Atomic Structure Flashcards
Proton relative mass and charge
1 and +1
Neutron
1 and 0
Electron
1/1840 and -1
What is the atomic number
Number of protons in nucleus
Mass number
Total number of protons and neutrons
What are isotopes
Atoms with same number of protons but different number of neutrons
What are isotopes
Atoms with same number of protons but different number of neutrons
Why do isotopes have similar chemical properties but different physical properties
They have the same chemical properties as they have the same electronic structure but different physical properties as they have different masses
What is the use of a mass spectrometer
Identify elements
Determine relative molecular mass
What is the condition for mass spectrometer
VACCUM
If not, air particles would ionise and register on detector
4 steps of a mass spectrometer
Ionisation - broken down into electron impact and electron spray
Acceleration
Drift
Detection
Explain ionisation in terms of electron impact
Vaporised sample is injected at low pressure.
Electron gun fires high energy electrons in the sample.
This knocks out an electron which forms a positive ion with different charges
Explain ionisation in terms of electron spray
Sample is dissolved in a volatile polar solvent
Sample is injected through a fine hypodermic needle which produces a fine mist /aerosol
Needles tip has high voltage so as molecule passes through it gains a proton, producing MH+
Solvent evaporates and MH+ ion moves towards negative plate
What is fragmentation
When a molecular ion breaks into smaller ions/neutral ions/radicals ~ fragments
What is fragmentation
When a molecular ion breaks into smaller ions/neutral ions/radicals ~ fragments
What is electron impact used for and does it cause fragmentation
Elements/ substances with low formula mass, it can cause fragmentation