Atomic Structure Flashcards
What is the atomic number?
The number of protons in the nucleus of an atom
Define isotope
An isotope of an element is an atom with the same number of protons but different number of neutrons
What did John Dalton conclude?
That atoms were solid spheres and said that different spheres made up the different elements
What did J.J. Thomson conclude?
Atoms must contain even smaller, negatively charged particles. He came up with the plum pudding model where electrons were dotted around inside the positively charged ‘pudding’
What was Rutherford’s theory of the atom?
They conducted the gold foil experiment where they fired alpha particles at a sheet of gold foil. Most of the alpha particles passed straight through which disproved the plum pudding model. He said that there is a tiny positively charged nucleus at the centre and most of the atom is empty space.
What were Bohr’s 4 basic principles?
- electrons only exist in fixed orbitals
- each she’ll has a fixed energy
- when an electron moves between shells, electromagnetic radiation is emitted of absorbed
- because the energy of shells is fixed, the radiation will have a fixed frequency
What is relative atomic mass?
The relative atomic mass (Ar) is the average mass of an atom of an element on a scale where an atom of carbon-12 is exactly 12
What is relative isotopic mass?
Relative isotopic mass is the mass of an atom of an isotope of an element on a scale where an atom of carbon-12 is exactly 12
What is relative molecular mass?
(Mr) is the average mass of a molecule on a scale where an atom of carbon-12 is exactly 12
What is relative formula mass?
Relative formula mass is the average mass of a formula unit on a scale where an atom of carbon-12 is exactly 12.
What happens during the ionisation stage of mass spectrometry?
The sample is dissolved in a polar solvent and pushed through a small nozzle at a high pressure. A high voltage is applied causing the particles to lose an electron. The ionised particles are separated from the solvent, leaving a gas made up of positive ions
What happened during the acceleration stage in mass spectrometry?
The positive ions are accelerated by an electric field. The ions with a lower mass/charge ratio experience a greater acceleration even though all ions are given the same amount of energy
What happens during the ion drift stage in mass spectrometry?
The ions leave the electric field with constant speed and constant kinetic energy. They enter a region with no electric field and continue drifting with the same speed they left the electric field at. The lighter ions with drift faster
What happens during the detection stage in mass spectrometry?
The ions with a lower mass/charge ratio will travel quicker so they will hit the detector in a shorter time. The detector detects the current created when the ions hit it and records how long they took to pass through the spectrometer. This data is then used to calculate the mass/charge values needed to produce a mass spectrum
What is relative isotopic abundance (mass spectrometry)
The relative amount of each isotope present in a sample
