chem atomic Flashcards
1661
Robert Boyle
Some supbstances can’t be made simpler
These are chemical elements
1803
John dalton
Elements composed indivisible atoms
Not broken down
Atoms same element have same mass
1896
Henri bewuerel
Radioactivity
Particles come from inside of atom
Not indivisible
Then jj
Electron
1911
Ernest Rutherford
Most mass and all pos charge of the atom was in tiny central nucleus
Proton mass
1
Neutron mass
1
Electron mass
1/1840
Protion charge
+1
Neutron charge
0
Electron charge
-1
Atomic number
Proton number
Z
Mass number
A
Protons + neutrons
Isotopes
Atoms of elements with same proton and electron numbers but diff neutron numbers
React chemical.y same way
Same configuration
Mass number varies due to diff neutrons
1913
Neil’s Bohr
Tiny positive nucleus orbited by electron
Shells of fixed sizes
1926
Erwin Schrödinger
Equation where electrons had some of the wave properties and particles
Predict behaviour of subatomic particles
1932
James Chadwick and the neutron
Lewis theory
1)inertness of noble gases related to their having full outer shell
2)ions formed by atoms losing or gaining electrons for full outer shells
3)atoms bond by sharing electrons to form full outer shells
Why daltons model used
Explain geometries I’d crystals
Why bohrs model used
Ionic and covalent nsi ding
Easy to draw and understand
Number of electrons on each shell
2n^2
First shell electrons
2
Second shell electrons
8
Third shell electrons
18
Why mass spectrometer is important
Accurate determination of ram
Why carbon 12 is used
Measured on a scale on which the mass of an atom of c12 is exactly 12g
Ram equation
Average mass molecule \ 1 twelfth mass of one c12
IRL what is mass spectrometer used for
Identify substances such as illegal drugs
Wuantam mechanics and Schrödinger
Solutions to his equation gives the probability of finding an electron in a given volume of space called atomic orbital
What do orbital shapes represent
A volume of space in which there is a 95% probability of finding an electron and they influence the shapes of molecules
Energy level 1
S sub levels
1 orbitak
2 electrons
Energy level 2
S and p sub levels
8 electrons
Energy shell 3
S p d
18 electrons
Energy level 4
S p d f
32 electrons
Spun
Electrons in same orbital have opposite spins
Arrows
Time takes to detects shows
What ion
Ions accelerate to the same
Ke
Why are transition metals specifical
Chromium and copper
Donate one of their 4s electors to the 3d sun shell
More stable with a full ir half full d sub shell
Lose 4s electrons before their 3d electrons
How many orbitals in s
1
How many orbitals in p
3
How many orbitals in d
5
How many orbitals in f
7
Which transition metals are partially filled
Vanadium
Chromium
Similarity between chromium 50 and 53
24 protons and electrons
Define relative atomic mass
Weighted average mass of an atom of an element taking into account its naturally occurring isotopes relative to 1/12 the ram of an atom if carbon 12
Average mass of an atom of an element /1/12 mass of one atom of carbon 12
Now compared to rutherford
Current has neutrons and protons and orbital levels
What are energy levels divided into
Sub shells which have different energies and shape
Orbital definition.
Areas of space that predicts where an electron may be
What does the letter of orbitals show
Shape of orbital
What determines how atoms interact with each other
The arrangement of electrons
Spectra order
1)ionisation
2)acceleration
3)ion drift
4 detection
5)analysis
Now compared to Rutherford
Current has neutrons and protons and orbital levels
Rules for writing electron configuration
1)lowest energy orbital filled first aufbau principle
2)hunds rule do not pair u Tim electrons have to be paired
When in orbitals of dual energy electrons will try and remain unpaired
3)no single orbital holds more than 2 electrons
4)Pauli exclusion principle electrons have two possible states with arrows one up and one down different spin states
Electro spray ionisation
Sample dissolved in volatile substances and pushed through a small needle at high pressure
Connect to positive terminal at high voltage
Each particle gains h+ ions sample tuners into gas
Electron Impact ionisation
Sample is vapourised and high energy electrons are fired at it
Knowcks one electron off each particle so they become +1 ions
All under a high vacuum
Why vacuum used
To prevent the ions that are produced colliding with molecules from air so they don’t react inside the spectrometer
Acelleration
Positive ions attracted to negatively charged plate and accelerated towards it so they have the same KE
Lighter ions move faster than heavier ions
Ion drift
Ions pass through negatively charged plate with mi electric field. They drift
Pass through holed in negatively charged plate forming a beam and travel a to a detector
Detections
Ions with same charge arrive at detectors
Lighter ones first as they have higher velocity
Flight times recorded
Pos ions pick up electron from the detector which causes current to flow
Data analysis
Signal from the detector passed to s computer which generates a mass spectrum
Getting a mass spectrum for molecular sample
1)molecular ion - m+ formed when electron removed
2)peak in a spectrum equal to relative molecular mass of molecule
3)identify unknown compound
tof calculation steps
