ATOMIC STRUCTURE Flashcards
define mass number
mass number= atomic number- neutron number
define atomic number
atomic number = proton number - electron number
define charge
positive corresponding to the group number for metal, negative corresponding to the group number of non metal
explain the existence of isotopes
isotopes are atoms with the same proton number and different neutron number, this means they have different mass number but the same atomic number. they have the same electronic configuration so react similarly within a chemical reaction but have different physical properties
what is mass spectrometry
the chemical analysis to allow mass of molecule or the isotope to be identified. It has the ability to give structural information and identify unknown compounds to determine relative abundance of each isotope of an element.
electro spray ionisation
sample is dissolved in volatile so gives proton forming solvent.
acceleration
positive ions are accelerated by an electric field to a constant kinetic energy.
flight tube
positive ions with small mass/ charge value have some kinetic energy as those with larger mass so are much faster.
why does each particle arrive at different times
heavier particles take longer to get past the drift region which is fed to the computer for analysis that produces electrons transferring from detector to positive ions, the size of the current is proportional to the abundance of the species
how does mass spectrometry measure the Mr
Mr of the molecule- the electron impact ionisation stage will break up and give fragments, the largest peak would be due to the whole molecule and will equal the MR, this would not happen by electro spray impact as 1peak will be equal to the MH+ so you would subtract 1 to get the Mr of the molecule
how are shells filled
they are filled according to the atomic orbital with some energy is filled individually before pairing.
what does Aufbau principle state,
the lowest energy is filled first, no more than 2 electrons can fill the atomic orbital. Within the D block the chromium and the copper are Half filling their 4s so electrons will be lost from 4s then 3p so has a lower energy level
define 1st ionisation energy
energy is needed to remove 1 electron from each atom of element in 1 mol of gaseous atom to from 1 mol of gaseous ion with a +1 charge.
define 2nd ionisation energy
enthalpy change when 1 mol of gaseous ion with a +1 charge forms 1 mol of gaseous ion with a +2 charge
what can affect ionisation energy
attraction of the nucleus,
distance of electron and nucleus,
shielding of the attraction of the nucleus
define successive ionisation energy
the pattern for element that give us important electronic structure for the element.
why will 2nd ionisation energy be greater than 1st
when the 1st electron is removed, positive ionisation energy is formed because the nuclear attraction will increase, a big jump means a change in the shell and stringer attraction so more ionisation.
define periodicity
repeating pattern across a period
why does helium have a large ionisation energy
helium has a larger ionisation energy because the 1st electron is removed from the 1st shell so has a bigger ionisation energy.
trend in ionisation energy down a group
1st ionisation will decrease down the group because as one goes down the group, the outer electrons are found in shells further from the nucleus so are more shielded and nuclear attraction will decrease.
why is there a general increase in ionisation energy across a period
electrons are being added to the same shell so it has a greater distance from the nucleus but same shielding effect, as the proton increases , nuclear attraction will increase
why does sodium has a lower first ionisation energy than neon
sodium has outer electron in 3S which is more shielded, therefore it is easier to remove the nucleus.
why does a small drop from mg to al
there is a small drop from Mg to Al because Al fills the 3p sub shell whereas Mg has outer electron in 3s sub shell. 3p is easier to remove due to shielding,
why is there a small drop from P to S
there are 4 electrons in orbit S so there is repulsion in orbitals making it slightly easier to remove
