Unit 1.2 - Basic ideas about atoms Flashcards
What is radioactivity?
When an unstable atomic nucleus decays, it spontaneously forms a new element by emitting ionising radiation, like alpha, beta or gamma
What is an alpha particle?
Helium nucleus
Alpha particle charge?
2+
Alpha particle relative mass
4
Alpha symbol
4
a
2
What is a beta particle?
An electron
Beta particle relative charge
-1
Beta particle relative mass
(about) 0
Beta symbol
0
B
-1
What is a gamma wave?
Electromagnetic wave
What is a gamma waves relative charge?
0
What is a gamma waves relative mass?
0
Gamma symbol
0
Y
0
Alpha penetrating power
Stopped by paper
Beta penetrating power
A few mm’s of aluminium
Gamma penetrating power
Decreased by a few cm’s of lead of concrete
Which type of radioactive particle is the most ionising and which is the least?
Most - alpha
Least - gamma
What is nuclear decay?
When a radioisotope decays, forming a new element, meaning its properties can be deduced
What decays for radioactivity?
Unstable atomic nucleus
What decays for nuclear decay?
Radioisotopes
What happens during gamma radiation? Why?
No new element is formed as it’s only emitted when an atom loses energy
When is gamma radiation emitted?
When an atom loses energy
What happens when alpha particles undergo nuclear decay?
Emits a helium nucleus (2 protons and 2 neutrons)
What happens to the mass and atomic number of the nucleus when undergoing the decay of alpha particles?
Mass number - loses four units of mass number
Atomic number - loses 2 units
How do you figure out which one is the new element after one has undergone nuclear decay of alpha particles?
2 places to the left on the periodic table
When is a high energy beta electron formed?
When a neutron decays into a proton and an electron
What happens when beta particles undergo nuclear decay?
The nucleus decays and emits a high-energy electron, which is formed when a neutron decays into a proton and an electron
What type of electrons are beta particles?
High energy
What happens to the mass and atomic number during the nuclear decay of beta particles?
Mass number - the same
Nuclear number - 1 more
How do you find out what the new element is once nuclear decay happens to beta particles?
One place to the right on the periodic table
Name 5 types of nuclear decay
-Gamma radiation
-Alpha particles
-Beta particles
-Electron capture
-Positron emission/beta plus decay
What uses electron capture and why?
Unstable atoms use to become more stable
How does electron capture work?
-Electron from the atom’s inner shell is drawn to the nucleus
-Combines with a proton
-Becomes a neutron and a neutrino
-Neutrino is ejected from the atom’s nucleus
Example of electron capture
Carbon 11 Boron 11
6 protons +electron ———> 5 protons + neutrino
5 neutrons 6 neutrons
What type of radioactive decay can have two possible names? What are they?
Positron emission or beta plus decay
What is the proton inside originally for positron emission/beta plus decay?
Radionuclide nucleus
How does position emission/beta plus decay work?
-Radioactive decay
-Proton inside a radionuclide nucleus is converted into a neutron while releasing a positron and an electron neutrino (Ve)
Electron neutrino symbol
Ve
What’s important to remember when writing equations involving nuclear decay?
The sum of the mass numbers on the reactants equals the sum of the mass numbers of the products
Why is radiation dangerous?
Can ionise and kill cells, and ionising molecules of living cells damages them, increasing cancer risks
Can also cause changes in the DNA, leading to mutations and cancer causing cells
What do changes in our DNA from radiation lead to?
Mutations and cancer causing cells
What does most of our annual radiation come from? How much?
80% - natural sources (radon especially)
What’s the main radioactive natural source that we’re exposed to?
Radon gas
What type of particles ionise cells the most?
Larger ones
What type of particles ionise cells the most?
Larger ones
Why are larger radioactive cells more dangerous?
They ionise more
Is alpha or beta the most dangerous? How come?
Alpha as the particles are larger
What, in terms of half life, makes a radioactive substance more dangerous? What factors does this effect?
Longer half life = more dangeous to environment
Shorter half life = more dangerous to living cells
What’s important to remember when calculating the electrons in an ion?
That it’s lost/gained some and it’s no longer equal to the protons
Which radioactive particle has the smallest defective angle and why?
Alpha as its mass is higher = it’s heavier
How do you work out the new element from electron capture?
1 place to the left on the periodic table
How do you work out the new element from positron emission / beta plus decay?
