2.2 Electrons in atoms Flashcards
What does n stand for?
It represents the energy levels
What are energy levels split into?
They are split into 4 sublevels (s, p,d,f)
What does 2s mean?
The 2 means the second main energy level and s is the atomic orbital
What is an atomic orbital?
Represents region of space where there is high possibility of finding an electron
What shape are s orbitals?
They are spherical
How many p orbitals are there and what shape are they?
There are 3: Px, Py, Pz and they are dumbbell shaped
How many electrons can each sublevel hold?
S= 2 P= 6 D= 10 F= 14
How many orbitals does n=2 have?
4 (2s and 3 2p orbitals)
What is the Pauli exclusion principle?
States that two electrons cannot have the same quantum number i.e. two electrons can only occupy the same orbital if they have opposite spin
What is Heisenberg’s uncertainty principle?
States that it isn’t possible to know the exact position and momentum of an electron. Probability of knowing is usually 95%
What is Aufbau’s principle?
- 1st sub level has lowest energy so it is filled first
- S orbitals are filled before P orbitals and so on
- All 1s orbitals, 2s, 2p orbitals etc. are of equal energy (degenerate)
- There is overlap between 3d and 4s orbitals so 4s orbitals fill first as it has lower energy
What is electron configuration of Neon?
1s2 2s2 2p6
What is electron configuration of Calcium?
1s2 2s2 2p6 3s2 3p6 4s2
Exceptions: Electron configuration of Chromium
1s2 2s2 2p6 3s2 3p6 4s1 3d5
Exceptions: Electron configuration of Copper
1s1 2s2 2p6 3s2 3p6 4s1 3d10
How would you draw an orbital diagram for carbon?
1s2 will have 2 arrows in one box
2s2 will have 2 arrows in one box
2p6 will have three boxes where 2 are filled with one arrow and one box is empty
What is electron configuration for Ca2+?
1s2 2s2 2p6 3s2 3p6
Which orbital loses electrons first: 4s or 3d?
4s will lose electrons first
What is line spectra used for?
It is used to identify unknown elements
Relationship between energy and wavelength/frequency
As wavelength decreases and frequency increases, energy increases
What is wavelength?
Distance between two crests (metres). Represented by lamda
What is frequency?
Number of waves that pass a point in one second (Hz)
How do you calculate speed of light?
Wavelength x frequency
Compare frequency and wavelength of UV and infrared
UV has higher frequency and shorter wavelength while infrared has shorter frequency and longer wavelength.
Which has higher energy: UV or infrared?
UV as it has higher frequency
What is the continuous spectrum?
It shows all wavelengths or frequencies of visible light
Absorption line spectrum
Shows wavelengths that are missing in the form of black lines/stripes
Emission line spectrum
Shows difference in energy levels through coloured lines
What happens when high voltage is passed through a gas?
Electrons become excited and transition to higher energy levels by absorbing energy (ALS). When they fall back, there is emission of energy (ELS)
What is the equation for energy using frequency?
E= hf where h is Planck’s constant and f is frequency
What is Planck’s constant?
6.64 x 10^34 Js
Do energy levels get closer or farther as they increase?
Closer
What is visible emission line spectrum?
They are a set of 4 lines that converge at high frequency
What does it represent when electrons move back to n=1 (ground state)?
UV radiation
Which n do electrons return to in visible light and infrared?
n=2 and n=3 respectively
