1 - atomic structure

Question 1

what is the relative charge and mass of a proton?

Answer 1

mass - 1
relative charge - +1
nucleus

Question 2

what is the relative charge and mass of a neutron?

Answer 2

mass - 1
relative charge - 0
nucleus

Question 3

what is the relative charge and mass of an electron?

Answer 3

mass - 1/1840
relative charge - -1
energy levels surrounding the nucleus

Question 4

what is the atomic number?

Answer 4

number of protons (=number of electrons)

Question 5

what is the mass number?

Answer 5

number of protons + number of neutrons

Question 6

who invented the mass spectrometer and what did it lead to the discovery of?

Answer 6

Francis Aston
differing number of neutrons in the nuclei of the atoms

Question 7

what is a mass spectrometer?

Answer 7

measures the masses of atoms and molecules
produces positive ions that are deflected by a magnetic field according to their mass to charge ratio
also calculates the relative abundance of each positive ion and displays the percentage
the positive ions could be from a + atom, + molecule or + fragments of molecules

Question 8

what shape is an s orbital?

Answer 8

sphere

Question 9

what shape is a p orbital?

Answer 9

dumbell

Question 10

what is the probability of finding an electron within an s or p orbital?

Answer 10

90% for both

Question 11

how many electrons can be found in each quantum shell?

Answer 11

first - 2
second - 8
third - 18
fourth - 32

Question 12

how many electrons can be found in each subshell?

Answer 12

s - 2
p - 6
d - 10
f - 14

Question 13

what exceptions are there when predicting electronic configurations?

Answer 13

K - one electron in 4s not 3d
Ca - two electrons in 4s not 3d
since the energy of the 4s orbital is lower than the 3d orbital for those two atoms

Question 14

what is Hund’s rule?

Answer 14

electrons will occupy orbitals singly before pairing takes place

Question 15

what is the Pauli Exclusion Principle?

Answer 15

two electrons cannot occupy the same orbital unless they have opposite spins
electron spin is usually shown by the use of upward and downward arrows

Question 16

how do atoms emit electromagnetic radiation?

Answer 16

when atoms in the gaseous state are given energy by heating them or passing an electric current through them, the electrons move to different energy levels
eventually they return back to lower energy levels and emit radiation
we can analyse the radiation using a spectroscope - shows us that atoms do not emit radiation across the whole of the electromagnetic spectrum
produces a line spectrum

Question 17

example first ionisation equation

Answer 17

A(g) –> A+(g) + e-

Question 18

ionisation energy equation

Answer 18

energy of electron when removed - energy of electron when in the orbital

Question 19

what factors affect the energy an electron has?

Answer 19

• the orbital in which the electron exists
• the nuclear charge of the atom
• the repulsion (shielding) experienced by the electron from all other electrons present

Question 20

what happens to ionisation energy across a period?

Answer 20

INCREASE
nuclear charge increases (more protons)
one more electron added to the same quantum shell each time
nuclear charge is more significant and therefore increase in first ionisation energy

Question 21

what happens to ionisation energy down a group?

Answer 21

DECREASES
nuclear charge increases
one new quantum shell added each time
outer electrons experience increased repulsion
new quantum shell and repulsion is stronger than nuclear charge therefore decrease in first ionisation energy

Question 22

what does the s block consist of?

Answer 22

group 1 and 2 - highest energy in s orbital

Question 23

what does the p block consist of?

Answer 23

groups 3 - 8 - highest energy in a p-orbital

Question 24

what does the d block consist of?

Answer 24

Sc to Zn
defined as the d subshell being filled

Question 25

how do we find the atomic radius?

Answer 25

difficult since there is not a well-defined boundary determining the distance between the two nuclei and dividing it by 2

Question 26

what happens to atomic radii across a period?

Answer 26

decreases becuase the number of protons in the nucleus increases and so does the nuclear charge

Question 27

what happens to melting and boiling points across a period?

Answer 27

decreases

Question 28

why is the ionisation of a group 3 element less than that of a group 2 element?

Answer 28

whilst g3 has a greater nuclear charge the outer electron is in the 2p orbital as opposed to the 2s in g2 so the energy to remove the electron is lower the electron in 2p also experiences more repulsion from the two inner electron sub shells

Question 29

why is the ionisation of a group 6 element less than that of a group 5 element?

Answer 29

g6 has paired electrons in the 2p orbital whereas g5 has a single electron which means there is more shielding in g6 and therefore requires less energy to remove despite g6 having a higher nuclear charge