2 atomic structure Flashcards by rui en

structure of an atom

positively charged nucleus
‘cloud’ of negative charge

electrostatic attraction betw pos nucleus and neg charged electrons – holds it tgt

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define isotope

different atoms of the same element
same protons
but diff number of neutrons

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speed of light? (in section 2 of data booklet)

3.00 x 10^8 m/s

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excited state electrons are further / closer to the nucleus

further (higher energy level)

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in a line emission spectrum of hydrogen, describe the lines

they get closer toegther towards the blue end of the spectrum (convergence towards the higher energy end)

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what does it mean when lines converge towards the higher energy end in an emission spectrum

the electron is reaching its maximum amt of energy = ionisation energy of the electron

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who observed line emission spectra

Johannes Balmer

(the balmer series is in the visible spectrum)

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lines in an emission spectrum correspond w the electron jumping from _____ levels to the ______ energy level

higher

second

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when an electron jumps to n3, what is the region and energy level?

infrared

low

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when an electron jumps to n2, what is the region

visible

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when an electron jumps to n1, what is the region and energy

ultraviolet

high

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how to calculate the number of electrons each principal quantum number can hold?

2n^2

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how many electrons can the principal quantum number 3 and 4 hold?

well yknow n=1 can have 2 and n=2 can have 8 BUT as it turns out
3 = 18
4 = 32

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what is the sequence of letters for the subshells! + how many electrons can each have

s p d
2 6 10

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s and p orbital shapes

s is just a sphere around the centre

p is a dumbell shape? along the axes so like an hourglass

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what is the ground state of an atom

most stable electronic configuration with lowest amount of energy

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what is the Aufbau principle

ground state is acheived by filling subshells with lowest energy first
(does not follow pattern above n=2)

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exception to subshell increase in energy as follows: s < p < d < f

3d subshell has slightly higher energy level than 4s = 4s filled first

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what does it mean when orbitals are ‘degenerate’?

orbitals in the SAME subshell have the same ENERGY (1s=2s=3s=4s)

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subshells can be further divided into orbitals, which each can hold ___ electrons

so if theyre like ooh 2p subshell how many orbitals?? well it can hold 6 electrons so 3 orbitals

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the size of s orbitals increases with _______ shell number

increasing

so like n=3 is gonna be a bigger sphere than n=1

p subshell has ____ orbitals and they are oriented?

3 orbitals

occupy x,y,z axes perpendicular to each other in a dumbell shape

shape change of p orbitals with increasing principal quantum number?

longer and larger lobes

what is spin-pair repulsion?

when 2 electrons spinning in the same direction (same spin) repel each other

what is Hunds rule?

due to spin-pair repulsion, electrons occupy seperate orbitals before pairing up with another with opposite spin (basically in the square thing, you fill in ^ ^ ^ before going ^v ^v ^v)

what is the Pauli Exclusion principle?

an orbital can hold 2 electrons and they must have opposite spin

how does shorthand electron configuration work

use the nearest preceding noble gas + rest of the config [Ar]3d^54s^1

transition metals fill the 4s/3d subshell first and lose electrons from the 4s/3d subshell first

4s !!!

according to electronic configuration, how is the periodic table split up?

left grp: s block mid (transmetals): d block right (nm): p block below: f block

name the 2 exceptions to Aufbau principle

Cr (Chromium) Cu (copper)

Cr is NOT 3d4 4s2 it is?

3d5 4s1

why are Cr and Cu exceptions to Aufbau principle

its more energetically favourable to have a full/half 3D SUBSHELL than a full 4s

when energy is released when electron goes from n=2 to n=1, what series does it correpsond with?

ultraviolet Lyman series

what is Bohr's model?

idea that electrons exist in discrete energy levels SO an EXACT amt of energy is needed to 'jump' an energy level

3 limitations of Bohr's model

1. assumes positions of electrons are FIXED 2. assumes energy levels are SPHERICAL in nature 3. only applicable to HYDROGEN

what is the limit of convergence?

the frequency at which the spectral lines appear to meet // converge = first ionisation energy

frequency of radiation in emission spectrum at the limit of convergence can be used to determine the ?

first ionisation energy

what is the first ionisation energy from the Lyman series?

UV region! limit of convergence = energy given out when electron falls from n=infinite to n=1

what data booklet constant will you need to calculate first ionisation energy using convergence limit?

plancks constant!

in the conversion between wavelength and frequency whats the unit for wavelength

m! so if its nm then you gotta x10^-9

convert J to kJ

divide by 1000

2 things to rmb when calucating first ionisation energy from convergence limit

convert to per mole using AVOGARDOS CONSTANT convert final units to kJ/mol (if asked for) - all eqns in formula booklet

4 factors affecting first ionisation energy

1. size of nuclear charge 2. distance of outer electrons from nucleus 3. shielding effect (inner electrons) 4. spin pair repulsion

first ionisation energy ______ across a period and _______ decreases down a group

increases decreases (top right corner highest)

explain the increase in ionisation energy across a period 4

nuclear charge incr atomic radius decr = decr dist shielding constant harder to move electron = more energy needed

dips in the trend of first ionisation energy increasing across the period name 2

between beryllium and boron between nitrogen and oxygen (spin-pair repulsion)

why is there a dip in the ioniastion energy trend between beryllium and boron

distance 5th beryllium electron is in 2s BUT 5th in boron is in 2p (further) = lower

why is there a dip in the ioniastion energy trend between nitrogen and oxygen

spin-pair repulsion in 2p orbital of oxygen nitrogen has p orbital ^ ^ ^ oxygen has p orbital ^v ^ ^ = repulsion = easier to remove = decr first ionisation energy

how does first ionisation energy change one period to the next + why? (dist, shielding, charge)

it has a LARGE DECREASE - incr dist - incr shielding bc new shell - outweighing the incr nuclear charge

why do successive ionisation energies increase

remove first electron = ion more difficult to remove electron attractive forces incr with electron decr - decr shielding - incr charge also depends on electronic configuration

big jumps in successive ionisation energies = ?

change of shell (so if 2nd is hard to remove, there is 1 valence electrion) (smaller jumps = change of subshell)