Lecture 1: Atoms Flashcards
1
Q
What is each atom composed of?
A
- Made of a atomic nucleus(with protons and neutrons: together called nucleons) and electrons
1a. Proton: 1amu
1b. Neutron: 1amu (if atom has different neutrons: isotopes)
1c. Electron: much smaller than protons and neutrons - Charge: 1e=1.6x10^-19C
- Rutherford model says that atoms are mostly empty space with electrons orbiting a fixed, positive nucleus
2
Q
Element notation
A
- Nuclide: When the number of protons and neutrons are specified for an atom
- X (A above) (Z below)
2a. A: mass number =protons+ neutrons
2b. Z: atomic number=protons - Protons and neutrons have same mass, electrons are much smaller
- There are as many electrons as there are protons
3
Q
Atomic mass vs atomic weight
A
- Atomic weight=(average of composition)/number of isotopes=((mass of 12C x percent composition) + (mass of 13C x percent composition))/number of isotopes (2)
1a. Shown on periodic table with it being the average of the isotopes masses
4
Q
Coulomb’s law
A
- Like charges repel, opposite charges attract
- Creates these equations:
2a. Force: F=k(q1q2)/r^2
2b. Energy: U=k(q1q2)/r
2c. Potential: V=kq1/r
5
Q
Plancks
A
- Planck said that energy (E) is transferred (emitted (low energy, n down) or absorbed (high energy, n up)) as photons according to E=hf where h=7x10^-34 Js
6
Q
The Photoelectric effect
A
- Photon must have a minimum energy (work energy) in order to eject an electron (energy of ejected electron is the kinetic energy)
1a. Kinetic energy=Energy of photon-Work energy - intensity can increase by increasing number of photons or the frequency of each photon
7
Q
Line spectra
A
- Continuous spectra: rainbow in visual spectra
1a. Radiowaves-microwaves-infrared-(ROYGBIP)-ultraviolet-x rays-gamma rays
1b. Gains energy as it goes to gamma rays - Emission line spectrum: measures emitted
- Absorption line spectrum: measures all except absorbed
8
Q
The Bohr Atom
A
- Says electrons are confined to a circular orbit around the nucleus which corresponds to energy levels of electrons
1a. If energy/radiation is emitted, electron moves to lower energy
1b. If energy is absorbed, electron moves to higher energy - The Bohr model: Applies to any hydrogen like atom (atom with 1 electron)
9
Q
Ground state vs excited states
A
- Ground: when n=1, electron is at lowest energy state
1a. As n increases, the electron is in its excited states, photon is absorbed
1b. As n decreases, photon is emitted - Difference in energy between the energy states is: E=hc/wavelength
2a. H=planck, c=speed of light (3x10^8)
10
Q
Heinsenberg uncertainty principle
A
- There is a uncertainty in the position and momentum of a particle
- Momentum (p)=mv (mass*velocity)
- De broglies postulate: wavelength=h/p =h/mv
3a. Planks constant=h
11
Q
Quantum numbers
A
- Principle quantum number (n): (shell) # matches row of periodic table (except d, f)
1a. Max # of electrons in a single energy level: 2n^2 - Azimuthals quantum number (l): gives 3D shape (sub shell) (l=0->(n-1))
2a. 0=s, 1=p, 2=d, 3=f
2b. Max # of electrons in a single sub shell: 4l +2 - Magnetic quantum number (ml): gives orbital subtype from (-l to l): values=2l +1
- Spin quantum number (Ms): gives electron spin in +1/2 or -1/2
12
Q
Paulis exclusion principle
A
- Says 2 electrons occupying the same orbital have opposite spins so are paired
- No 2 electrons can share the same 4 identical quantum numbers
13
Q
Aufbau/building up principle
A
- States that electrons will occupy lower energy orbitals before higher energy orbitals
14
Q
Hunds rule
A
- All orbits must have one electron before any orbitals can obtain a second electron
- Fill spin one way in subshells before you do opposite spins
15
Q
Magnetism
A
- Diamagnetic: spin paired electrons, opposing spins , weakly repelled by external magnetic field
- Paramagnetic: not spin paired, attracted to external magnetic field