1 place to the left on the periodic table
Positron symbol
0
e
+1
5 uses of radioactivity
-Radiotherapy
-Carbon dating (carbon 14)
-Smoke alarms
-Medical tracer
-Thickness monitoring
Do we copy mass numbers straight from the periodic table with radioactive decay equations?
No- copy the element, but make sure the mass numbers match for that question (might be a bit different from the one on the periodic table)
Half life
The time taken for half the atoms in a particular amount of isotope to decay
4 characteristics of the half life of radioisotopes
-Own rate of decay
-Characteristic half-life
-Independent on the number of atoms present at the beginning
-Unaffected by changes in temperature
How would you work out the fraction left of a radioactive substance?
Time
——— (halve how ever many times this is)
half life
How do you work out a radioactive substance’s half life?
How many half lives required to reach this?
time
——
this
What happens when an electron encounters a positron?
They annihilate eachother, creating gamma radiation
What type of nucleus is the electron drawn to of for electron capture to happen?
proton-rich
What type of radiation does electron capture emit?
Gamma radiation
What does gamma have a high?
-Frequency
-Energy
Why are alpha particles the most ionising?
High positive charge to strongly attract electrons
Why does gamma have the least ionising power?
Short wavelength
Which side of the equation do we show the electron loss during electron capture?
The left side, the rest on the right
Why are atoms ionised?
Due to an electron being removed
What does a cancerous cell do?
Divide uncontrollably
What is the formation of tumours as a result of radiation an example of?
The late effect
What is cell death as a result of radioactive exposure an example of?
Acute effect
Acute effect
Happens rapidly after radioactive exposure (eg- cell death)
What type of radiation is the most dangerous INSIDE the body and why?
Alpha as it’s the most ionising
What type of radiation is the most dangerous OUTSIDE the body and why?
Beta and Gamma as they penetrate dead cells on the surface and damage living cells underneath
What does the radioactive source used for medical tracers require and why?
- A short half life to avoid permanent damage
-Emits enough radiation to be detected outside of the body
What type of radiation is used for radiotherapy and thickness monitoring?
Beta radiation
Electronic configuration
The arrangement of electrons in an atom
What type of energy do electrons have?
Fixed energies
Where do electrons move around?
In their shells/energy levels
What’s another word for the shells of electrons?
Energy levels
What’s the name for the numbers of electron’s shells?
Principal quantum numbers
What do different shells have?
Different amounts of energy
Which shell has the lowest amount of energy? Which electrons are these?
Level 1- electrons closest to the nucleus
What do electrons in different areas have?
Different orbitals
Orbital
A region in the space of a cloud of negative charge where you’d likely find an electron
What can orbitals hold?
Up to 2 electrons with opposite spin
Why do the orbitals hold electrons with opposite spin?
In order to stop them totally repelling eachother
What do orbitals have different?
Energies and shapes
What are the two orbitals whose shapes I need to be able to recognise?
S and P
Shape of the S orbital
Spherical
Shape of the P orbital
Dumb- bell
Draw the S orbital
lol go check your notes i’m not paying for premium
Draw the P orbital
(check notes)
What are shells divided into?
Sub shells
Which shell isn’t divided into sub shells?
1st
What do sub shells contain?
A specific number of electrons
Number of orbitals and electrons in the S subshell (how do you know?)
1orbital, 2 electrons (count across the elements in their groups- this is the electrons, and the orbitals is half this as each one holds 2 electrons)
Number of electrons and orbitals in the P subshell
Orbitals- 3
Electrons -6
Number of orbitals and electrons in the d subshell
Orbitals- 5
Electrons - 10
How do we write out electronic configurations?
-Look at the periodic table - we have an an s, p and d block
-Write out in full, the big number is the number of that block followed by the letter and the amount of elements in indices until you reach it (eg- 1s2, 2s2, 2p6, 3s2, 3p4 etc
How do we write shorthand electronic configurations?
The noble gas before and only the last bit- the electrons in the outer shell
Where are the noble gases on the periodic table?
Group 0, downwards
Why do we only write the electrons in the outer shell when writing electronic configurations short hand?
These are the only electrons that take part in chemical reactions
What do we write first, the 3 or 4 block? Which fills first?
The 4s block fills first, but you write however many 3s first
With the 4s block and a non-full 3d block, what do you do when writing shorthand electronic configurations?
Show the electrons in the d subshell too as they can be involved in chemical reactions
What’s the first row of the d block?
