ATOMIC STRUCTURE/AOS Flashcards by Hajra Azeem

What was Niels Bohr’s model & discovery?

Model: where electrons exist in shells or orbits of fixed energy
Discovered: When electrons move between shells, electromagnetic radiation (with fixed energy or frequency) is emitted/absorbed

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protons charge and mass

mass: 1
charge: +1

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Neutrons charge and mass

mass: 1
Charge: 0

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Electrons charge and mass

charge: -1
Mass: 1/1840

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Iosotopes

same No of protons
Different No of neutrons
same e- configuration

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1st ionisation energy

ENTHALPY CHANGE WHEN ONE MOLE OF e- IS REMOVED FROM ONE MOLE OF GASEOUS ATOMS TO FORM ONE MOLE OF GASEOUS 1+ IONS

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trend in ionisation energy along a period?

ionisation energy increases

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why does ionisation energy increases along a period?

atomic radius decreases
increases in charge
outer e- is strongly attracted to nucleus so requires so more energy required to remove outer e-

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trend in ionisation energy down a period?

ionisation energy decreases

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why does ionisation energy decreases down a period?

attraction between nucleus and outer e- decreases
more shielding
less energy required to remove outer e-

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Trend in ionisation energy across P2? (6 marker)

STAGE 1
General increase in IE
same shielding as same number of shells
greater attraction between nucleus and outer e-
STAGE 2
B lower than Be
outer e- in 2P
higher in energy than 2S
STAGE 3
O lower than N
2 e- in 2P needed to be pair
e- pair repulsion

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Define Ar

Mean mass of an atom of an element /one twelfth of the mean mass of an atom of the carbon 12

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Define Mr

mean mass of a molecule of a compound/ 1 twelfth of the mean mass of ab atom of the carbon 12

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Calculate:
No of particles

moles x 6.022x10^23

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calculate moles
(2 equations)

Mass/ Mr

Con x Vol

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percentage yield

experimental mass 100 / theoretical mass

atom economy

Mr of desired product 100/ Mr of reactants

empirical formula steps

simplest whole number ratio
1. mass/ %
2. / Ar
3. / smallest value
4. ratio

steps to make up a standard solution (6marks)

weigh sample containing solid on a balance
transfer to beaker and reweigh sample bottle
record difference in mass
add distilled water
still until solid dissolve
transfer to volumetric flask using a funnel
7 with washing
8 make up to 250cm3
9 mix

Bohe model 3 mark points

Protons and neutrons are found in the center of the atom called nucleous
Protons and neutrons can also be called nucleons
Electrons saurround the nucleous in shells

What in atomic number (Z)

Number of protons

What is mass number (A)

Protons + neutrons

What is cations and anions

Cations- lost electrons ( +ve charge)
Anions- gained electrons ( -ve charge)

Write the first and second ionisation evergy for X

1st: X(g) ——> X+(g) + e-
2nd: X+(g) ——> X2+(g) + e-

What 3 factors influence ionisation energy

Nuclear charge Shielding Distance from nucleus

Electron impact

sample vaporaised High electrons are fired at samo,e by electron gun Ehich knicks off one electron

Equation of electron impact

X(g) ——> X+(g) +e-

Electrospray ionisation

Sample dissolved in a volatile solvent and injected through a hypodermic needle which is attached to the positive terminal of a high-volatge power supply Particles ionised by gaining a proton

Equation of electrospray ionisation

X(g) + H+ ——> XH+(g)

Why are sample particles ionised in mass spectometry

Can be accelerated towards negatively charged plate So they generate a current then they hit the detector

How is the ion accelerated in mass spectometry

+ve ions attracted to negatively charged plate All ions have same Ke

How are ions separated in the flight tube?

Ions travelling at higher soeeds (small m/z) move ahead of those travelling more slowly

How are ions detected

Each ions hit detector Ions gains an electron Generates a current Size of current is proportional to the abundance of the ion

Why is mass spectometry in a vacuum

No Particles being tested colliding with molecules from the air

How are ions detected and how is there ambumcane sample

Positive ions ganis electron when they arrive to the detector Generates a current which is proportional to the number of each type of ion