1.1 Atomic Structure (part 1) Flashcards
What subatomic particles are atoms made up of
Protons, neutrons and electrons
What is the charge, mass and location of a proton?
Charge: +1
Mass: 1
Location: nucleus
What is the charge, mass and location of a neutron?
Mass: 1
Charge: 0
Location: nucleus
What is the charge, mass and location of an electron?
Mass: 1/2000
Charge: -1
Location: shells
Atomic number definition
Number of protons in the nucleus of an atom
Mass number definition
Number of protons and neutrons in the nucleus of an atom
Isotope
Atoms of the same element with a different number of neutrons
Why do isotopes have the same chemical properties?
Same no of elections> same electron configuration> dictates chemical behaviour
What is formed when an atom loses electrons
Positively charged ion (cation)
What is formed what an atom gains electrons?
A negative ion (anion)
What is mass spectrometry used for?
Determining information about elements and compounds, it can be used to calculate relative atomic mass of an electrons or relative molecular mass of a compound
What are the four stages of mass spectrometry
- ionisation
- acceleration
- separation of ions
- detection
What two methods of ionisation are there
Electron impact and electrospray ionisation
What are the 3 stages of electron impact ionisation
- sample injected into spectrometer and vaporised
- high energy electrons from electron gun fired at sample
- high energy electrons knock off an electron from each particle to form positive ions
What would the equation be if gaseous sodium was ionised by electron impact ionisation
Na (g) -> Na+ + e-
What are the 4 stages of electrospray ionisation?
- sample dissolved in polar solvent
- injected through a fine hypodermic needle to give a fine mist
- tip of needle is attached to the positive terminal of a high voltage supply
- particles gain a proton (H+ ion) from the solvent to form positive ions
What would the equation by if methane was ionised by electrospray ionisation
CH4 + H+ -> CH5+
What is the mass of the ion after electron impact ionisation
Mass of ion= mass of element/compound
What would the mass of an ion be if it was ionised by electrospray ionisation?
Mass of ion = mass of element/compound +1
What happens in acceleration?
An electric field is applied to accelerate the positive ions. This gives all the ions with the same charge the same kinetic energy
Do lighter or heavier ions travel faster
Lighter
What happens in seperation?
Lighter ions reach the detector first
Heavier ions reach the detector last
Why is the spectrometer kept under a vacuum?
To prevent other molecules in air colliding with the sample ions
What does a detector do
Records the different ions as they arrive at the detector
