Atomic Structure Flashcards
What is the history of the atom?
- Robert Boyle - 1661 (chemical elements)
- John Dalton - 1803 (elements consist of atoms/invisible particles)
- J J Thomson - 1897 (plum pudding model)
- Neils Bohr - 1913 (atom is orbited by electrons)
- Ernest Rutherford - 1911 (most of mass of an atom is in nucleus)
- Erwin Schrodinger - 1926 (wave equation for electron movement)
What is the mass of a proton, electron and neutron?
Proton- 1
Electron- 1/1840
Neutron- 1
What is the charge of a proton, electron and neutron?
Proton- +1
Electron- -1
Neutron- 0
What is the arrangement of sub-atomic particles?
Protons and neutrons are in the centre of the atom, held by a strong nuclear force
What is the definition of relative atomic mass?
The average mass of an atom of an element compared to 1/12th the mass of carbon 12.
What is an isotope?
An element with the same number of protons but different number of neutrons.
Why do isotopes have all the same chemical properties?
They chemically react in the same way because they have the same electron configuration.
What is the equation for the number of electrons in each shell?
2n^2 n=number of the shell
What is the relative abundance of an isotope?
Percentage of atoms with a specific atomic mass found in a naturally occurring sample of an element.
What is the purpose of mass spectrometry?
To find the relative abundance of each isotope of an element.
What does a mass spectrometer show?
A series of peaks on a graph with relative abundance of isotopes against mass/charge, this can be used to calculate relative atomic mass.
Mass spectrometry can identify elements
What are the conditions required for mass spectrometry to take place?
- In a vacuum, to prevent ions from colliding with air molecules
- Elements in a gaseous state - solids are vaporised
What are the 4 stages of mass spectrometry?
- Ionisation
- Acceleration
- Ion drift
- Detection
What occurs in ionisation / what are the two different types?
Electrospray - sample is dissolved in volatile solvent and this causes the addition of a proton
Electron impact - electrons are fired from electron gun at vaporised sample this causes an electron to be knocked off (1+ ion)
Ionisation is where atoms are converted to ions
What occurs in acceleration?
Ions are accelerated using an electric field so they have the same kinetic energy
Lighter particles have a higher velocity
What occurs in ion drift?
Ions pass through hole in negatively charged plate through flight tube
What occurs in detection?
Lighter ions arrive first due to having higher velocities
The more electrons that his the plate the larger the current and the bigger the peak
What occurs in data analysis?
Data is recorded in a mass spectrum
Why is a negatively charged plate used in mass spectrometry?
To attract positive ions
What are the 4 sub-levels? + how many electrons/orbitals do they have/hold?
s- 2 (1 orbital)
p- 6 (3 orbitals)
d- 10 (5 orbitals)
f- 14 (7 orbitals)
What is the aufbau principle?
Lowest energy sub-levels are occupied
Whats hunds rule of maximum multiplicity?
If two or more orbitals of equal energy are available the electrons will occupy them singly before becoming paired
What is the Pauli Exclusion principle?
Two electrons in the same orbital must have opposite spins (up/down arrows)
Which elements do not follow the rules of normal electronic configurations?
Chromium, Copper