3d
Which block is helium part of?
The s block
3 electron shell filling rules
- Electrons are placed in a shell with the lowest energy
- Only 2 electrons can occupy an orbital and they have opposite spins
- The electrons are placed in a subshell with parallel spins until the subshell is half full
Which shell are electrons placed in?
The one with the lowest energy
What are electrons placed in? Until when?
In a subshell with parallel spins until the subshell is half full
How many electrons can occupy an orbital and what do they have?
2, opposite spins
Which directions are the different p orbitals?
Px- sideways
Py - diagonal
Pz- upwards
What do the arrows with the electron structures represent? Why is this?
Opposite spins that make it stable
Once we reach a certain orbital when writing out the electrons in their boxes, there’s a rule to remember. Which orbital is this and what’s the rule?
P orbital - half full them with just up arrows until full before filling with down arrows
Which two elements have a specific exception when filling in the electron boxes? What is this exception?
Chromium and copper
Need a half filled 4s box before filling the 3d box to be stable
(Chromium- full of ups)
(Copper - full of ups and downs)
What sort of half life would machinery like a medical tracer need and why?
Longer so that it doesn’t constantly need replacing
Why do we have to half full the 4s box before filling the 3d box with chromium and copper?
The 3d orbital becomes lower in energy than the 4s orbital when filled (breaks rule no.1)
Why is 4s filled before 3d?
Because it is of lower energy
How do you write the electronic configurations of ions?
-Write it as normal
-+ charge = take away that many electrons from the subshell with the highest energy (the last in the list)
(opposite for negative charge)
Where do we take away/add electrons for ions electronic configurations?
The subshell with the highest energy (the last in the list)
With ions in the d block, where are electrons lost first and why?
From the 4s subshell before the 3d as when the 4s subshell contains electrons, it has higher energy levels than the 3d subshell
Which one has the lowest energy - an empty 4s or an empty 3d level? What does this mean?
4s is lower so it’s filled first
Ionisation energy (I.E.)
The energy required to remove one or more electrons from an atom
(There’s a value of the ionisation energy for every electron in the atom)
What is there a value of for every electron in the atom?
Ionisation energy
What does I.E. stand for?
Ionisation energy
Molar first ionisation energy
The energy required to remove one mole of electrons from one mole of its gaseous atoms to form one mole of gaseous ions
What do you call the first ionisation energy?
Molar first ionisation energy
Under what conditions is the ionisation energy of an electron at the standard molar first ionisation energy?
The standard conditions…
298K
1 atmosphere pressure
What are the standard conditions and what do they cause?
298k and 1 atmosphere pressure cause the ionisation energy to be at the standard molar first ionisation energy
What type of reaction is the first ionisation energy and why?
Requires energy = endothermic
Is the first ionisation energy exothermic or endothermic?
Endothermic
What are energy changes measured in?
kJ mol-1
What causes variation in the standard molar first ionisation energy? What’s the phrase for this?
Outer electrons do not feel the full force of the positive charge of the nucleus, as the inner electrons screen them partially from its effects = screening
Screening
Outer electrons do not feel the full force of positive charge from the nucleus as the inner electrons screen them partially from its effects
What does screening cause variation in?
The values of standard molar first ionisation energy
What do successive ionisation energies provide information about?
The arrangement of electrons around the nucleus
Second ionisation energy
The energy required to remove one mole of electrons from 1 mole of 1+ ions to form 1 mole of gaseous 2+ ions
(same definition as you go up the ionisation energies, just it increases each ion charge by 1)
What provides us with information about the arrangement of electrons around the nucleus?
Successive ionisation energies
What does the value of the first ionisation energy depend upon?
- Nuclear charge (i.e -number of protons)
- Outer electron distance from the nucleus
- Screening produced by filled inner energy levels
What tells us the nuclear charge of an element?
Number of protons
As we move across the period, what happens to the ionisation energy?
Increases
Why does ionisation energy increase as we move across the periods?
- Nuclear charge increases
-Electrons are added to the same shell, therefore there’s no effect on screening
-More energy is required to remove them from the atom as the outer electrons are drawn closer to the nucleus across the period
What happens to the electrons as we move across the period?
The outer electrons are drawn closer to the nucleus, making them more strongly attached
For which elements would ionisation energy peaks appear on a graph?
Group 0 (noble gases)
For which elements would troughs appear on an ionisation energy graph?
