Atomic Structure & Mass Flashcards
What is the flame test?
A qualitative test used to determine the presence of a metal ion in an ionic compound.
Summarise the Bohr model.
The Bohr model proposes that electrons occupy shells which are discrete (quantised) energy levels or shells. The energy levels increase with increasing distance from the nucleus.
What is “ground state?”
When an electron resides in the place where it is naturally said to be.
Differentiate between excitation and relaxation.
Excitation (absorprtion) occurs when an electron jumps up from one energy shell to another by absorbing the energy provided.
Relaxation (emission) occurs when an electron relaxes back down into its original shell, emitting light in the process.
Explain how different elements produce different colours in the flame test.
The heat of flame excites electrons to higher energy shells. As the electrons relax back down into their original shells, wavelengths of light that match the energy gaps between the lower and higher energy shells are emitted. Different elements have different numbers of protons and electrons, which changes the energies of the shell and therefore the energy gaps are different for different elements. The color results from the combination of the unique wavelengths produced by each element.
What is Pauli exclusion principle?
No more than two electrons can occupy each atomic orbital, and the two electrons must be of opposite spin.
What is AUFBAU principle?
Electrons will occupy the lowest available energy level first.
What is Hund’s rule?
Electrons will occupty empty atomic orbitals before pairing up with others.
Seats on a bus rule.
What stops alpha, beta and gamma radiation respectively?
Alpha: a thin sheet of paper
Beta: 5mm of aluminum
Gamma: thick lead
You generally find radioisotopes for elements with an atomic number that is…?
Greater than 82.
True or false: radioisotopes are rarely found in nature and are instead found as artifical isotopes.
True.
Why are there no isotopes that exist beyond the proton number of 83?
Because at that point, the strong nuclear forces that hold the nucleus together can no longer overcome the repulsive forces between the positive charges of the protons inside the nucleus.
Identify the limitations of the Bohr model.
The shell model:
* cannot accurately predict the emission spectra of atoms with more than one electron
* is unable to explain why electron shells can only hold 2 n2 electrons
* does not explain why the fourth shell accepts two electrons before the third shell is completely filled.
What is emission spectra?
Emission spectra refers to the phenomena where electrons relaxing back down into ground state after entering a state of excitation release energy in the form of electromagnetic waves. These electromagnetic waves can then be collected and processed to form the specific atom’s emission spectra
Outline the key properties of alpha, beta and gamma decay. Discuss ionisation ability and penetrating power in your answer.
Ionisation Energy
- Alpha: Strong
- Beta: Moderate
- Gamma: Weak
Penetrating Power
- Alpha: Weak
- Beta: Moderate
- Gamma: Strong
