chem Flashcards
(41 cards)
which s-block metal has the highest first ionisation energy
Be (Beryllium) as it has the lowest shielding but the most protons
what’s the general trend in ionisation energy as you go across a period
it increases
does (B) boron or (Be) beryllium have a higher first IE, explain why
Be: 1s2 2s2
B: 1s2 2s2 2p1
it’s easier to remove a single e- from a p sub shell to make it have perfectly filled sub shells compared to removing an e- from already perfectly filled sub shells
what is the formula for kinetic energy and what units
KE= 1/2 x mass(kg) x (velocity)2 (m/s)2
what formula relates distance velocity and time
time= distance
velocity
what’s the relative mess of an electron
1
1840
what model did jj Thomson come up with in 1904 for the structure of an atom
he came up with the plum pudding model that stated atoms there a positive ball with negative electrons through out ( like radians in a plum pudding)
what evidence was found to support Rutherfords nuclear model of the atom?
Rutherford fired He2+ ions at. a sheet of gold foil when the he2+ ions where able to mainly pass through the gold sheet with only a some being slightly deflected and even fewer being fully bounced back he concluded that atoms where mainly empty space but had a tiny positive nucleus.
what’s the definition of ionisation energy
the amount of energy needed to remove one mole of electrons from one mole of atoms in the gaseous state
what are the 3 factors that effect ionisation energy
nuclear charge
distance from the nucleus
shielding
why is Li a bigger atom than F
they have the same amount of shielding but F has more protons meaning there ave more attraction with the shells causing the she’s to be pulled closer to the nucleus
what’s the tend in ionisation energy as you go across a period
it generally increases with a few exceptions
how does a TOF mass spectrometer work ( 6 parts)
1) VACCUM the entire machine is a vacuum to prevent any of the particles being tested colliding with molecules from the air
2)IONISATION two methods of ionisation:
a) electron impact (electrons fired at particals)
b) electro spray (H+ ions (protons)) are fired at the particles
3) ACCELERATION the positive ions are attracted to a negatively charged plate and accelerate towards it. high m/z ration ions will accelerate to lower speeds than low m/z ratio ions. (when accelerated all ions will have the same kinetic energy.
4) ION DRIFT some ions will pass through the hole in the negatively charged plate and travel along the flight tube towards the detector, as particles are traveling at different speeds they drift further apart as the slower particles cart keep up.
5) DETECTION different m/z ions arise at detector at different times due to their different velocity the “time of flight” is recorded and as each ion hits the detector it gains an electron. this generates a current the size of which is proportional to the number of each type of ion
6 data análisis- the signal from detector then is passed through the computer which generates a mass s[ectrem.
how are the ions detected in a time of flight mass spectrometer
each ion hits the detector
ion gains an electron
generates a cutest
size of current is proportional to the abundance of the ion
what’s the formula for calculating Ar
sum of all abundances
What is produced when sulphuric acid reacts with sodium fluoride?
(You may select more than one)
H2S
HF
S
F2
SO2
HF
Balance the following half equations
Fe2+ -> Fe3+
MnO4- -> mn2+
Combine them
Fe2+-> e- + Fe2+
MnO4- + 8H+ -> 4H2O + 2e- + Mn2+
what is the product of H2SO4 and Br- and
SO2 (sulfer dioxide) / acidic chocking gas
what 3 products can be formed in the reaction of H2SO and I- and describe them
SO2 (acidic choking gas)
S yellow solid
H2S bad egg smell
write the half equation for 2I- —> I2 and what appears
2I- —-> I2 + 2e- black solid formed
balance the following half equation Br- —-> Br2 and what the product is and looks like
2Br- —-> Br2 + 2e
brown fumes
whats the trend of the reducing strength of halides as you go down the group
it increases as ions radius increases and so weaker attraction between outer e- and nucleus.
this id the model proposed by Rutherford. state two features not shown in the Rutherford model
1: positive protons and neutral neutrons in the positive nucleus.
2: sub shells that hold the electrons
