Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
71 Cards in this Set
- Front
- Back
Diatomic Elements
|
Hydrogen (H2)
Nitrogen (N2) Oxygen (O2) Fluorine (F2) Chlorine (Cl2) Iodine (I2) Bromine (Br2) |
|
Explaining Diatomic Bonding
|
-These seven elements (H, N, O, F, Cl, Br, and I) are called the diatomic elements because, as pure elements, they form molecules containing two atoms
-no additional bonding is needed. -covalent bonding between atoms of the same element |
|
Bohr Model and Quantum-Mechanical Model
|
-explain inertness, reactivity and the perodica law of elements
-explain how electrons exist in atoms and how those electrons affect the chemical and physical properties of elements |
|
What is Light?
|
-Light is electromgnetic radiation
-A type of energy that travels through space at a constant speed -light is not matter |
|
What is the speed of light?
|
3.0 x 10^8 m/s (186,000 mi/s)
|
|
Speed of Light vs Speed of Sound
|
Light travels faster hence fireworks ... explosions are heard after light appears
|
|
Wavelength
|
- the distance betwen adjacent wave crests
-Lambda -determines color of visble light |
|
Frequencies and Wavelengths
|
Higher frequencies have shorter wavelengths, and lower frequencies have longer wavelengths.
|
|
Longest - Shortest Wavelengths
|
Red
Orange Yellow Green Blue Indigo Violet |
|
Red vs Violet
|
Red has longest wavelengths in visble light
Violet has the shortest wavelength in visible light Red = 750nm Violet = 400nm |
|
Why is a red shirt red?
|
-the shirt reflects red light
-shirt absorbs all other color except red |
|
Frequency
|
-number of cycles of crests that pass through a stationary point in one second
|
|
Wavelengths and Frequency
|
-Inversely related
-shorter the wave length the higher the frquency |
|
Redefining Light
|
-Einstien described light as particles
|
|
Photon
|
-a particle of light
-a single packet of light energy -amount of energy carried by packet depends on the wavelength of the light |
|
Energy in Photon
|
Depending on the wavelength of the light increases of decreases the amount of energy carried in the particle
|
|
If the wavelength of light is short what can be proposed about the characteristics of light
|
-higher Frequency = more cycles passing through a point in one secon
-if on the spectrum of visible light closer to violet -greater energy // crests closr together |
|
Example of Photon Energy
|
violet carries more energy per photon because crests are closer to together
shorter wave lengths = higher energy |
|
What is white light?
|
White light is the effect of combining the visible colors of light in equal proportions.
|
|
What is the visible spectrum
|
The visible spectrum is the portion of the electromagnetic spectrum that is visible to (can be detected by) the human eye.
-small portion of electromagnetic spectrum |
|
Visible Spectum in terms of wavelengths and frequencies
|
A typical human eye will respond to wavelengths from about 390 to 750 nm.[1] In terms of frequency, this corresponds to a band in the vicinity of 400–790 THz.
|
|
Ranges of Electromagnetic Waves
|
-10^5m
(low enegy; radiowaves) to - 10^-16m (high energy; gamma rays) |
|
Gamma Rays
|
-electromagnetic radiation with the shortest wavelength/ highest frequency/highest energy
-high energy can damage biological molecules -produced by stars and unstable atomic nuclei on earth |
|
X Rays
|
-lower energy than gamma rays = higher wave length and lower frequency than gamma rays
-pass through substances that block physical light |
|
Ultraviolet light (UV Light)
|
-in between visible light and X-Rays
-emitted from sun can cause damage in excess |
|
Visible Light
|
-Violet(short) to Red(long)
-photons of visble light do not damage biological molecules -cause our eyes to reaarange themselves to send signals to our brains |
|
Infrared Light
|
-has longer wavelengths than visible light
-all warm bodies emit infrared light -longer wavelengths than visible light |
|
Microwaves
|
-longer wavelengths than infrared light
- lower energy per photon than visible light and infrared radiation -used for radar and microwaves -effciently absorbed by water |
|
Radiowaves
|
transmit signals (radio, television, cell phones, etc.. )
|
|
Atoms emitt color when...
|
when an atom absorbs energy-- in the form of heat, light, or electricity -- it often re-emits that energy as light
|
|
Emission Spectrum
|
The emission spectrum of a chemical element or chemical compound is the relative intensity of each frequency of electromagnetic radiation emitted by the element's atoms or the compound's molecules when they are returned to a ground state.
-constituent wavelengths |
|
continuous spectrum
|
-intensity is uninterupted or smooth across the range
|
|
What property of atoms changes the emission spectrum?
|
"Since the emission of light in atoms is related to the motions of electrons within the atoms, a model for how electrons exist in atoms muct account for these specta."
|
|
Bohrs Model
|
-electrons travel around the nucleus in circular orbits that are similiar to planetary orbits around the sun
- orbit only at fixed, specific distaces analogies- step ladder |
|
Energy of each Bohr orbit ...
|
specified by a quantum number (quantized)
|
|
Quantum Number
|
Quantum numbers describe values of conserved quantities in the dynamics of the quantum system. Perhaps the most peculiar aspect of quantum mechanics is the quantization of observable quantities. This is distinguished from classical mechanics where the values can range continuously. They often describe specifically the energies of electrons in atoms, but other possibilities include angular momentum, spin etc. Since any quantum system can have one or more quantum numbers, it is a rigorous job to list all possible quantum numbers.
|
|
Electrons in orbit
|
As long as an electron remains in a given orbit, it does not absorb or emit light, and its energy remains fixed and constant.