1) find the mass of theions times top number and divide by avagadros
2)find velocity/ke
3)find time/distance find length of tube or how long th flight takes
elrctron config
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
Ionisation energy
A measure of how easily an atom loses electrons to form positive ions
The first ionisation energy = the energy required to remove 1 electron from each atom in 1 mole of gaseous atoms of an element to form 1 mole of gaseous 1+ ions
The first ionisation energy
the energy required to remove 1 electron from each atom in 1 mole of gaseous atoms of an element to form 1 mole of gaseous 1+ ions
Endo sign
Plus
Factors affecting ionisation energy
Nuclear charge
Distance from the nucleus
Shielding
Spin pair repulsion
Type of orbital
Occupancy of orbital
Effective nucleus charge
Nucleus charge
More protons ,mor positive charge stinger attraction of electrons to nucleus
Distance from nucleus
Further away weaker attraction
Shielding
Further away more shells more shielding weaker attraction
Spin pair repulsion
When electrons are paired
There is a repulsion from each other as they have the same charge this counteracts the attraction of the nucleus they are easy to remove
High ionisation energy
A high attraction between the electron and the nucleus so more energy is needed to remove the electron
How type of orbital effects ionisation energy
Some atoms have a stable electronic configuration will resist releasing an electron so have a higher ionisation energy required to overcome the stable configuration
How occupancy of orbital affect nuclear charge
Half filled orbitals will have less tendency to release electrons therefore higher energy
How effective nucleus charge affects ionisation energy
Higher orbital is subjected to the shielding effect generated by the nergstive charged electron and doesn’t experience the full nuclear charge
What decreases ionisation
Greater period
Further away from nucleus
Lower nuclear charge
Less attraction more shielding
Easier to remove electrons
Ionisation energy decreases down the group why
-proton in atom increases nucleus charge increases
-atomic radius increases due to more shells so bugger atom
-distance beteeen electron and nucleus increases
-shielding increases due to more shells of electrons
-these factors outweigh the increased nucleus charge so it’s easier to remove the outer electron as u go down
Along the period inoinsqtion energy
Increases
Ionic bonding
Strong electrostatic forces of attraction between positive ions and negative ions
Ions are formed when one or more electrons are transferred from oNe atom to another
Why group four doesn’t forma charged ion
Form covalent bonds so no charge
Compound ions to remember
So4 2- SULFATE
OH- HYDROXIDE
NO3 -
NH4+
CO3 2-
Structure of ionic compounds
Each ion attracts oppositely charged ions in all directions
Giant ionic lattice
First electron needs the least energy
Being removed from a neutral stom
Second electron needs more energy
Because removed from +1ion
2nd ionisation equation
X=x2+ +2e-
ideal gas equation
pV=nRT
r is molar gas constant
BOYLES LAW
PV=constant
constant as long as temperature remains constant
Charles law
V/T=constant
vol of gas is proportional to the temp as long as the pressures remains the constant
gas lussac law
P/T = constant
pressure is proportional to the temp as long as volume remains constant
combining the laws give
pv/t = constant for a fixed mass of gas
r value is
8.31 j/K.mol
si units for ideal gas equation
p=pascal xkpa by 1000
v=cubic meters
t=kelvin- add 273 to degrees Celsius
r=j/k mol
why would a lighter ion be more likely to be deflected
The amount of ion drift depends upon the:
The mass of the ion - the lighter the ion the more it will be deflected.
The charge of the ion - the higher the charge the more it will be deflected.
covalent bonding
when non metals shared pair of electrons to get a full outer shell
the overlap of atomic orbitals each containing one electron to give a shared pair of electron
the shared pair of electrons are attracted to the nucleus of both the bonding atoms
graphite
each. carbon covalently binder to 3 other carbons
1 delocalised electron conducts electrons
high m+b
weak intermolecular forces
sillicon dioxide
graphene
Empirical formula
The simplest whole number ratio of moles of elements in a compound
Solid to liquid
Fusion
Energy is supplied to weaken the forces acting between particles
Latent heat of melting
Enthrall y change of melting
Enthalpy
The heat energy change measured under constant pressure whilst temperature depends on the average KE of particles and is therefore related to their speed
Greater energy -faster
Liquid to gas
Vaporisation
Energy supplied to break all intermolecular forces between particles
Energy needed =latent heat of vapourisation
Aka enthalpy change of vapourisatioin
Four types of Chrystal structures
Ionic -sodium chloride
Metallic - magnesium
Macromelular (giant covalent) - graphite and diamond
Molecular - iodine and ice
Explain why the third ionisation energy of magnesium is much higher than the
second ionisation energy of magnesium.
Electron is removed from 2p subshell
Electron being removed is less shielded
Molecular formula
The actual ratio of moles of elements in a compound
The two can be the same
