to the difference in energy between the two levels.

Front 17

What is the convergence limit?

Back 17

The further the rings are away from the nucleus, the higher the energy. As energy increases the levels become closer together until they converge. The convergence point corresponds to the ionisation energy.

Front 18

What are the Balmer and Lyman series?

Back 18

Excited electrons in the Lyman series fall to the n = 1 energy level and lines are produced in the UV region.
Excited electrons in the Balmer series fall to the n = 2 energy level and lines are produced in the visible region.

Front 19

What are the quantum numbers?

Back 19

Principle number (n)
Angular moment (l)
Spin quantum number (ms)
Magnetic moment (ml)

Front 20

What is the principle quantum number? (n)

Back 20

Each shell in an electron is numbered, with n = 1 being the one closest to the nucleus.

Front 21

What is the angular moment? (l)

Back 21

Gives the shape of the orbital. All s orbitals are spherical and all p orbitals are dumbbell shaped.
l = 0 in s orbitals
l = 1 in p orbitals
l = 2 in d orbitals
l = 3 in f orbitals

Front 22

What is the magnetic moment? (ms)

Back 22

Refers to the orientation in space of the orbital. Related to l in that it can take on any integer value from -l to +l.

Front 23

What is the spin quantum number? (ml)

Back 23

Determines the direction of spin.

Front 24

What is the Heisenburg uncertainty principle?

Back 24

It is impossible to define with absolute precision, simultaneously, both the position and momentum of an electron.

Front 25

What is the Pauli exclusion principle?

Back 25

No two electrons in an atom can have the same four quantum numbers.

Front 26

What is the Aufbau principle?

Back 26

Electrons fill orbitals in order of increasing energy.

Front 27

What is Hund's rule?

Back 27

When degenerate orbitals are available, electrons fill each orbital singly and with parallel spins before pairing up.

Front 28

What is the order of subshells? (Energy)

Back 28

1s 2s 2p 3s 3p 4s 3d 4p 5s ...

Front 29

How many electrons can be held in each type of subshell?

Back 29

s = 2
p = 6
d = 10
f = 14

Front 30

What are transition metals in terms of electron configuration?

Back 30

Those which have an incomplete d subshell in at least one of their ions.

Front 31

What is the oxidation state?

Back 31

Same as the value of the charge on an atom or ion.

Front 32

What is the oxidation state of oxygen?

Back 32

-2 except in hydrogen peroxide where it is -1

Front 33

What is the oxidation state of hydrogen?

Back 33

+1 except in the hydrides where is it -1.

Front 34

What is electro negativity?

Back 34

The ability of an atom in a molecule to attract shared electrons to itself.

Front 35

What are the intramolecular forces?

Back 35

Ionic and covalent bonds.

Front 36

What are covalent bonds?

Back 36

Shared pair of electrons found in the region of overlapping atomic orbitals.

Front 37

What is the molar bond enthalpy?

Back 37

The energy required to break one mole of chemical bonds to form atoms.

Front 38

What are polar molecules?

Back 38

Asymmetrical molecules that exhibit polar bonding, causing a permanent dipole.

Front 39

What are the intermolecular forces?

Back 39

Hydrogen bonding
Permanent dipole dipole interactions
Van der Waal's forces

Front 40

What are Van der Waal's forces?

Back 40

The temporary separations of charge that attract one non polar molecule to another.

Front 41

What is hydrogen bonding?

Back 41

Strong attractive forces between H and O, N or F.

Front 42

What are cations and anions?

Back 42

Cation - positive ion
Anion - negative ion

Front 43

What is the coordination number?

Back 43

The number of nearest neighbours to a particular ion.

Front 44

How does ratio of radius indicate structure?

Back 44

Approx 0.5 ratio indicates a face centred cubic arrangement such as in NaCl, 6:6.

Approx 1 ratio indicates a body centred cubic structure such as in CsCl, 8:8.

Front 45

What is hybridisation?

Back 45

The combining of two or more orbitals of nearly equal energy within the same atom into orbitals of equal energy.

Front 46

Why are metals good conductors?

Back 46

Because of their mobile delocalised electrons in the metallic lattice. Some metals are better conductors than others due to their low resistance to flow of electrons.

Front 47

What are superconductors?

Back 47

Materials that conducts electricity with no resistance and thus no loss of energy.

