Atomic structure (P1)

Question 1

define relative atomic mass

Answer 1

the average mass of an atom of an element on a scale where the mass of an atom of carbon-12 is exactly 12

Question 2

what are the 2 exceptions when it comes to electron configurations+draw them.
Atomic numbers: 24+29

Answer 2

Copper+chromium
Copper(29):1S2,2S2,2P6,3S2,3P6,4S1,3D10
Chromium(24): 1S2,2S2,2P6,3S2,3P6,4S1,3D5

Question 3

define relative molecular mass

Answer 3

average mass of a molecule on a scale on which a mass of an atom of carbon-12 is eaxctly 12

Question 4

define relative isotopic mass

Answer 4

the average mass of an atom of an isotope of an element on a scale which the mass of an atom of carbon-12 is exactly 12

Question 5

what does the mass number consist of?

Answer 5

number of protons +neutrons in the nucleus of an atom

Question 6

what does the atomic number consist of?

Answer 6

the number of protons and electrons

Question 7

how do you work out the number of neutrons

Answer 7

mass number-proton number

Question 8

what did john dalton propose about the atom(1800)

Answer 8

atoms are spheres and each element have different spheres

Question 9

what did jj thompson discover?what was his model

Answer 9

the electron, plum pudding model. electrons in a positive pudding

Question 10

what did rutherford discover after jj thompson? what did he propose about this subatomic particle and the rest of the atom?

Answer 10

discovered the nucleus-very small and positive. rest of the atom=empty in a negative cloud

Question 11

how did Rutherford come to his conclusion about the nucleus?

Answer 11

gold leaf experiment. he shot positive alpha particles at gold. most went through, small no. deflected.-hitting the pos nucleus

Question 12

what did niels bohr propose? why?

Answer 12

proposed fixed energy shells as rutherfords model of cloud of electrons would collapse into pos nucleus

Question 13

what subshell fills up first and why?

Answer 13

4s-lower energy level

Question 14

define ionisation energy.

Answer 14

the minimum amount of energy required to remove 1 mole of electrons from one mole of atoms in the gaseous state.

Question 15

what is the difference between the formation of ions between transition metals and normal elements in the way that there electrons are removed?

Answer 15

transition metals remove electrons from 4s subshell whereas others remove from highest energy level (3d)

Question 16

what is ionisation dependent on?(3)

Answer 16

-shielding
-atomic size
-nuclear charge

Question 17

what is the ionistion energy trend down groups? why?

Answer 17

atomic radii increases as you go down the group, so attraction is weaker. there is more shielding as more shells=less energy required

Question 18

what is the trend for ionisation energies across a period?

Answer 18

generally increases bc no of protons increases so attraction increases, shielding is similar but no effect

Question 19

in period 3 what are the two exceptions in ionisation energies?

Answer 19

between magnesium and aluminum
and between phosphorus and sulfur

Question 20

across period 3 why does the ionisation decrease between magnesium and aluminum when it should increase?

Answer 20

aluminiums outer electrons are in a higher energy level (3p) then magnesium(3s) therefore further away from the nucleus

Question 21

across period 3 why does ionization decrease between phosphorus and sulfur when it should increase?

Answer 21

phosphorus and sulfur both ahve electrons in the 3p orbital so shielding is the same. ionisation energy decreases as in sulfur there is 4 electrons in the 3p so electrons repel each other whereas in phosphorus there is only 3 with no repulsion, so less energy is recquired to remove an electron from sulfur as it has exisiting repulsion

Question 22

what are the 4 steps during mass spec?

Answer 22

1. ionisation
2. accelaration
3. ion drift
4. detection

Question 23

what occurs during ionisation in mass spec?

Answer 23

atoms are turned into ions through electrospray ionization or electron impact

Question 24

what occurs during electrospray ionisation

Answer 24

1. sample dissolved in a solvent
2. pushed through a high nozzle at high pressure
3. a high voltage is applied so that each atom gains a H+ ion

Question 25

what occurs during electron impact?

Answer 25

an electron gun is shot at the atoms causing an electron to be removed

Question 26

why is it important during mass spec that the atoms are ionised?

Answer 26

only ions can create a current at the detector

Question 27

what occurs during acceleration in mass spec?

Answer 27

metal plate has a negative charge which the ions accelerate towards it. all ions gain the same amount of KE

Question 28

what occurs during ion drift in mass spec?

Answer 28

ion goes down tube with a known length

Question 29

what occurs at detection in mass spec?

Answer 29

when the ion hits the negative metal plate at the end, 1+ ion picks up an electron creating an electic current. the more ions hit the plate the bigger the current at that moment

Question 30

why does chromium behave differently in the way its orbitals fill up. write the configuration

Answer 30

3d electrons=5 and 4s=1 , more stable this way