Atomic Structure Flashcards
(23 cards)
what are isotopes?
atoms of the same element with the same number of protons but different number of neutrons
what is the atomic number?
(proton number)
number of protons in the nucleus
identifies the element
what is the mass number?
total number of protons and neutrons in the nucleus
what does the relative charge/mass table look like?
proton 1 +1
neutron 1 0
electron almost 0 -1
where is the mass concentrated in an atom?
the nucleus
what makes up most of the volume in an atom?
orbitals
define relative atomic mass
average mass of an atom of an element on a scale where carbon-12 is 12
define relative isotopic mass
mass of an isotope of an element on a scale where carbon-12 is 12
explain the difference between relative molecular mass and relative formula mass
relative formula mass is used for ionic or giant covalent compounds
to find, just add up all relative atomic masses for the atoms in the formula
describe electrospray ionisation
- ionisation
sample is dissolved and pushed through high pressure needle gaining H+ ion and turned into gas - acceleration
positive ions accelerated by electric field so all have same kinetic energy
3.ion drift
no electric field so lighter ions will drift through faster
- detection
lighter ions drift faster so will reach detector in less time
negatively charged plate detects positive ions creating a current
electron impact ionisation
- ionisation
sample is vaporised and electron gun fires high energy electrons to knock off one electron so they become +1 ions - acceleration
- ion drift
- detection
how do you calculate relative atomic mass from a mass spectrum?
times the abundance by the mass
add up each answer to the first part
divide by the overall abundance
how does a mass spectrum determine relative molecular mass?
positive ions produce a peak in spectrum with a mass/charge ratio equal to relative molecular mass
write down the sub shells up to 4p
1s 2s 2p 3s 3p 4s 3d 4p
how many electrons does each sub shell hold?
s=2
p=6
d=10
why do chromium and copper fill up their shells in a different way?
they donate one of their 4s electrons to the 3d sub shell to make it more stable
Cr = 1s2 2s2 2p6 3s2 3p6 4s1 3d5
Cu= 1s2 2s2 2p6 3s2 3p6 4s1 3d10
which groups in the periodic table gain electrons to form negative ions?
groups 5,6 and 7ncan gain 1,2 or 3 electrons
define first ionisation energy and give an equation as an example
energy needed to remove 1 electron from an atom in 1 mole in a gaseous state to form a +1 ion
O(g) > O+(g) + e-
describe the three main factors affecting ionisation energies
- Nuclear Charge
the more protons, the more positively charged the nucleus is, the stronger the attraction is between electrons and nucleus - distance from nucleus
electrons close to the nucleus have a stronger attraction then those further away
3.sheilding
the further away the electron the less attraction, the lessening of pull is called shielding
explain the relationship between ionisation energy and FoA
a high ionisation energy means a high FoA between electron and nucleus so more energy is required to remove the electron
describe the ionisation energy trend in group 2
it decreases as you go down the group
- shielding
- electrons further away less FoA
describe the ionisation energy trend across a period
ionisation energy increases
-number of protons increase
-nuclear attraction
x
1st drop is moving sub shell
3p higher energy than 3s so further away from nucleus x
2nd drop is electron repulsion x
easier to remove x
x
x
x
x
x
is it easier to remove a lone electron in an orbital or one in a pair?
it is easier to remove an electron from a shared orbital due to electron repulsion
