ATOMIC STRUCTURE

Question 1

define mass number

Answer 1

mass number= atomic number- neutron number

Question 2

define atomic number

Answer 2

atomic number = proton number - electron number

Question 3

define charge

Answer 3

positive corresponding to the group number for metal, negative corresponding to the group number of non metal

Question 4

explain the existence of isotopes

Answer 4

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

Question 5

what is mass spectrometry

Answer 5

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.

Question 6

electro spray ionisation

Answer 6

sample is dissolved in volatile so gives proton forming solvent.

Question 7

acceleration

Answer 7

positive ions are accelerated by an electric field to a constant kinetic energy.

Question 8

flight tube

Answer 8

positive ions with small mass/ charge value have some kinetic energy as those with larger mass so are much faster.

Question 9

why does each particle arrive at different times

Answer 9

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

Question 10

how does mass spectrometry measure the Mr

Answer 10

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

Question 11

how are shells filled

Answer 11

they are filled according to the atomic orbital with some energy is filled individually before pairing.

Question 12

what does Aufbau principle state,

Answer 12

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

Question 13

define 1st ionisation energy

Answer 13

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.

Question 14

define 2nd ionisation energy

Answer 14

enthalpy change when 1 mol of gaseous ion with a +1 charge forms 1 mol of gaseous ion with a +2 charge

Question 15

what can affect ionisation energy

Answer 15

attraction of the nucleus,
distance of electron and nucleus,
shielding of the attraction of the nucleus

Question 16

define successive ionisation energy

Answer 16

the pattern for element that give us important electronic structure for the element.

Question 17

why will 2nd ionisation energy be greater than 1st

Answer 17

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.

Question 18

define periodicity

Answer 18

repeating pattern across a period

Question 19

why does helium have a large ionisation energy

Answer 19

helium has a larger ionisation energy because the 1st electron is removed from the 1st shell so has a bigger ionisation energy.

Question 20

trend in ionisation energy down a group

Answer 20

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.

Question 21

why is there a general increase in ionisation energy across a period

Answer 21

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

Question 22

why does sodium has a lower first ionisation energy than neon

Answer 22

sodium has outer electron in 3S which is more shielded, therefore it is easier to remove the nucleus.

Question 23

why does a small drop from mg to al

Answer 23

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,

Question 24

why is there a small drop from P to S

Answer 24

there are 4 electrons in orbit S so there is repulsion in orbitals making it slightly easier to remove