Atomic Structure Flashcards
Define the atomic no.
No. of protons in the nucleus
Define the mass no.
Total no. of protons + neutrons in the nucleus
Define isotopes
Atoms w/ same no. protons but diff no. of neutrons
What decides the physical properties of an element?
Mass of an atom
What decides the chemical properties of an element?
No. + arrangement of e-
Isotopes of an element have ____ physical properties
Diff
Why do isotopes have the same chemical properties?
Same e- configuration
Who discovered the 1st model of the atom + what was it?
- John Dalton
- Described atoms as solid spheres
- Diff. spheres made up diff. elements
Who discovered the 2nd model of the atom + what was it?
- JJ Thomson
- Plum pudding model
- Discovered e-
- Showed atoms weren’t solid + indivisible
Who discovered the 3rd model of the atom + what was it?
- Rutherford
- Nuclear model - tiny +ve charged nucleus surrounded by cloud of -ve e- - most empty
- Fired +ve charged a-particles at sheet of gold instead of being deflected, most passed straight through
Who discovered the 4th model of the atom + what was it?
- Bohr proposed e- exist in shells of fixed energy
- When e- move btw shells, electromagnetic radiation is emitted
Define the relative atomic mass (Ar)
Average mass of an atom of an element on a scale where an atom of carbon-12 is 12
Define the relative isotopic mass
Mass of an atom of an isotope of an element on scale where an atom of carbon-12 is 12
Define the relative molecular mass (Mr)
Average mass of a molecule on a scale where an atom of carbon-12 is 12
Describe how an ion is formed in a TOF mass spectrometer
- Electronspray ionisation - high v applied in polar solvent, gains H+ ion
- Electron impact ionisation - fire high energy e- at sample, knocks e- off, forming +1 ion
