Midterm 1 Flashcards
What is electromagnetic radiation?
It exhibits wavelike properties of electric and magnetic fields, and all electromagnetic radiation travels at the same velocity.
Characteristics of waves
Wavelength, frequency, and amplitude
Amplitude
Intensity, height of the wave maximum from centre
Wavelength
Number of waves passing a given point per unit of time
Blackbody radiation
Hot objects emit light and the wavelength depends on the temperature of the substance and based on quanta.
Quanta
Energy can only be absorbed/released in certain amounts
Not explained by classic theory
Blackbody radiation, photoelectric effect, line spectra
Quantum
The smallest amount of energy that can be emitted/absorbed as electromagnetic radiation
Photoelectric Effect
The emission of electrons from a metal when light shines on the metal that increases with brightness and frequency of incoming light
Line Spectra
The emission of light only a specific wavelength. Proves the existence of quantized energy
Line Spectrum
Line spectra emitted from excited gaseous elements, when separated by a prism splits light into component wavelengths
Continuous Spectrum
When radiation from a light source is separated into its different wavelength components but it is not true for excited gaseous elements.
Ground State
Lowest energy state
Quantized Energy
Electrons can only posses certain energy values; values between are not permitted. Electrons move to lower energy as light is emitted in the form of wavelength and move to higher energy states as light is absorbed.
Emission Lines
Caused from excited electrons dropping into lower energy orbitals, colours depend on the energy change during emission.
Uncertainty Principle
Cannot determine exact position, direction of motion or speed of particles simultaneously because the measuring process interferes with what is being measured.
Principle Quantum Number
n, describes main energy level and specifies electron shell
Angular Quantum Number
l, describes shape based on subshell (s, p, d, f)
Magnetic Quantum Number
ml, designates a specific orbitals and specifies orientation, based on order of electron being placed in orbitals. Each electron can only have one magnetic quantum number. -l…0…+l
Spin Magnetic Quantum Number
ms, describes the spin of the electron and based on the order of electrons placed in orbitals. = +/- 1/2
Node
Region where the probability of finding an electron is zero. The number of nodes is given by n-1
S-Orbitals
Spherical shaped and starts from 1s. Only have radial nodes and can hold up to 2 electrons. (1 set of 2) n-l-1 radial node(s), n phases
P-Orbitals
Dumbbell shaped and starts from 2p. Can hold up to 6 electrons. (3 sets of 2) n=l angular nodes and n-l-1 radial nodes
D-Orbitals
Four-leaf clover shaped, starts from 3d. Can hold up to ten electrons. (5 sets of 2) n=l angular nodes and n-l-1 radial nodes
F-Orbitals
Starts from 4f. Can hold up to 14 electrons. (7 sets of 2) n=l angular nodes and n-l-1 radial nodes
Pauli’s Exclusion Principle
No 2 electrons can have the same set of 4 quantum numbers and electrons in the same orbitals must have opposite spins.
Degenerate Orbitals
Orbitals with the same energy. The lowest energy is attained when the number of electrons with the same spin are maximized.
Electron Configuration Exceptions
A more stable configuration of electrons is when a set of p and d orbitals are either filled or half-filled, so Cr, Cu, Mo, Pd, Ag, Gd, Th, Pa, U, Np, Cm, Bk
Atomic Size
Increases down and to the left of the periodic table. Nuclear charge increases as atoms get smaller.
Effective Nuclear Charge (Zeff)
Charge experienced by an electron on a many-electron atom. The electron is attracted to the nucleus, but repelled by electrons that shield or screen it from the full nuclear charge. Higher Zeff means more charge and stronger bonds. Increases to the right of the periodic table and slightly down. Calculated by Zeff = Z-S, where Z is the atomic number and S is called the screening/shielding constant, represents the portion of the nuclear charge that is screened from the valence electron by other electrons in the atom. Also the number of core electrons based on the electron(s) being calculated.