Whats the atomic number?
5
What's the mass number?
11
How many protons does it have?
How many neutrons does it have?
6
Relative charge of a proton
+1
Relative charge of a neutron
0
Relative mass of a proton
1
Relative mass of a neutron
Relative mass of an electron
Atomic number =
Number of protons
Mass number =
Total number of protons and neutrons
Number of neutrons =
Mass - Atomic
What does a positive charge mean?
Number of lost electrons
What does a negative charge mean?
Number of extra electrons
Relative charge of an electron
-1
How many electrons does it have?
8
What does the charge mean?
It's gained 3 electrons
What is this called?
Nuclear symbol
How are electrons arranged?
In electron shells
Shells have …
Sub shells
What's each sub-shell made up of?
Electron orbitals which can hold 2 electrons which spin in opposite directions
What are orbitals?
Regions of space that electrons are most likely to be in
What does electron configuration determine?
Reactivity
What's Aufballs principle?
Electrons enter the lowest energy orbital available
What's Hunds rule?
Electrons prefer to occupy orbitals on their own and only pair up when no empty orbitals of the same energy are available
What's the order of filling orbitals?
1s² 2s² 2p⁶ 3s² 3p³ 4s² 3d¹⁰ 4p⁶
Are electrons lost from 4s or 3d first?
4s
Why are orbitals filled in numerical order?
Because principle energy levels get closer together as you get further from the nucleus
What did Bohr state about the atom?
Small nucleus of protons and neutrons surrounded by circulating electrons
Each shell/energy level could hold max number of electrons
Energy of levels become greater as for further from nucleus
Electrons filled energy levels in order
1st shell = 2
2nd shell = 8
3rd shell= 18
4th shell = 32
5th shell= 50
What happens to the electron configuration when ions are formed?
Highest energy electrons are most first
When simplifying e.c, what do you look at?
Nobel gases
What are the exceptions to the configuration re regarding 4s orbital?
Chromium
Copper
What changes in the electron configuration with chromium and copper?
4s orbital still filled before 3d but only occupied by 1 electron
Give the configuration of chromium
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d⁵
Give the configuration of copper
1s² 2s² 2p⁶ 3s² 3p⁶ 4s¹ 3d¹⁰
What factors affect I.E?
Nuclear charge
Distance from nucleus
Shielding
How does nuclear charge affect I.E?
The more protons in the nucleus, the higher the positive charge, so the stronger the attraction for the electrons
How does distance from nucleus affect I.E?
Attraction decreases with distance. An e- closer to the nucleus will be more strongly attracted that ones further away
How does shielding affect I.E?
An electron in an outer shell is repelled by electrons in complete inner shells, weakening the attraction to the nucleus
What's an isoelectronic ion?
Charged particle which has same number of electrons
How's the period table arranged?
By atomic number
Elements in same period …
Have same number of shells
Elements in same group…
Have same number of electrons in the outer shell so similar properties
What's the periodic table split into and why?
4 blocks to show which subshell outermost electron of element is in.
E.g 1s² 2s² 2p⁶ - in p block
What's ionisation energy?
Measure of the amount of energy needed to remove electrons from atoms
Why's there a great attraction between protons and electrons?
Electrons -vely charged and protons +vely charged
The greater the pull of the nucleus…
The harder it will be to pull an electron away from an atom
What's the first ionisation energy?
Energy needed to remove one mole of electrons from one mole of atoms in the gaseous state
1st I.E =
Remove 1st electron
2nd I.E =
Remove 2nd electron (not 2 electrons)
General equation for I.e
Why do neutral atoms and molecules need to be ionised?
To accelerate them
To deflect them to the negative plate
What are the 2 ways of ionising samples?
Electron impact ionisation
Electrospray ionisation
What are the stages of time-of-flight mass spectrometry?
Ionisation
Acceleration
Flight tube
Detection
What's a time-of-flight mass spectrometer used for?
Measuring the masses of atoms and molecules
Measure the relative abundance of different isotopes
To predict the structure of more complex molecules
What happens during electron impact ionisation?
Sample is bombarded with high energy electrons from electrongun. Knocks an electron off the atom/molecule to form a positive ion. The Ar/Mr of ion will be the same as the m/z recorded on the spectrum
What happens during electrospray ionization?
The sample is dissolved in a volatile solvent than injected through a needle at high today causing molecule to gain a proton (M + H+ →MH+)
Mr of molecule will be one less than me m/z value due to the added proton
What happens during acceleration?
