NYA Equations 
STOICHIOMETRY 
number of mole (n) 

number of particle = mole x Avogadro number (mol^{1})  number particle = n x N_{A}
(N_{A} = 6.022x10^{23} mol^{1})

mass% 
mass%(A) = 100% x 
mass of A in the sample 
total mass of the sample 

GASES 
Ideal gas law  P V = n R T 
TYPES OF CHEMICAL REACTIONS and Solution Stoichiometry 
molarity (M in mol.L^{1}) 
M = 
n_{solute} 
V_{solution} 

att: FOR DILUTION ONLY (the number of mole is constant)  c_{1}V_{1} = c_{2}V_{2} 
ATOMIC STRUCTURE AND PERIODICITY 
Relation between the speed of light c, the wavelength λ and the frequency ν  c = λ ν 
The quantum of energy absorbed or emitted by an atom (h = Planck constant)  ΔE_{atom} = h ν
ΔE can either be positive or negative

Energy of a photon  E_{photon} = h ν
ΔE_{photon} > 0 (always)

The photoelectric effect (Einstein) 
E_{kinetic} = ½ m_{e}v^{2} = h ν  h ν_{o}

m_{e}: mass of the electron, v: speed of the electron,
ν_{o}: threshold frequency to extract the electron from the surface.


de Broglie wavelength (wavelength of a moving particle) 

m: mass, v: speed of the moving particle


The Bohr model of an atom 
E_{atom} = (−2.178×10^{−18} J) 
Z ^{2} 
n ^{2} 

Z atomic number (number of protons)
n main quantum number (energy level)


Change of energy of an atom  ΔE _{atom} = E _{final} − E _{initial} 
Heisenberg uncertainty principle


Δx: uncertainty on the position,
Δ(m v): uncertainty on the impulsion (mass × speed) 

BONDING GENERAL CONCEPTS 
Coulomb's law: Energy of interaction between a pair of ions 
E = (2.31x10^{−19 }J·nm) 
Q_{1}Q_{2} 
r 

(no need to memorize this equation, just understand.)


Bond energy and enthalpy  ΔH _{reaction} = Σ_{n}D_{bonds broken} − Σ_{n}D_{bonds formed} 
Lewis formal charge (FC ) calculation 
FC = n_{valence electron in the free atom } − n_{electron in lone pair } − 
n_{electron shared} 
2 

COVALENT BONDING 
Bond order (BO ) calculation 
BO =
 n_{ bonding electron} − n_{ antibonding electrons} 
2 

THERMOCHEMISTRY 
Enthalpy 'H' of a reaction  ΔH _{reaction} = ΣΔH _{products} − ΣΔH _{reactants} 
Specific Heat capacity c 
c =
 heat absorbed 
ΔT x mass (g) 
where:
ΔT = T_{final} − T_{initial}

Heat q transfered by a reaction 
q = m × c × ΔT 
Conservation of the energy 
q_{system} + q_{surrounding} = 0 
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