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GENERAL CHEMISTRY NOTES
- the first toackowledge atoms was Democritus (but more in a philosophical way).
- John Dalton was the first to provide solid evidence that atom exist. -(due to a diffrence b/t democritus' theory and dalton's evidence) JJ Thomson showed that atoms must contain ofsmaller particles(negative and positive charged particles) but he didn't know how they were distributed.
- Ernest Rutherford took it further just a bit later.
-atomic number = nb of protons. -mass number(nb of particles) = protons + neutrons. (^4) He == Helium-
-diff # of p = diff elements. in the periodic table the elements are arranged by atomic nb. -diff # of n = diff isotopes. -diff # of electrons = diff ions.
Matter is anything that hasmass andoccupy space. Phases of matter: Solid(fixed shape/volume), Liquid(fixed volume =! shape) and Gas(=! volume/shape). Physical change: substance changing from onephase to another. Chemical change: chemical compositiondoes change creating new substances.
Rules for significant figures:
non-zero digits are significant. zeros b/t other digits are significant. > whatever the answer u'll have toround up ordown at the appropriate digit.
leading zeros are not significant.
trailing decimal zeros are significant.
adding/substracting: fewest nb of decimal places.
multiplying/dividing: fewest nb of sig figs.
History of atomic theory:
Nuclide symbols:
e.g:
- nb of particles in one mole of a substance. -conversion b/t moles and grams depend on it. (nb of moles = nb of particles/NA)
-to find the molar mass of a substance add atomic masses of all the atoms in it. e.g:
- won't automatically be the substance that is present in the lesser amount.
Avogadro's number: NA = 6.02214076x10²³
Molar mass: M = m(mass)/n(moles)(g/mol)
Limiting reagent: the one thatruns out first and makes reacting further impossible.
(1) we need to know the molecular mass of the molecule we're searching for. (2) find how much one unit of the empirical formula weighs. (1)/(2) = a => CaX HaY
e.g:
(P) = the force the gas[particles] is exerting on the container. (T) = the amount of heat energy available to be transferred into kinetic energy of motion. the higher T the fastest the particles move. (V) = volume of the container. (n) = how many particles are in the container.
0 K = -273° C / K = C + 273 / C = K + 273
-Boyle's law: P 1 V 1 = P 2 V 2
-Charles's law: V 1 /T 1 = V 2 /T 2
-Combined Gas Law: (P 1 V 1 )/T 1 = (P 2 V 2 )/T 2
-Avogadro's Law: V 1 /n 1 = V 2 /n 2
-Ideal Gas Law: PV = nRT (R = 0.0821)
- wavelength λ = distance from tip to tip (nm).
- frequency υ = number of waves that pass by a point per unit time (Hertz = 1/s). (λ and υ are inversely proportional)
- amplitude A = max. and min. distance in positive and negative directions (m).
Molecular formula: (the actual number of atoms of each element in a molecule).
Ideal Gas:
- Particles are points in random motion.
- Particles don't interact.
Electromagnetic Radiation: c = λ. υ
- photon = particle of light.
light obeys wave-particle duality (it is both a particle and a wave at the same time).
(higher/low frequency = higher/not enough energy photons).
e.V = e's energy. mu² = kinectic energy gained by e. h.v = photon's energy.
-an electron can only inhabbit certain energy levels that are at fixed distances from the nucleus, each type of atom has its energy levels at diff values (cz of diff # of p and e). -for an e to transition between energy levels : either absorb or emit a specific amount of energy. -----> change in the energy level: Δ Eelectron = Ephoton
-for a hydrogen atom:
-----> Eelectron = -RH/n² (RH = 2.179 x 10-18^ J)
-----> change in the energy level:
e.g:
Atomic Line Spektrums : (IT'S CUTE) https://youtu.be/oae5fa-f0S Quantum Theory: everything is quantized, space and time too (so they can't be infintely subdivide).
- interaction b/t light and matter: E = m.c^
- energy of photon/ at each energy level: E = h. υ [E = hc/ λ ] (h = 6,62607 x 10-³² J s)
Photoelectric Effect = when light strikes to a surface of metals, electrons are ejected.
Bohr Model :
n (energy level)= can have any positive integer value / it represents the energy of the electron / each orbital will have an n value / the larger the value the further away from the necleus it is.
l (angular momentum quantum number) = ∈[0, n-1] / discribes the shape of the orbital 0 → s(1 per energy level) 1 → p (3 per e.l) 2 → d(5 per e.l) 3 → f (7 per e.l).
ml (magnetic quantum nb) = equals to {-l.....l}.
ms (spin quantum nb) = equals to +1/2 or -1/2.
these shapes are regions in space where electrons can be, and each hold up to two electrons.
T.N: two electrons in an atom can't have precisely the same four quantum nbs cz any orbital can only hold up to two electronsand even these 2 e in the same exact orbital will have opposite spin values.
Quantum numbers : 4 sets that determine the location and energy of electrons, that describe diff atomic orbitals.
Orbital : a region of probability were an electron can be found. [s, d, p and f]
-orbitals that are further away from the nucleus have higher potential energy.
Aufbau Principle : tells us the order in which an atom will fill up its orbitals, this is determined by their relative energies.
Electron Configuration:
Electron Configuration from periodic table : Left to right and up to down:
Adding/taking an e makes the atom bigger/smaller.
The farther away an electron is from the nucleus the easier it is to pull it away. Ionization energy increases up and right. -second ionization energy will always be greater than the previous one.
electron affinty increases up and right.
electronegativity increases up and right. T.N: Noble gass are disregarded for both electron affinity and electronrgativity.
Ionic Radius : distance b/t the nucleus and the outermost shell.
Ionization Energy : energy required to remove an electron from the atom(i the outermost shell).
Electon Affinity : how much an atom wants to gain an electron.
Electronegativity : the ability of an atom to hold electrons tightly.
