Atomic structure Flashcards
Why is a vacuum required for in atomic structure?
To prevent interference from particles.
What are the two methods of ionisation?
Electrospray ionisation and Electron Impact.
Describe Electrospray ionisation.
The sample is dissolved in a volatile polar solvent and injected through a needle at high voltage, gaining a proton to form 1+ ions.
Equation: X(g) + H* → XH*(g)
What happens to the solvent in Electrospray ionisation?
The solvent evaporates while the XH* ions are attracted towards a negative plate and accelerated.
Describe the setup for Electrospray ionisation.
A hypodermic needle is attached to the positive terminal of a high-voltage power supply.
What is the process of Electron Impact?
High energy electrons are fired from an electron gun, knocking off an electron from each particle to form 1+ ions.
What is the result of the Electron Impact process?
Formation of 1+ ions from the gaseous sample.
An electron is knocked off each particle by the high-energy electrons.
What is the role of the negative electric plate in both ionisation methods?
Positive ions are accelerated by the negative electric plate.
What is the purpose of the electron gun in atomic structure?
To generate positive ions
What happens to positive ions during the acceleration stage?
They are accelerated by an electric field to a constant kinetic energy
How does the mass of an ion affect its velocity?
Ions with lower mass travel faster and have higher velocity; ions with higher mass travel slower and have lower velocity
What is the key equation for kinetic energy?
KE = 1/2 m v^2
In the ion drift stage, what is measured to determine the mass of the ion?
The time it takes for ions to reach a detector
What does the time of flight depend on in the ion drift stage?
Velocity, which depends on the mass of the ion
Fill in the blank: Ions with a lower mass take a _______ time to reach the detector.
shorter
