topic 2/12- atomic structure/ionisation Flashcards
define relative atomic mass, Ar
the average mass of the isotopes in a naturally occurring sample of an element, compared to 1/12th the mass of a carbon-12 atom
what do we use to determine the Ar of an element from its isotopic composition?
mass spectrometer
what is another name for protons and neutrons?
nucleons
what do A and Z stand for in:
A
X (element)
Z
A= mass number (protons + neutrons)
Z= atomic number (protons)
Describe how colour varies along the EM spectrum
High energy/frequency = PURPLE end of spectrum
Low energy/frequency= RED end of spectrum
Describe the relationship between frequency/energy and wavelength
As frequency/energy increases, wavelength decreases
Describe the difference between a line and a continuous spectrum (2)
a continuous spectrum contains all frequencies/energies
a line spectrum contains only discrete frequencies/energies
When are emission spectra produced?
When photons are emitted by atoms as excited electrons return to a lower energy level.
When are absorption spectra produced?
When photons are absorbed by atoms as excited electrons move to a higher energy level.
How does the line emission spectrum of hydrogen provide evidence for the existence of electrons in discrete energy levels?
The lines on the emission spectrum are separate up to the convergence point, suggesting electrons can only exist at specific energy levels.
Describe the first three spectral series.
Lyman- down to/up from n=1- UV
Balmer- down to/up from n=2- Visible Light
Paschen- down to/up from n=3- Near Infrared
Describe the relationship between energy of transition and colour for the hydrogen emission spectrum
The energy of the transition is proportional to the frequency of the emitted light.
State the 4 main points of Bohr’s theory.
- Electrons can only exist at specific energy levels (shells)
- A photon of light is emitted/absorbed when electrons move between energy levels
- The energy of the photon equals the difference between the energy levels
- E=hxf so the frequency of the emitted light is proportional to its energy.
What happens to the discrete energy levels of electrons at higher energies?
They converge
How does convergence affect the emission spectrum?
It leads to the lines in the emission spectrum becoming continuous
State the sub-levels of the main energy levels in order of increasing energy
s, p, d, and f
What is the number of orbitals and electrons in the s sub-level?
1 orbital = max 2 electrons
What is the number of orbitals and electrons in the p sub-level?
3 orbitals = max. 6 electrons
What is the number of orbitals and electrons in the d sub-level?
5 orbitals= max.10 electrons
What is the number of orbitals and electrons in the f sub-level?
7 orbitals= max 14 electrons