- farther from nucleus greater the energy |
|
Atom absorbs energy...
|
-fixed electron orbit excited to an orbit farther away
-higher away from nucleus; higher energy -new configuration less stable and electron quickly falls back or relxes into lower orbit -electron wants to be closer to nucleus -as it relaxes releases photon of light -- quantum of energy = difference between two orbits |
|
Quantum of Energy
|
-percise amount of energy
-the amount of energy it takes for a electron to get from one energy level to the next. The energy of an electron bound to an atom (at rest) is said to be quantized, which results in the stability of atoms, and of matter in general. |
|
Atom Absorbing Energy by the Numbers
|
1. Electron in fixed orbit is excited; promoted to next orbit; higher energy
2. Atom becomes less stable in new configuration 3. Electron relaxes back to lower energy orbit 4. releases a photon of light containing the quantum of energy between two orbits 5. emitted photon correlates with a wavelength 6. hence light emitted by excited atoms consists of specific lines at certain wave lengths 7. those wavelengths relate to the transistion between orbits |
|
The Hydrogen Example
|
- line at 486 nm hydrogen emission spectra corresponds with electron going from n=4 to n=2
n=3 to n=2 produces less energy shorter wave length -Tranistions between orbits that are closer together produce lower energy (longer wavelength) |
|
How did Bohrs model fail?
|
-failed to predict emisson spectra of other elements that contained more than one electron
|
|
Summarize the Bohr model
|
-Electrons exist in quantized orbits at specific, fixed energies and specific, fixed distances from the nucleus
|
|
Summarize the Bohr model
|
When energy is put into an atom, electrons are excited to higher-energy orbits
|
|
Summarize the Bohr model
|
when electrons fall from higher energy to lower energy orbits (relax) atoms emit light
Atoms emit light during the reconfiguration relaxation period following excitation |
|
Summarize the Bohr model
|
The energy (and therefore the wavelength) of the emitted light corresponds to the difference in energy between the two orbits in the transition. Since these energies are fixed and discrete, the energy (and therefore the wavelength ) of the emitted light is fixed and discrete
|
|
compare the following electrion orbit transitions
n = 3 --> n = 2 to n = 2 --> n = 1 |
the second transition will have a higher energy output; larger energy per photon; higher freq and shorter wave length
this is becase the distance between orbits closer to the nucleus are much greater than on the peripheral therfore more energy is released when the electrons relaxes to a lower energy orbit |
|
Bohr Model vs Quantum - Mechanical Model
|
Orbits vs Orbitals
specific paths vs. probability maps |
|
Revolutionary Concept introduced about the electron in the quantum model
|
-electrons do not behave like particles
-no fixed paths -obrital represents not how electron moves but the probability of where the electron may be found |
|
Bohr Model vs Quantum - Mechanical Model
|
Orbits vs Orbitals
specific paths vs. probability maps |
|
Revolutionary Concept introduced about the electron in the quantum model
|
-electrons do not behave like particles
-no fixed paths -obrital represents not how electron moves but the probability of where the electron may be found |
|
Wave - Particle Duality
|
Like photons sometimes electrons act like particles other times like waves
impossible to trace is path only predict probability |
|
Bohr model vs Quatumn model
|
orbits with different radii vs orbitals with different shapes
|
|
Wave - Particle Duality
|
Like photons sometimes electrons act like particles other times like waves
impossible to trace is path only predict probability |
|
Bohr model vs Quatumn model
|
orbits with different radii vs orbitals with different shapes
|
|
Orbitals
|
-Lowest energy orbital is 1s
|
|
Orbitals
|
-Lowest energy orbital is 1s
|
|
What does the number represent in the orbital
|
- called the principal quantum number and specifies principle shell
-higher principal quantum number higher the energy of the orbital |
|
What does the letter indicates
|
the subshell of the orbital and specifies its shape
|
|
Possible subshell letters
|
s,p,d, f
|
|
S Subshell orbital shape
|
Spherical
|
|
1s orbital analogy using dots
|
density of dots larger around nucleus
|
|
1s orbital
|
spherical representation because of symmetical distribution around nucleus
|
|
Ground state
|
Lowest energy state; single electron of hydrogen in 1s orbital
|
|
Principal quantum number 2
|
- the 2 principal shell contains to subshells s and p
|
|
Relationship between Shell number and subshell amount
|
The number of subshells in a given principal shell is equal to the value of n
|
|
Electron Configuration
|
-shows the occupation of orbitals by electrons for a particular atom
|
|
Pauli Exclusion Principle
|
-the orbitals may hold no more than two electrons with opposing spins
|
|
Electron Spin
|
fundamental property of electrons
|
|
Ordering Electrons
|
-different subshells within the same principal shell have different energies
-energy ordering is not determined by quantum number alone -4s is lower than 3d electrons will fill 4s shell before 3d shell |
|
Learning check Electron Configurations part 1
|
-electrons occupy orbitals so as to minimize the energy of the atom; therefore, lower-energy orbitals fill before higher-energy orbitals.
- each orbital hold no more than two electrons with opposing spins (Pauli exclusion principle) -Hund's Rule electrons fill in singly before pairing |