Chapter 1 Atomic Structure Flashcards
Mass Number
Sum of protons and neutrons in the atom’s nucleus
Atomic Number (Z)
Number of protons found in an atom of an element
Isotopes
Same atomic number, but different mass numbers
Different number of neutrons in nucleus
Electrostatic Force
Force between charges of electrons and protons in the element. These forces are much stronger than those of gravity.
Valence Electrons
Electrons in the outer shell that have the weakest interactions with the nucleus.
React with surrounding environment
Atomic mass unit (amu)
Protons have a mass of approximately 1 amu
1/12 the size of a carbon-12 atom
nearly equally to mass number
Cation
Positively charged atom
Anion
Negatively charged atom
Hydrogen Isotopes
Protium- 1
Deuterium-2
Tritium-3
Atomic Weight
Weighted average of the various isotopes
Avogadro’s Number
6.02 x 10^23 carbon atoms = 12 g
Ground State
Atom in the state of lowest energy
All electrons are in the lowest possible orbitals
Atoms on MCAT will most likely be in this state unless otherwise indicated
Excited State
At least one electron has moved to a sub-shell of higher than normal energy.
Line Spectrum
Each line on the emission spectrum corresponds to a specific electron transition
Atomic emission spectrum
Can be used to find which element is a certain emission
Lower to higher energy level: AHED
Absorb light, higher potential, excited, distant (from nucleus)
Series
Lyman series: n>2 to n=1
Balmer Series: n>3 to n=2
Paschen Series: n>4 to n=3
E=Rh[(1/ni^2)-(1/nf^2)]
Energy associated with a change in the principal quantum number
Emission: Positive
Absorption: Negative
The energy of the emitted photon corresponds to the difference in energy between the higher-energy initial state and the lower-energy final state
Wavelengths of absorption=wavelengths of emission
Orbitals
Where electrons are actually present
Heisenberg uncertainty principle
It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron.
Pauli exclusion principle
No two electrons in a given atom can possess the same four quantum numbers
Principal quantum number
n
Larger the principal quantum number, the higher the potential energy and the larger the radius.
Azimuthal (angular momentum) quatum number
l
=0 or (n-1)
Refers to the shape and number of subshells within a given principal energy level (shell)
Spectroscopic notation
l=0 is called s
l=1 is called p
l=2 is called d
l=3 is called f
Magnetic Quantum Number
ml
Specifies the particular orbital within a subshell where an electron is most likely to be found at a given moment in time
ml= 0 and -l to l
Spin Quantum number
ms
+1/2 or -1/2
Whenever two electrons are in the same orbital they must have opposite spins=paired
Electrons in two different orbitals with the same ms values are said to have parallel spins.
Aufbau principle (building up principle)
Each subshell will fill completely before electrons begin to enter the next one.
n+l rule
The subshell with the lower value will fill first
4l+2 rule
Number of electrons per subshell
Hund’s rule
Within a given subshell, orbitals are filled such that there are a maximum number of half-filled orbitals with parallel spins.
Paramagnetic
Magnetic field causes attraction via parallel spins
Diamagnetic
magnetic fields causes repulsion
