1.1 Atomic Structure Flashcards
The subatomic particles, their charge and mass
Proton : 1 : +1
Neutron : 1. : 0
Electron : 1/1836. : -1
What is an isotope
Same number of protons. But a different number of neutrons
What is the arrangement of subatomic particles?
Protons and neutrons are held in the nucleus but a strong nuclear force. Electrostatic force of attraction holds the electrons and protons together in an atom.
What is an isotope
- Atoms with the same number of protons but a different number of electrons
- different isotopes react in exactly the same way
Niels Bohr
Positive nucleus, electrons orbit in shells
Erwin Schrödinger
Equation that electrons have the same properties of waves
James Chadwick
Discovered the neutron.
What are electrons shells
What’s the equation used to calculate the maximum number of electrons each shell/level can hold?
Maximum number of electrons = 2n^2
Where n is the number of the shell
What is an atomic orbital?
A region around the nucleus that can hold up to two electrons with opposite spins
What is the electron configuration?
Atom consists of energy levels, each consisting of sub levels.
Sub levels consist of orbitals which can each hold two electrons in opposite spins
How many orbitals, and therefore electrons, can each sub level hold?
s sub level has 1 orbital, 2 electrons
p sub level has 3 orbitals, 6 electrons
d sub level has 5 orbitals, 10 electrons
f sub level has 7 orbitals, 14 electrons
What is an electron considered to be?
A cloud of negative charge, the shape of the cloud is the shape of the orbital
What can be said about the location of an electrons
Scientists can never be completely sure of the exactly location of an electrons. The orbital shows us 95% probability of where it will be
Describe the shape of the s and p sub level
S is a sphere
P is a dumbbell
What is mass spectrometry used for?
Used to determine the relative atomic mass of separate atoms or molecules and their abundance in a sample
What are the stages of TOF mass spectrometry?
1) ionisation - converting the sample into positive ions
2) acceleration - the positive ions accelerate towards and negatively charged plate
3) drift - lighter ions travel faster and hit the detector quicker than heavier ions
4) detection - when the ions hit the detector, a current is sent through them: the greater the current, the more abundant the isotope
Which of the forces writhing the atom are the strongest
- nuclear force is stronger than electrostatic force of attraction
- this overcomes the repulsion between the protons
What is ionisation
The process of removing electrons to form ions
What are the two types of ionisation
Electron spray ionisation and electron impact ionisation
Describe the process of electron spray ionisation
- a sample is dissolved in a volatile solvent (water or methanol)
- injected through a hypodermic needle to a fine mist
- tip of the needle is attached to a high voltage positive power supply
- atom gains a proton, making them positive
- solvent evaporate away
What is the half equation for electron spray ionisation
X(g) + H+ ——> XH+ (g)
Describe electron impact ionisation
- electron gun sends high energy electrons through gaseous sample
- atoms lose an electron forming 1+ ions
What is the half equation from electron impact ionisation
x(g) + e- ——> X+(g) + 2e-