Front 48

Which metals act as superconductors at low temperatures?

Back 48

Mercury, copper, lead, tin and silver.

Front 49

How does resistance vary with temperature?

Back 49

As temperature increases...

The resistance in a superconductor increases.

The resistance in a semiconductor decreases.

Front 50

What is the Meissner effect?

Back 50

Electrical resistance is thought to decrease because the delocalised electrons pair up within the metallic lattice, resulting in the substance being diamagnetic (repels a magnetic field).

Front 51

How can superconductors be used?

Back 51

The Meissner effect can be utilised in MRI scans and frictionless transport. The low electrical resistance allows efficient power transmission and fast electronic processing.

Front 52

What are the metalloids?

Back 52

Semiconductors, for example silicon and germanium.

Front 53

How does conductivity in metals and metalloids vary with temperature?

Back 53

...

Front 54

How can conductivity in semiconductors be increased?

Back 54

Increased temperature and exposure to light.

Front 55

How do the bands in semiconductors work?

Back 55

In semiconductors the atomic orbitals group into bands. The valence band in a semiconductor is either empty or full and the electrons cannot move. When electrons are excited, they move into a higher band called the conduction band and this movement of electrons allows conduction to occur. In semiconductors the band gap between these bands is relatively small. In insulators it is large and in conductors the bands overlap.

Front 56

What is doping?

Back 56

The addition of small numbers of atoms with different numbers of valence electrons.

Front 57

What are n type semiconductors?

Back 57

Created by the addition of a group 5 dopant. The extra electron occupies the conduction band and carries the charge.

Front 58

What are p type semiconductors?

Back 58

Made through the addition of a group 3 dopant. Creates positive holes in the semiconductor which carry the charge.

Front 59

What is a p-n junction?

Back 59

The juxtaposition of p and n type semiconductor that results in electrons moving from the n to the p type material, creating a separation of charge and preventing further movement of electrons.

Front 60

What happens in a photovoltaic cell?

Back 60

When a p-n junction is irradiated with light, electrons migrate towards the n type semiconductor and the holes migrate towards the p type semiconductor. If the upper and lower layers are connected via an external circuit then the electrons flow from n to p to restore the balance of charge.

Front 61

What does amphoteric mean?

Back 61

Has both acidic and basic properties.

Front 62

What is a dative covalent bond?

Back 62

A covalent bond in which one of the atoms provides both the electrons that form the bond.

Front 63

Name amphoteric oxides.

Back 63

Al2O3, H2O, BeO

Front 64

What are the bonding structure and properties of oxides across the period?

Back 64

Bonding structure is ionic lattice until SiO2 which is covalent network. Those following are covalent molecular.

Basic on left until Al2O3, which is amphoteric, then acidic after.

Front 65

How do ionic and covalent chlorides react with water?

Back 65

Ionic - dissolve with no reaction
Covalent - fumes of HCl given off

Front 66

What are the bonding structures and properties of chlorides across the period?

Back 66

Ionic lattice until AlCl3, which is covalent molecular, and all following are also covalent molecular.

Soluble in water until AlCl3, at which point all following produce white fumes of HCl. Cl2 itself just dissolves to form an acidic solution.

Front 67

What are the bonding structures and properties of hydrides across the period?

Back 67

Bonding structure: NaH is an ionic lattice, MgH2 is an intermediate between ionic and covalent, AlH3 is polymeric, and all following are covalent molecular.

Goes from alkaline, to neutral at SiH4, to acidic. PH3 is insoluble.

Front 68

How does the hydride ion act?

Back 68

Acts as a reducing agent and a strong base and will remove a hydrogen ion from a water molecule.

Front 69

What are ligands?

Back 69

Molecules or ions in a complex that surround the central metal ion that attach to the central ion with dative covalent bonds.

Front 70

Why does nitrogen have a higher first ionisation energy than oxygen?

Back 70

Because nitrogen has a half filled p sub shell.

Front 71

Why can the wavelengths that ligands absorb change when the ligand changes?

Back 71

Different ligand field strength.

Front 72

How can you find the coordination number of a compound?

Back 72

Divide the radius of the positive ion by the radius of the negative ion. If the value is close to one, it should be 8:8. If it is close to 0.5, it should be 6:6.