Positive ions are accelerated using an electric field
All ions have same kinetic energy when accelerated by the electric field
KE =
½mv²
V=
√(2KE/m)
KE = ½mv²
KE in
m in
V in
Joules (J)
Kg
ms-¹
What happens in the flight tube?
Lighter particles move faster so have shorter time of flight
t =
d/v
t=d/v
t in
d in
Seconds
Meters
What happens during detection?
Positive ions hit a negatively charged electric plate
When hit plate, the positive ions are discharged by gaining electrons from the plate. This generates a movement of e-s and an electric current that can be measured
Size of current is relative to abundance of each isotope
What is relative atomic mass?
The average mass of an atom of an element compared to 1/12 the mass of an atom of carbon-12
How can relative atomic mass be measured?
Using time-of-flight mass spectrometer
What are isotopes?
Atoms with the same number of protons and electrons but different number of neutrons
Isotopes have the same …. number but different …
Atomic
Mass number
Isotopes have the same … why?
Chemical properties as have same electron configuration
Isotopes have slightly different … why?
Physical properties as this depends on mass
R.A.M =
Definition of relative atomic mass
When does ionisation energy increase?
Down a group and across a period
Why does ionisation energy increase down a group?
Outer electron further away from nucleus so weaker attraction between nucleus and outer electron
Outer electrons are in higher energy orbitals and so have more shielding weakening the attraction
Why is there a general increase in ionisation energy across a period?
Increasing number of protons so greater attraction between nucleus and outer electron
Electrons added to same shell so same shielding across period
Describe the trends in ionisation energy in period 3
General increase
Drop between group 2 (Mg) and group 3 (Al)
Drop between group 5 (P) in group 6 (S)
Why is there a drop in ionisation energy between magnesium and aluminium?
Outer electron in aluminium is in 3 p subshell
3p is higher in energy than 3s so weak attraction than in Mg
Why is there a drop in ionisation energy between phosphorus and sulphur?
Outer electron begins to pair in 3 p orbital in sulphur increasing electron repulsion, paired electrons repel
Is the first or second ionisation energy larger?
Second
Why is the second ionisation energy always larger than the first?
Takes more energy to remove an electron from a positive ion
When is there a large increase in ionisation energy?
When there's a change in shell (decrease in shielding)
Which has a higher ionization energy?
Helium or hydrogen
Helium
Lithium or helium
Beryllium or lithium
Beryllium
Boron or beryllium
Carbon or boron
Carbon
Nitrogen or carbon
Nitrogen
Oxygen or nitrogen
Fluorine or oxygen
Fluorine
Neon or fluorine
Neon
Sodium or neon
Describe the ionisation energy of hydrogen
Quite high as outer electron has no shielding
Electron close to nucleus so high attraction between nucleus and outer electron
Why does helium have a higher ionization energy than hydrogen?
Have same shielding as both outer electrons in 1S shell but helium has more protons so greater attraction between nucleus and outer electron which requires more energy to remove
Why does lithium have a lower ionisation energy than helium?
Outer electron in second shell so weak attraction as further from nucleus and shielded by 1S shell so requires less energy to remove
Why does beryllium have a higher ionization energy than lithium?
Outer electron in same (2s) shell so same shielding but greater attraction as has more protons
Why does boron have a lower ionization energy than beryllium?
Outer electron in 2p sub shell rather than 2s (in Li) which is higher in energy so requires less energy to remove
Why does carbon have a higher ionization energy than boron?
Same shielding but has more protons so greater attraction
Why does nitrogen have a higher ionization energy than carbon?
More protons so greater attraction with same shielding
Why does oxygen have a lower ionization energy than nitrogen?
Outer electron begins to pair in 2p orbital and the paired electrons repel requiring less energy to remove therefore lower ionisation energy
Why does fluorine have a higher ionization energy than oxygen?
Has more protons so greater attraction with same shielding
Why does neon have a greater ionisation energy than fluorine?
More protons so greater attraction between nucleus and outer electron with the same shielding
Why does sodium have a lower ionisation energy than neon?
Altura electron in 3rd shell compared to second shell in neon so weak attraction to nucleus and outer electron further from nucleus and more shielded (by 1s, 2s and 2p)
What's Avogadro's constant?
Number of atoms or ions on molecules in one mole of any substance
Avogadro's constant
6.022x10²³
How do you calculate the mass of one ion?
Convert mass of one mole of the ions into kg by /1000
Find mass of one individual ion by dividing by Avogadro's constant
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