Atomic Structure Flashcards
Who created the latest model of an atom
Bohr
Mass and charge of fundamental particles
Protons = +1 1
Nuetrons = 0, 1
Electrons =-1,1/1840
Atomic number
The atomic number is equal to the number of protons
Mass number
The number of protons and neutrons combined
Isotopes
Same number of protons but different neutrons.
They have the same chemical properties because they have the same electronic configuration.
How to workout number of neutrons
Mass number-atomic number
Positive ions( cations )
Atom that has lost electrons so more protons than electrons
Negative ions ( anion )
Atom has gained electrons more electrons than protons
Rutherford experiment
Rutherford fired helium 2+ ions at a sheet of gold foil
When they arrived at point P concluded that most of the atom as empty space but a small number was detected at point Q which meant that the atom must have a small positive nucleus
Ionisation energy definition
Amount of energy required to remove one wall of electrons from one mole of atoms in the gas state
Kjmol-1
Write an equation for first and second ionisation energy for potassium
K (g) = k+(g) + e-
K+(g) = k2+(g) -e-
Three factors that affect ionisation energy
Shielding
Nuclear charge
Distance from nucleus
Why is the second ionisation energy higher than the first?
The second electron is being removed from an ion that already has a positive charge
Increase between ionisation energies
Largest increase between fourth and fifth ionisation energy
Fifth electron is closer to the nucleus
Element must have four electrons on its outer shell
Two exceptions when writing configurations and why?
Copper and chromium as the d sub shell is more stable half full or full
Exception when removing electrons
Remove in ascending order, so remove electrons from 4S subshell before 3-D
Exception for trend in ionisation energy
3-D one and 3-D four and electron orbitals repel in P4 and in P1 further away from the nucleus
Two factors that mass spectrometry measures
Relative abundance
Mass /charge ratio
Timeline of how mass spectrometry works
- Vacuum = in Time Machine is vacuumed to prevent any particles colliding from molecules from the air.
- Ionisation= electron impact or electrospray. They both gain a positive charge
- Ion drift=. Positively charged ions will be attracted to negatively charge plate. Same kinetic energy but different speeds as particles with smaller mass go faster whereas particles with higher mass have a slower velocity
- Detection= a current is induced where the ion gains a electron and is proportional to abundance
Electron impact
- Sample is vaporised.
- High energy electrons from electron gun are fired
- This knocks one electron are from each particle forming a 1+ ion
X(g) + e- = X+ (g) + 2e-
Electro spray ionisation
- Sample is dissolved in a volatile solvent.
- Injected through a fine hypodermic needle
- The tip of the needle is attached to a positive terminal of high voltage power supply
- Particles are ionised by gaining a proton
X (l) + H+ = XH+ (g)
Three equations you need to know for kinetic energy questions
KE =1/2 x M x v2
V = l/t
Mass (kg) = atomic number /avagardoes constant/1000
