Atomic Structure Flashcards
What was Dalton’s model of the atom?
Billiard Ball
- all atoms of the same element have the same mass and are the same
- tiny
- indivisible
What was JJ Thompson’s model of the atom?
Plum Pudding
- discovered the electron
- negatively charged electrons floating in a ‘sea’ of positive charge
What was Rutherford’s model of the atom?
- discovered the nucleus
- holds most of the mass in a tiny centre with positive charge
- lots of empty space
How did Rutherford prove his model?
Gold foil experiment
- shooting alpha particles at some gold foil and seeing how many particles deflect and where they go
What was Bohr’s model of the atom?
- discovered energy shells
- each shell is fixed and has a fixed energy level
- electromagnetic radiation is either absorbed or emitted when an electron moves shell
What was Chadwick’s model of the atom?
- discovered the neutron
- a sub-atomic particle with neutral charge that is in the nucleus
what is the charge on a proton?
+ 1.6 x 10⁻¹⁹
what is the charge on neutron?
0
what is the charge on an electron?
- 1.6 x 10⁻¹⁹
what is the mass (kg) of a proton?
1.67 x 10⁻²⁷
what is the mass (kg) of a neutron?
1.67 x 10⁻²⁷
what is the mass (kg) of an electron?
9.11 x 10⁻³¹
what is the relative masses of p, n and e?
p = +1
n = +1
e = 1/1836
what is the relative charges of p, n and e?
p = +1
n = 0
e = -1
what is an isotope?
atoms of the same element, which therefore have the same number of protons and electrons, but have a different number of neutrons
what is relative atomic mass (Ar)?
the average mass of an atom of an element compared to the 1/12 the mass of a carbon-12 isotope
how to calculate Ar?
(isotope mass x %abundance) / 100
how to calculate Mr?
(mass1 x y) + (mass2 x (100 - y)) / 100
e.g. (203 x y) + (205 x (100 - y)) / 100
y = 30
what is relative molecular mass (Mr)?
the average mass of a molecule relative to one twelfth of the mass of an atom of carbon-12.
how can you measure the mass and abundance of each isotope in an element (Ar) or to find the relative molecular mass of a substance?
Time of Flight (TOF) Mass Spectrometer
what are the 5 phases of mass spectrometry?
- ionisation
- acceleration
- ion drift
- detection
- data analysis
what are the two methods of ionisation (mass spectrometry)?
- electrospray - particles gain a proton
X(g) + H⁺ -> XH⁺(g) - electron bombardment - an electron is knocked off
X(g) -> X⁺(g) + e⁻
which method of ionisation is better for larger particles?
electrospray
which method of ionisation is better for smaller particles?
electron bombardment
