Chapter 1 Flashcards
Protons
- found in nucleus
- charge = 1.6*10^-19 OR +1
- Mass of 1 amu (atomic mass unit)
- Elements are defined by their # of protons
The atomic number (Z) is equal to
the number of protons found in an atom of that element
Neutrons
- Have no charge
- Found in nucleus with protons
Mass number
Sum of protons and neutrons in nucleus
Isotopes
- Share atomic # but different mass #s
- Only differ in number of neutrons, same amount of protons
Electrons
- Found in orbitals around nucleus
- Charge of -1
- Electrons closer to nucleus have lower energy
- Electrons farther from nucleus (higher shells) have more energy
Valence electrons
Electrons farthest from nucleus that have strongest interaction with surroundings and weakest interactions with nucleus
* Most likely to bond with other atoms due to weak pull from own nucleus
* Determine reactivity
Losing electrons yields
positive charge
Gaining electrons yields
negative charge
Positively chargted atom
Cation
Negatively charged atom
Anion
Atomic Mass
Nearly equal to mass number (sum of protons and neutrons)
Think mass … mass number
Atomic Weight
- Weighted average of all the different isotopes making up an element
- Number found on the periodic table
Think weight … weighted average
Mole
- Can be atoms, ions, molecules, etc.
- =6.02*10^23
Planck Relation
Planck’s constant
h=6.626*10^-34
Angular Momentum
h = Planck’s constant
n = principal quantum number
Energy of an electron
- Changes in discrete amounts with respect to the quantum number
- Energy of an electron increases (become less negative) the farther it is from the nucleus
R_H is the Rydberg unit of energy
Ground State
- State of lowest energy
- All electrons are in lowest possible obirtals
- Desire this minimal energy state
Excited State
- Electron is promoted to an orbit with a larger radius (higher energy)
- At least one electron has moved to a subshell with higher than normal energy
- Will occur due to extremely high temperatures or irradation
Electron movement from low to high energy
AHED
A Absorb light
H Higher potential
E Excited
D Distant (from nucleus)
Electromagnetic Energy of photons
Line spectrum
Emission spectrum with each line corresponding to a specific electron transition
Energy of emitted photon corresponds to difference in energy between the initial state (higher energy) and the final state (lower energy)
+E = emission
-E = absorption
To gain energy, must absorb energy from photons too jump up to higher energy level
Maximum number of electrons within a shell
2n^2
Principal Quantum Number (n)
- The larger the value of n, the higher the energy level and radius of the electron’s shell
- Difference in energy between two shells descreases as distance from nucleus increases
Azimuthal (Angular Momentum) Quantum Number (l)
- Shape and number of subshells within a given principal energy level (shell)
- l = 0 to (n-1)
Subshells
l=0 (s)
l=1 (p)
l=2 (d)
l=3 (f)
Maximum number of electrons within a subshell
4l+2
Magnetic quantum number (m_l)
- Specifies the orbital within a subshell where an electron will be most likely found at a certain time
- Each orbital can hold max 2 electrons
- Possible values: - l, 0, +l
Orbital Shapes
Subshell Amounts
S: 1 (2 elements)
P: 3 (6 elements)
D: 5 (10 elements)
F: 7 (14 elements)
Spin quantum number (m_s)
- When two electrons are in the same orbital, they must have opposite spins (AKA being paired)
- Electrons in different orbitals with the same m_s have parallel spins
____ will fill first
Subshells with lower energy
n + l Rule
Lower n+l value has lower energy, therefore filling first
Electron Configuration
Electron Configuration of Ions
Will remove from subshell with higher principal quantum number first, then go down
Half-filled and fully filled orbitals have …
lower energy and higher stability
TWO Electron Configuratoin Exceptions
Chromium: [Ar]4s^1 3d^5
* Half fills 3d subshell making a lot more stable
Copper: [Ar] 4s^1 3d^10
* Fully fills 3d subshell making a lot more stable
Other elements in this group exhibit the same behavior
Similar shifts seen in f subshell but NEVER p subshell
Paramagnetic
Materials made of atoms with unpaired electrons will orient their spins with the magnetic field, thus the material will be weakly attracted to the magnetic field
Diamagnetic
Materials made of atoms with paried electrons, thus the material will be slightly repelled by a magnetic field
Heisenberg Uncertainty Principle
It is impossible to determine at the same time with perfect accuracy the momentum and position of an electron
Hund’s Rule
Orbitals are filled so there are a maximum number of half-filled orbitals with parallel spins
Parallel
Electrons in different orbitals with the same m_s
Speed of light in a vacuum (C)
3*10^8
