Atomic Structure Flashcards
Describe the Bohr Model
Protons and electrons are found in the nucleus
Electrons orbit around the nucleus in shells / energy levels
What is the relative mass of a proton, neutron and electron?
proton = 1
neutron = 1
electron = 1/1840
What is the relative charge of a proton, neutron an electron?
proton = +1
neutron = 0
electron = -1
define atomic number
the number of protons in the nucleus
define mass number
total number of protons and neutrons in the nucleus
define isotopes
atoms with the same number of protons but different number of neutrons
why do isotopes of the same element have the same chemical properties?
they have the same electron configuration
define ionisation energy
the amount of energy needed to remove one mole of electrons from one mole of atoms, in the gaseous state
what are the units of ionisation energy?
kJ mol-1
what three factors influence ionisation energy?
nuclear charge
distance from the nucleus
shielding
why is the second ionisation energy higher than the first?
second electron removed from an ion that already has a positive charge
what is an orbital?
a region within an atom that can hold up to two electrons with opposite spins
what is the highest energy electron?
outermost electron on an atom/ion
why is the outermost electron the highest energy electron?
it is the furthest from the nucleus
when are d-block elements more stable?
when they have a full, or exactly half full subshell
what is the electron configuration of chromium?
1s2 2s2 2p6 3s2 3p6 4s1 3d5
what is the electron configuration of copper?
1s2 2s2 2p6 3s2 3p6 4s1 3d10
how does the ionisation energy change down a group?
atoms get bigger
more shielding
weaker attraction between nucleus and electron in outer shell
ionisation energy decreases down group
state and explain the trend in atomic radius down a group
atomic radius increases
outer electrons are further away from nucleus, so they are less attracted to the nucleus
why does the atomic radius get smaller from left to right across a period?
nuclear charge increases
greater attraction between the electrons and nucleus
amount of shielding stays the same
what two factors does the mass spectrometer measure?
relative abundance
mass/charge ratio
why are sample particles ionised in the mass spectrometer?
so they can be accelerated towards the negatively charged plate
so they generate a current when the hit a detector
how is the ion accelerated in the mass spectrometer?
positive ions attracted to the negatively charged plate
all ions have the same kinetic energy
how are ions separated in the flight tube in the mass spectrometer?
ions travelling at higher speeds (small m/z) move ahead of those travelling more slowly (large m/z)
how are the ions detected in the mass spectrometer?
each ion hits the detector
ion gains an electron
generates a current
size of the current is proportional to the abundance of the ion1
describe electron impact
sample is vaporised
high energy electrons fired at it from an electron gun
knocks off an electron
forming +1 ion
describe electrospray ionisation
sample dissolved in volatile solvent
injected through fine hypodermic needle
attached to the positive terminal of a high voltage power supply
particles ionised by gaining a proton
how do you calculate the Ar from mass spectrometry?
((mass 1 x abundance 1) + (mass 2 x abundance 2) + (mass n + abundance n)) / total abundance
what is the equation for calculating kinetic energy of ions in the mass spectrometer?
KE = 1/2 x m x v^2
what are the units for KE = 1/2 x m x v^2 and d = t x v
KE = J
m = Kg
V = m s-1
d = m
t = s
how do you calculate the mass of an atom, in kg, using Avogadro’s constant?
mass number / 1000 / 6.022 x 10^23