Group 1
What are the two exceptions across the period for ionisation energies?
- Be to B and Mg to Al
- N to O and P to S
Why are Be to B and Mg to Al exceptions to the rule that ionisation energy increases across the period?
Although Boron has an extra proton, there’s additional screening by a full 2s level and less energy needed to remove Boron’s 2p electron, therefore its a decrease in ionisation energy.
(same concept for Mg to Al but with 3s and 3p)
What does a decrease in ionisation energy show on a graph?
Dips
Why are N to O and P to S exceptions to the rule that ionisation energy increases across the period?
With oxygen, the new electron goes into an orbital which already has an electron, meaning that there’s increased repulsion between 2 electrons of the same orbital, making it easier to remove an electron
(same concept for P to S)
This outweighs the effect of the extra proton
What happens when am electron goes into an orbital which already has an electron?
Increased repulsion between them
What happens to the ionisation energy as you go down the group?
First ionisation energy decreases
Why does the first ionisation energy decrease as you go down the groups?
Although there’s an increase in nuclear charge, there’s extra screening
Describe hydrogens ionisation energy and give a reason why it’s like this
High, as it contains a single electron that’s close to the nucleus and strongly attached without screening
Compare helium’s ionisation energy to hydrogen’s and give reasons for why you say this
It’s much higher, as similarly, the electron being removed is close to the nucleus and unscreened, however now the nucleus has 2 protons attaching the electrons instead of 1
Describe the ionisation energy from helium to lithium and give reasons why you say this
In lithium, the outer electron is in the second energy level, further away from the nucleus, and the additional proton in the nucleus is outweighed by the screening given by the 1s electrons, therefore the ionisation energy decreases
What is the nuclear charge?
The number of protons
What do we have to make sure we write in ionisation energy formulas and why?
(g) as we can only ionise gas
What’s screening caused by?
Full shells
Which outweighs which - shielding or nuclear charge? What does this mean?
Shielding effect outweighs the increase in nuclear charge, which is why the first ionisation energy decreases going down the periodic table
What is successive ionisation energy?
To successively remove all of the electrons until they’ve all been removed
How many successive ionisation energies does an element have?
As many as it has electrons
What’s a useful tip to remember when writing successive ionisation equations?
Whatever it’s labeled as is the target
e.g - third ionisation energy magnesium
Mg2+ (g) ——> Mg3+ (g) + e-
What do successive ionisation energies do?
Always increase
Why do successive ionisation energies always increase?
-Greater effective nuclear charge (same number of protons holding less electrons)
- Each one removed means less electron-electron repulsion so the shell is drawn closer to the nucleus
-The distance from the nucleus decreases so the nuclear attraction increases
What number can we click on the calculator to make ionisation energies smaller?
log
What is electromagnetic radiation?
Energy that can travel as waves + pass through a vacuum
List the types of radiation on the electromagnetic spectrum
Radio
Micro
Infrared
Visible
Ultra violet
X-ray
Gamma
What happens to energy, frequency and wavelength as you travel up the electromagnetic spectrum?
Increasing energy + frequency
Decreasing wavelength
Equation linking wavelength and frequency
c= ŷ(upside down y)f
where
c - speed of light (constant)
upside down y - wavelength
f - freqency
Equation for the energy of radiation
E = hf
where
E - energy
h - Planck’s constant
f - frequency
Energy unit
J
Wavelength unit
m
Speed of light unit (why?)
ms-1
because…
c = wavelength x frequency
frequency unit - s-1
wavelength unit - m
What’s the relationship between energy and frequency? Write this as a formula and give an example
Energy is directly proportional to frequency
E 🐟 f
(double frequency, double energy)
What’s the relationship between wavelength and frequency? Write this an as equation and give an example
frequency is indirectly proper optional to wavelength
f 🐟 1
—
upside down y
double wavelength, halve frequency
Wavelength + unit
Distance between one point on a wave to the same point in the next (usually the crest)
M
What is wavelength usually measured on?
The crest
Frequency + units
Number of waved produced by a source per second
Hz
How do you deal with units/prefixes?
Multiply the number in THAT form with the prefix
e.g
1mj—> ? J
milli prefix is 10-3
1x10-3 = 0.001J
what does the c symbol stand for?
centi
What does the T symbol stand for?
Tetra
Centi prefix
10^-2
Tetra prefix
10^12
What is light?
The visible region of the E-M spectrum
What’s the wavelength range of visible light?
