Atomic Structure

Question 1

1st Atomic Structure (Dalton)

Answer 1

Elements were indivisible atoms.
All atoms of an element had the same mass
Different elements had different masses

Question 2

2nd atomic structure (Thomson)

Answer 2

Plum pudding model
Negatively charged electrons embedded in sphere of positive charge
Electrons were negative and light so there had to be something possible and heavier

Question 3

3rd Atomic Structure (Rutherford)

Answer 3

Most of the mass and all the positive charge was in the nucleus at the centre of the atom
e orbit nucleus
Nuclear model

Question 4

4th Atomic Structrure (Bohr)

Answer 4

e orbit nucleus in shells

Question 5

5th Atomic Structure (Chadwick)

Answer 5

Discovered the neutron

Question 6

Relative mass and charge of subatomic particles

Answer 6

p: 1, +1

n: 1,0

e: 1/1840, -1

Question 7

Describe strong nuclear force

Answer 7

Hold protons & neutrons together
Stronger than electrostatic forces
Overcomes the repulsion

Question 8

Define Isotopes

Answer 8

Atoms of the same element with the same number of protons but different number of neutrons

Question 9

Reaction of isotopes

Answer 9

Of the same element they chemically react in the same way Same electron configuration

Question 10

What can Dalton’s model explain

Answer 10

Geometry of crystals

Question 11

What can Bohr’s model explain

Answer 11

Simple model of Ionic and covalent bonding

Question 12

number of e in shells

Answer 12

= 2n²
Shell 3 has 18 e

Question 13

What’s mass spectrometer used for

Answer 13

Determining Ar

Question 14

Define Ar

Answer 14

Average mass of 1 atom of an element / 1/12 mass of a C12 atoms

Question 15

Define Mr

Answer 15

Average mass of 1 a molecule / 1/12 mass of a C12 atoms

Question 16

What happens in TOF mass spec (generally)

Answer 16

Substance converted to +ions
Accelerated
Hit detector

Question 17

What does the acceleration of ion depend on

Answer 17

Mass to charge ratio

Question 18

Why is the mass spec a vacuum

Answer 18

To prevent ions colliding with air molecules

Question 19

How does electrospray ionise atoms

Answer 19

Sample dissolved in volatile solvent
Put through fine hollow needle that’s connected to high voltage power supply
Gains proton

Question 20

Hoe does electron impact ionise atoms

Answer 20

Sample is vaporised
Electron gun fires high energy e at it
Knocks e of particle forming 1+ ion

Question 21

Equation for electrospray ionisation

Answer 21

X(g) + H^+ —> XH^+(g)

Question 22

Equation for electron impact ionisation

Answer 22

X(g) + e^- —> X^+ + 2e^-

Question 23

Acceleration (mass spec)

Answer 23

+ions attracted to negative plate and accelerated towards it
Lighter and more highly charged ions have higher speed (mass to charge ration)

Question 24

Ion drift (mass spec)

Answer 24

Ions pass through hole in negative plate and travel along flight tube

Question 25

Detection (mass spec)

Answer 25

When ions with same charge hit negative plate lighter ones are first Higher velocities Flight time recorded +ions pick up e from detector causing current to flow Abundance ∝ size of current

Question 26

Data analysis (mass spec)

Answer 26

Signal form detector passed to computer to make mass spectrum

Question 27

Relative atomic mass = ?

Answer 27

Mass number x relative abundance / 100(how many atoms there are)

Question 28

Difference between shells and sub levels

Answer 28

Energy levels (shells) divided into sub levels

Question 29

Energy of levels

Answer 29

Increases 3d has highest energy

Question 30

s, p and d orbitals

Answer 30

s orbital = 2e p orbital = 2e P sub level = 6 (groups of 3) d orbital = 2e d sub level = 10 (groups of 5)

Question 31

What’s spin

Answer 31

Property of e 2 e in same orbital have opposite spin

Question 32

Rules for writing electron configuration

Answer 32

Lower energy orbitals filled first Lower energy sub levels filled first Orbitals fill single before pairing 4s filled before 3d bc it has lower energy

Question 33

How do u know which element is in which block

Answer 33

Highest energy / last e in that orbital

Question 34

Define ionisation energy

Answer 34

Energy required to remove one mole of e from a mole of atoms in the gaseous state

Question 35

Trend in IE across period

Answer 35

Increases Nuclear charge increases Shielding is same Stronger attraction between between nucleus and outer e More difficult to remove e

Question 36

What happens in IE trend from Mg to Al

Answer 36

Al has lower IE Outer e in 3p orbital has higher energy / further from nucleus than 3s orbital So needs less energy to remove e

Question 37

What happens in IE trend from Ph to S

Answer 37

S has lower IE S has pair of e in 3p orbital repel Less energy needed to remove e

Question 38

Trend in IE down group

Answer 38

Decreases Shielding increases Easier to remove outer e