Atomic Structure Flashcards
What is the charge of a proton?
+1
What is the charge of a neutron?
0
What is the charge of an electron?
-1
What is the mass of a proton?
1
What is the mass of a neutron?
1
What is the mass of an electron?
1/2000
What is the atomic number?
The number of protons in the nucleus of an atom
What is the mass number?
The number of protons and neutrons in the nucleus of an atom
What is an isotope?
Are atoms of the same element (have the same number of protons) with a different number of neutrons
Why do isotopes have the same chemical properties?
They have the same number and arrangement of outer shell electrons
What are the 4 steps in mass spectrometry?
- ionisation
- acceleration
- ion drift
- detection
What are the two ways an atom can be ionised in step one of mass spectrometry?
Electron impact and electrospray ionisation
Describe electron impact ionisation
- Sample is injected into spectrometer and vaporised
- High energy electrons from an electron gun are fired at the sample
- The high energy electrons knock off an electron from each particle to form positive ions
Write the equation for the electron impact ionisation of sodium
Na (g) —> Na+ (g) + e-(g)
Explain electrospray ionisation
- Sample is dissolved in a volatile solvent and is injected through a fine needle at high pressure
- Due to presence of high voltage at the needle the molecule gains an electron from the solvent
- The solvent evaporates and the positively charged ions are attracted towards the negative plate.