700nm-400nm
What happens when you pass white light through a prism?
Split into a rainbow of colours known as the continuous spectrum
Which has the highest energy - blue or red light? Why?
Blue as it has the highest frequency
Emission line spectrum
elements are heated and give off light of certain wavelengths - seen as lines only on those specific wavelengths (the mostly black one)
What type of gas would cause the emission line spectrum?
Hot
What causes the emission line spectrum in terms of electrons?
Electron emits energy + drops down to ground level, releasing a photon of light
Absorption line spectrum
All atoms and molecules absorb light of certain wavelengths - if white light is passed through the vapour of an element, it was absorb certain wavelengths= black lines corresponding (mostly rainbow one)
What type of gasses are responsible for the absorption line spectrum?
Cold
What does white light have to do to absorb certain wavelengths?
Pass through the vapour of an element
What happens when white light passes through the vapour of an element?
Absorbs certain wavelengths of light
What causes an absorption line spectrum in terms of electrons?
Electron absorbs energy + gets excited to a higher level
What can both the emission and absorption line spectrums tell us?
Tell us about the arrangement of the electron shells in an atom by detecting the presence of particular elements, which all have a unique pattern due to different nuclear charges hence the arrangement of shells
Why do different elements have different patterns?
Differing nuclear charges hence the arrangement of shells
What do spectrometers and prisms do?
Separate light into its constituent frequencies
What separates light into its constituent frequencies?
Spectrometers and prisms
What do the excited states do as you move up them?
Converge (get closer)
Which energy state has the lowest energy and why?
The ground state as it’s the one closest to the nucleus
What do you call the numbers for all the excited states?
Quantum numbers
What’s important to remember with quantum numbers?
There’s no zero
What’s the word for an electron “jumping” to a higher energy level?
Being promoted
Explain how an electron is promoted
Atom is heated/put in an electric field
Electrons absorb energy
Become “excited”
Can jump to a higher energy level
What has to happen to an atom for electrons to absorb energy?
It has to be heated or put in an electric field
What does it take to promote an electron to a higher energy level?
A specific amount of energy
What is the energy absorbed by an electron equivalent to?
The amount needed for the jump = the line in the absorption spectrum
What IS the line in the absorption spectrum?
The amount of energy absorbed as it’s needed for an electron to jump
What does the frequency of the line on the absorption spectrum correspond to?
The specific energy needed
(E🐟f)
What does each line on the absorption spectrum correspond to?
A different jump between levels
What can you call the “jumps” of an electron?
Electronic transitions
What causes the emission spectrum in terms of electrons?
Energy is removed
Electrons fall from their excited state
Release that specific amount of energy, known as a quantum of energy/a photon
What is required for electrons to fall from their excited state?
Energy to be removed
What do you call the specific amount of energy released by an electron as it falls from its excited state?
A quantum of energy/photon
What’s the phrase for electrons being constrained to energy levels?
Quantised
What does the fact that electrons are quantised mean?
They’re constrained to energy levels
Because electrons are quantised, what do they do?
Emit specific photons of energy with discrete frequencies, causing sharp lines on the spectrums
How do you calculate the energy taken in/given out by an electron?
The difference between energy levels
(can use the frequency formula after this if asked for frequency)
What do you call 1s, 2s, 2p etc…?
Sub shells
What does the visible atomic emission spectrum of hydrogen do?
Provides evidence for the theory that electrons are found in definite energy levels around the nucleus of an atom
How do we obtain the visible atomic emission spectrum of hydrogen?
We use an electric discharge tube
What does an electric discharge tube have in order for it to obtain the emission spectrum of hydrogen?
-Hydrogen gas of low pressure in the tube
-High potential difference across the electrodes
-High voltage supply
Draw and label an electric discharge tube
check your notes lol
What happens to hydrogen within an electric discharge tube?
Hydrogen molecules are split into atoms, and when the electrical discharge passes through the tube, electrons are promoted to higher energy levels, and when they fall back down to a lower level, energy is released as electromagnetic radiation
Draw the visible atomic emission spectrum of hydrogen
check your notes
What energy level does the violet stripe in hydrogens visible atomic emission spectrum fall from and down to?
n=6 to n=2
What energy level does the dark blue stripe in hydrogens visible atomic emission spectrum fall from and down to?
n=5 to n=2
What energy level does the blue stripe in hydrogens visible atomic emission spectrum fall from and down to?
n=4 to n=2
What energy level does the red stripe in hydrogens visible atomic emission spectrum fall from and down to?
n=3 to n=2
What do you call the visible atomic emission spectrum of hydrogen?
