ATOMIC STRUCTURE
Atoms: 3 fundamental particles-protons, neutrons, electrons(in energy shells = orbitals)
Other sub-atomic particles: positron, Quak particle, J-particle

PARTICLE	REL. MASS	REL. CHARGE	SYMBOL
Electron	1/1840 (~0)	-1	0-1e
Proton	1	+1	11p or 11H+
neutron	1	0 (electrically neutral)	10n

Deflection in electric field:
-neutrons; no charge > not deflected
-protons; +ve charge > -ve plate
-electrons; -ve charge > +ve plate (v.light > deflected alot)


Deflection in magnetic field:

Deflection of some position: ²H⁺ & ⁴He²⁺

Nucleus of atom- contains (protons + neutrons) = nucleons, central mass of nucleus = nuclide (^A_ZX)
A = mass #; total # of protons + neutrons in nucleus, numerically = to RAM (molar mass = RAM expressed in g/mol)
Z = atomic #; # of protons in atom

Isotopes = same element diff # of neutrons
Carbon: 12, 13, 14 (¹⁴C formed in outer atmosphere from ¹⁴N hit by fast-moving neutrons caused by cosmic rays: ¹⁴N + ¹n > ¹⁴C + ¹H)
Hydrogen: 1, 2,3 (²H/²D: deuterium, ³H/³T: tritium)

Isotopes: stable / unstable, unstable = radioisotopes, decay naturally > new element + radiation

Uses of isotopes
Medical (radiotherapy): kill cancer cells- ⁶⁰Co (γ-rays v.strong), ³²P/⁹⁰Sr (weaker radiation > less penetrative- skin cancer)
Study of metabolic pathway: ³²P in fertilizers- how plants absorb PO₄^3-, ¹⁴C- photosynthesis (plants) & protein synthesis (animals)
Carbon-12 dating: ratio ¹⁴C: ¹²C > estimate age of wooden object; up to1000's of years only
Rock dating: ratio ²³⁸U: ²⁰⁶Pb > estimate age of Earth; (40-400) million years

Electron arrangement
Electrons- arranged in energy shells which are quantized

Principal Quantum #	Energy shell
1	K-shell (1st shell)
2	L-shell
3	M-shell
4	N-shell
5	O-shell
6	P-shell
7	Q-shell
more elements > 8	R-shell

In shells > subshells/orbits which have orbitals- regions in space (3D) where an e- most probably found

Princiapl Q#	Energy shell	Subshells
1	K	1s
2	L	2s, 2p
3	M	3s,3p,3d
4	N	4s,4p,4d,4f

Each subshell contains a number of orbitals: s = 1, p = 3, d = 5 (d_x2, d _x2_{- y}2, d_xy, d_xz, d_yz), f = 7
s-orbitals: spherical and symmetrical, p-orbitals: dumb-bell-shaped (3 sub-orbitals; p_x, p_y, p_z)

2nd Q#, l; corresponds to orbit:- l = 0:s,1:p, 2:d, 3:f
3rd Q#, m_l; max # of orbitals in orbit

Rules of Electronic configuration of atoms
-each orbital contains max 2 electron of opp spin [(anti-)clockwise]
-for degenerates (orbitals of same energy) electrons fill every orbital w/ parallel spin before pairing up
-electrons fill orbital w/ lower energy 1st before ones w/ higher energy
Ground state: electronic config w/ lowest energy level

Order of filling orbitals


Chromium: [Ar] 3d⁵4s¹ (more stable energetically)
Copper: [Ar] 3d¹⁰4s¹ (more stable)
Same electronic config = isoelectronic

In periodic table: each group has same valence shell electronic config: Group VIII = ns²np⁶
3d, 4d & 5d elements = transition elements
4f & 5f elements = inner transition elements (man-made, radioactive) (4f- lanthanides, 5f- actinides)

Ionisation energy (IE)
Conditions: 1mole, gaseous atom, isolated (no inter-atomic attraction), valence electrons in ground state
1st ionisation energy of an element = min energy absorbed to remove 1 mol of valence e- (in ground state) from 1 mol of isolated gaseous atoms of the element to form 1 mol of isolated, gaseous, singly-charged ions
M(g) - e^- >(ΔH_IE^I)> M⁺(g), ΔH= +ve

2nd IE = min energy absorbed to remove 1 mol of 2nd valence e^- (in ground state) from 1 mol of isolated, gaseous uni-positive atoms of the element to form 1 mol of isolated, gaseous, doubly-charged ions
M⁺(g) - e^- > ΔH_IE^II > M²⁺(g), ΔH= +ve
nth IE; M^(n-1)+(g) - e^- > Mⁿ⁺(g), ΔH= +ve

Factors affecting magnitude of 1st IE
positive nuclear charge attraction: from protons in nucleus, greater atomic # > more protons > valence electron more attracted > greater IE
atomic radius: larger radius > less attraction of valence electron > smaller IE

across periods IE ^ (generally- more protons & smaller atomic radii > more attraction)
exceptions:- period 2: Be & N, period 3: Mg & P -due to extra stability w/ filled s config- Group II and ½ filled p config- Group V > more energy absorbed to remove e^- [(½) filled orbitals > more stable]

down groups IE decreases: atomic radius ^ due to e^- screening- repulsion bet e^-s in shell > valence e-s far from nucleus > nuclear charge attraction decreases

transition metals:across periodic table- IE very little fluctuation

graph of lgIE vs # of e^-s remove shows difference in successive IE's (pts before large gap= # of e^-s in valence shell)


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