CHM1011 Flashcards
(23 cards)
ionic bond
the electrostatic attraction between a cation (positively charged atom) and an anion (negatively charged atom).
metal + non-metal
naming salts (ionic)
- Cation: name as the element/compound.
e.g. Mg2+is magnesium, NH4+is ammonium
- Anion: if there is just one element, end with “-ide”
e.g. Cl-is chloride, S2-is sulfide
Anion: if there is oxygen in the anion, end with “-ite” or “-ate”
e.g. NO2-is nitrite, SO32-is sulfite, PO33-is phosphite.CO32-is carbonate, NO3-is nitrate, SO42-is sulfate, PO43-is phosphate.
covalent bond
Covalent bonds are where atoms share their electrons to fill their outer shell. (Non metals)
Groups of atoms that share electrons covalently with each other are called molecules
naming covalent compounds
first element = prefix + element name
second element = prefix + stem + suffix (-ide)
mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
electronegativity
- The ability of an atom to attract electrons towards it - when it’s part of a molecule
- Electronegativity can be used to determine the “covalency” or “ionicity” of bonds
VSEPR theory
model used to predict the shape of molecules
Each group of valence electrons around a central atom is located as far away from the others as possible in order to minimise repulsions
The relationship relating frequency and wavelength
Radiation can be measured as:
νλ=c
frequency: symbol-νand units - Hz, or s -1
wavelength: symbol-λand units- metres
velocity = speed of light (c), and is 2.998×108m s-
amplitude
intensity of the radiation
the measure of the strength pf the light - e.g. the power on laser beams
wavelength
λ - distance between corresponding points on adjacent waves
frequency
(ν) = number of waves passing a given point per unit of time
for waves traveling at the same velocity, the longer the wavelength, the smaller the frequency
solve for frequency
ν = c / λ
Planck’s constant
6.63×10−34 joule-hertz−1
planck’s equation
helps us calculate the energy of photons when their frequency is known
E = hc / λ
E - energy
h - planck’s constant
c - speed of light
λ - wavelength
quanta
the plural of quantum = minimum amount certain properties of a system can change.
In relation to light, the quanta are known as photons, a particle-like interpretation of light waves
relationship between energy and frequency
E = hv
schrodingers equation
HΨ = EΨ
Ψ is the 3-dimensional coordinates, E is the total energy and H is the kinetic and potential energy
- electrons are both waves and particles
- probability of finding an electron at a point of space from the nucleus
quantum numbers
represent the unique solutions to the Schrödinger equation, describe energy levels
Quantum model explains that electrons are smeared out according to energy levels, which helps determine an element’s spot in the table
n, l, ml, ms
principal quantum number (n)
defines the location of the energy level. It can take integral values such as 1,2,3,4, etc. The larger the value of n, the farther is the energy level from the nucleus.
angular momentum quantum number (l)
specifies the shape of the orbital.
Its value ranges 0 to n- 1. An orbital with n=1 has an l value of 0, while an orbital with n=2 can take l values of 0 and 1.
- l = 0, orbital = s
- l = 1, orbital = p
- l = 2, orbital = d
- l = 3, orbital = f
e.g when n=3 and l = 2
It’s a 3d orbital
magnetic quantum number (ml)
indicates the orientation of an atomic orbital around the nucleus. It may take integral values from -l to +l, hence, the total number of possible orbitals with a value of 1 is 2l + 1.
For instance, there is only one possible orientation for an s orbital because its l value is 0 and 2l + 1 = 1. On the other hand, a p orbital (with l=1) can have 3 possible orientations [2(1) + 1 = 3].
spin quantum number (ms)
specifies the direction of the spin of an electron located in an orbital.
It can have a value of either+1/2 or -1/2. This quantum number therefore indicates that there are only two possible directions for an electron spin i.e. opposite of one another, and that each orbital can be occupied by a maximum of two electrons
probability density
describes the probability of finding an electron at a point in space (from Ψ^2) with respect to the distance, r, from the nucleus
rises as it gets closer to the nucleus, acetetoting towards 0 as it goes further away from the nucleus but never gets to 0, always a probability of finding the electron
radial density function
probability of finding an electron (from Ψ^2), within a spherical shell (distance r from the nucleus)
since the volume of these shells increases as r increases, the function increases from zero through a maximum before tending to zero again