The Balmer series
What energy level do all of the electrons in the Balmer series fall to?
n=2
What’s the name of the limit point on the visible atomic emission spectrum of hydrogen?
Convergence limit
Which colour is closest to the increasing frequency on the Balmer series?
Violet
What does the Balmer series contain?
A number of coloured lines on a black background
What do the lines on the Balmer series do?
Converge with increasing frequency
Converge
To tend to meet in a point or line
What happens to the energy levels and successive lines in the spectrum with increasing distance from the nucleus?
-Energy levels get closer
-Successive lines in the spectrum get closer
What are electrons found in and what is forbidden?
Definite energy levels, energies between are forbidden
What happens to an electron as it gains energy?
It’s promoted to higher levels
What happens when electron falls to a lower energy level?
Energy is emitted as EMR - a photon of light
Describe the difference in energy between any two levels in an atom
Fixed
Electron releases electromagnetic radiation unique to that transition, which is observed as a distinct line
What is the EMR released by an electron observed as?
Distinct lines
What makes the successive lines in the spectrum get closer?
With increasing distance from the nucleus, the energy levels get closer
When has ionisation occurred?
When an electron is promoted from the first energy level to convergence
When an electron is promoted from the first energy level to convergence, what has occurred?
Ionisation
What is the ionisation energy of hydrogen?
The energy needed to transfer the electron from e=1 to e=♾️
In which series does the the transition of hydrogen from e=1 to e=♾️ in order to ionise occur?
The Lyman series
How do you calculate the ionisation energy of hydrogen?
E=hf
where f is the frequency of the convergence line in the Lyman series
What is f in the E=hf formula for the ionisation energy of hydrogen?
the frequency of the convergence line in the Lyman series
Which successive ionisation energy is the lowest and why?
The first as it’s the furthers from the nucleus
Why is it unlikely that stable compounds containing Ba3+ ions exist?
-Barium is in group 2 and has 2 outer electrons
-Too much energy is needed to remove a third electron
-This necessitates removing an electron from a shell closer to the nucleus (to form a Ba3+ ion)
Wave particle duality
Electrons can act like waves and particles
What’s the phrase that expresses that electrons can act like waves and particles?
Wave particle duality
What are the colours of the stripes on the Balmer series?
violet, dark blue, blue and red
Which band has the highest amount of energy in the Balmer series?
Violet
Which band has the highest wavelength in the Balmer series?
Red
What’s it important to do when writing the arrows on a diagram showing how the spectrums arise?
Show their DIRECTION
What do we know if an electron falls to n=1 on the hydrogen emission spectrum?
It’s part of the Lyman series
What energy equations do we use when given frequency vs when given wavelength?
Frequency
E= hf
Wavelength
E= hc
—
upside down y
Which series has the lowest wavelength?
Lyman series
How do we calculate the first IE of an element in kJmol-1?
2 ways…
Either use E= hc
—
upside down y
Or
E=hf
(which you’d then have to use f=c
—
upside down y
for)
What’s important to remember to do when calculating the first IE of an element in kJmol-1?
-change nm to metres
-change J to Jmol-1 (multiply by Avogadro constant)
-change Jmol-1 to kJmol-1 (divide by 1000)
How do you get a unit in mol-1?
Multiply by Avogadro constant
Why can atoms only emit certain definite frequencies of visible light?
-They energy levels are fixed/quantised
-Electron falls from higher energy levels
What does the convergence limit of the Lyman series represent?
ionisation of the atom
Why do the lines within each series of emission spectrums converge?
Energy difference between the shells decreases/energy levels get closer together
How do you determine the group from successive ionisation energy?
-Look for a significant jump in IE - from an inner principal quantum shell
-Whichever one it’s jumped from = the group (e.g - 2nd = group 2)
How do you identify an element from successive ionisation energies?
Electrons before the jump are valence electrons (the electrons in the outer shell)
= find the elements with that valence
Valence
The electrons in the outer shell
Eg - Sodium valence = 1
(2,8 electrons used in first two shells, one left (atomic number of 11))
Draw and label an electric discharge tube
(Check notes)
What’s it important to remember with the penetrating power of gamma waves?
Concrete and lead only decreases it, not stop it
What is an alpha particle?
