Atomic Structure Flashcards
What is the charge of proton?
e = 1.6 x 10^-19 C
What is the mass of a proton?
one atomic mass unit (amu)
What is the atomic number?
(Z) number of protons, at top of element box
What is the mass number?
A - number of protons plus neutrons
What are isotopes?
atoms that share an atomic number but have different mass numbers are isotopes of the same element, differ in the number of neutrons
What is the mass of an electron compared to a proton?
about 1/2000 of that of the proton
What are valence electrons?
electrons in the outermost shell and can participate in bonds and most easily removed, “active”
What is a positively charged atom called?
cation
What is a negatively charged atom called?
anion
What is atomic mass?
also known as mass number, is the sum of protons and neutrons
What is atomic weight?
the weighted average of these different isotopes
What is Avogadro’s number?
Na = 6.02 x 10^23
What is Planck relation?
E = hf h = Plank's constant f = frequency of radiation
What is Planck’s constant?
6.626x10-34 Js
What is the equation for angular momentum of electron orbiting a hydrogen nucleus?
L = nh/2pi n = principal quantum number h = Planck's constant
What is the equation for the energy of the electron?
E = -(Rh/n^2) Rh = Rydberg unit of energy
What is Rydberg unit of energy?
2.18x10^18 J/electron
What is ground state?
atom is the state of lowest energy, in which all electrons are in the lowest possible orbits
What is excited state?
when at least one electron has moved to a subshell of higher than normal energy
Equation for electromagnetic energy of photons?
E = hc/lambda h = plancks constant c= speed of light in vacuum lambda = wavelength of radiation
What is the value of c?
3.00 x 10^8 m/s - speed of light in a vacuum
What is the line spectrum?
each line on the emission spectrum corresponds to a specific electron transition
What is the atomic emission spectrum?
energy emitted from excited to ground state is exactly equal to the energy difference between the two levels - unique for every element
What is Lyman series?
group of hydrogen emission lines corresponding to transitions from energy levels n>= 2 to n= 1
What is the Balmer series?
group of hydrogen emission lines corresponding to transitions from energy levels n>= 3 to n=2
What is the Paschen series?
group of hydrogen emission lines corresponding to transitions from energy levels n>= 4 to n=3
What is an absorption spectrum?
exciting the electrons of a specific element results in energy absorption at specific wavelengths
Difference between Bohr’s model of the atom and the modern quantum mechanical model?
Bohr believed that electrons followed a clearly defined circular pathway or orbit at a fixed distance while the modern theory knows that electrons move rapidly and are within regions of space around the nucleus
What is an orbital?
regions of space around the nucleus
What is the Heisenberg uncertainty Principle?
It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron
What is the Pauli exclusion principle?
no two electrons in a given atom can possess the same set of four quantum numbers
What are the quantum numbers?
Principal (n)
Azimuthal/Angular momentum (l)
Magnetic Quantum Number (ml)
Spin Quantum Number (ms)
What is the principal quantum number?
n designates the principal electron shell - or the number of shells around the nucleus?
max number of e- within a shell = 2n^2
What is the angular momentum quantum number?
l - shape and number of subshells
l = n- 1
Max number of e- within a subshell = 4l+7
What is the magnetic quantum number?
ml
a particular orbital within a subshell where an e- is most likely to be found at a given moment in time
-orbitals hold max 2e-
ml = -1 to +1
What is the spin quantum number?
ms
only two spin designations - +1/2 or -1/2
Electron configuration
the pattern by which subshells are filled, as well as the number of electrons within each principal energy level and subshell
Spectroscopic notation
first number - denotes principle energy level
letter - designates the subshell
superscript - gives # of e- in the subshell
What is Aufbau principle?
electrons fill from lower-to-higher energy subshells and each subshell is completely filled before electrons begin entering the next one
What is the n+l rule?
the lower of the sum of the values of the first and second quantum numbers, n+l, the lower the energy of the subshell
What does s equal?
l = 0
What does d equal?
l =2
What does p equal?
l = 1
What does f equal?
l = 3
What is Hund’s rule?
in subshells that contain more than one orbital will fill such that there is a maximum number of half-filled orbitals with parallel spins. half-filled and fully filled orbitals have lower energies and are more stable
What are two elements with exceptions to electron configuration?
chromium and copper
Paramagnetic
Atom or substance containing unpaired electrons and is consequently attracted by a magnet.
Diamagnetic
materials consisting of atoms that have only paired electrons will be slightly repelled