A helium nucleus (key word - nucleus)
What does having the greatest nuclear charge mean in terms of ionisation energy?
Has the largest last ionisation energy as the nucleus has the greatest charge to the last electron
What does ionisation involve?
A transfer of energy from the radiation passing through that matter to the matter itself
How do we calculate the maximum number of electrons we can fit in a shell?
2n squared, where n is the principal quantum number (the number of the shell)
Principal quantum numbers
The numbers of the shells on an atom
The distance of WHAT from the nucleus affects the first ionisation energy?
The outer electron
What does an electron emit when falling down an energy level?
Electromagnetic radiation
Describe the emission spectrum of hydrogen
-Coloured lines (violet, dark blue, blue, red) on a black background
-The lines converge with increasing frequency/energy
Whats special about the Balmer series?
All lines can be seen in the visible part of the electromagnetic spectrum
How can the atomic emission spectrum of hydrogen be used to determine a value for its ionisation energy?
E = hf
(Where f is the frequency of the convergence limit in the Lyman series)
How do we convert from J to kJmol-1?
- X NA (Avogadro constant) - Jmol-1
- Divide by 1000 - kJmol-1
What is radioactive decay?
The process that takes place when an unstable atomic nucleus loses energy by emitting radiation
What is alpha decay?
A type of radioactive decay, during which an atomic nucleus loses two protons and two neutrons.
An alpha particle is equivalent to a helium nucleus.
Makes an element more stable by reducing the atomic number by 2 and the mass number by 4.
Why is gamma radiations ionising power so low compared to alpha and beta?
Short wavelength
Alpha particle range in air
Less than 5cm
Beta particles range in air
Less than 1m
Gamma wave range in air
Infinite
Which type of electromagnetic radiation has an infinite range in air?
Gamma wave
What’s a sub shell?
A division of electron shells separated by orbitals
(S, p d and f)
What determines the chemical properties of an element?
Its electronic configuration
Whats does electronic configuration determine for an element?
Its chemical properties
Why does alpha radiation have the highest ionising power?
High positive charge
How do beta particles ionise an atom?
Collides with the electron and knocks it out of the atom
What type of radiation is often used in medical tracers? Why?
Gamma, as they can easily penetrate through the skin and aren’t very ionising + not as easily absorbed by cells as alpha radiation
What actually are the 70, 72 and 74 numbers in the mass spectrum of chlorine? What does this mean?
Unified atomic mass units (u)
1u = the mass of 1/12 of the carbon-12 atom
What does the fact that electrons are quantised mean for them?
-Sharp lines on the spectrum
-Emit discrete frequencies of light
What do I need to ensure I’m doing enough of when answering ionisation energy questions?
Making references to specific subshells
Why do the first row of d-block elements have a similar 1st ionisation energies?
-Electron removed comes from the 4s orbital
-As you add an extra proton to the nucleus, you add an extra electron to the 3d orbital, screening the affect of the extra proton
Why is zinc’s first ionisation energy significantly higher than copper’s?
-Electron removed comes form the 4s orbital with a complete 3d level inside = equal screening
- Increase = attraction of the extra proton in the nucleus
What is labelled as “y” on an orbital diagram?
The direction the orbital is facing
Why do the mass numbers not change on isotopes undergoing radioactive decay by beta emission or electron capture?
Involves electrons with very little mass
What do we do when showing the defective angle of a positron in an electrical field?
Attract it towards the negative side, similar to the beta one (only in the other direction) if it’s present
What loses energy for gamma radiation to be emitted?
An atom
Which way would the arrows face on the energy level diagram for an absorption spectrum?
Upwards
Which way would the arrows face on an energy levels diagram for an emission spectrum?
Downwards
What do we need to remember to do when writing equations for first ionisations?
-Include state symbols
-Put the electron on the right hand side of the equation
-Whatever labelled as = target
Where do you remove the electron from first with the d block elements?
The 4s orbital
What must we remember to include in the definition of molar first ionisation energy when its “STANDARD molar first ionisation energy”?
Under STANDARD conditions
What is the whole system of a mass spectrometer under?
Vacuum
Which region of the electromagnetic spectrum is the lyman series in?
UV
Which orbital do we fill and empty first for transition metals?
4s
Why are there several series on lines in the hydrogen emission spectrum?
Each series corresponds to electrons falling to different energy levels
kJmol^-3 to J
X1000, divide by Na
