Atomic Structure

Question 1

Dalton model

Answer 1

• all atoms of one element are the same

- tiny, indivisible

Question 2

Thompson model

Answer 2

• discovered electron
• plum pudding model
• electrons move in sea of positive charge

Question 3

Rutherford model

Answer 3

• most mass is in nucleus
• negative charge orbiting it
• neutral

Question 4

Bohr model

Answer 4

-electrons orbit in paths, explained different energies of electrons at different points

Question 5

Current model

Answer 5

• protons, neutrons, electrons
• P and N made of smaller quarks
• Electrons surround central nucleus

Question 6

mass number letter

Answer 6

A

Question 7

atomic number letter

Answer 7

Z

Question 8

the mass spectrometer

Answer 8

gives accurate info on relative atomic mass and relative abundance of isotopes

Question 9

what is the mass spectrometer used for

Answer 9

• identify elements
• determine relative molecular mass
• provide structural info, identify unknown compounds

Question 10

Flight mass spectrometer

Answer 10

substance converted to ions, accelerated at high speeds, arrive at detector

Question 11

why is flight mass spectrometer done in a vacuum

Answer 11

prevent ions colliding w/ air molecules

Question 12

electrospray ionisation

Answer 12

• sample dissolved in volatile solvent, forced through a fine hollow needle connected to positive terminal of a high voltage supple
• produces tiny, charged droplets (gained proton from solvent)
• solvent evaporates from droplets into a vacuum, droplets get smaller, until they contain only a single charged ion

Question 13

electron impact

Answer 13

sample vaporised, high energy electrons fired at it from an electron gun (hot wire filament w/ a current running through it that emits beam of high energy electrons). usually knocks off 1 electron from each particle, forms +1 ion

Question 14

acceleration

Answer 14

ions accelerated towards negatively charged plate to give ions constant ke, therefore velocity will depend on mass

Question 15

steps of flight mass spectrometer

Answer 15

ionisation, acceleration, ion drift, ion detection, data analysis

Question 16

ion drift

Answer 16

ions pass through hole in negatively charged plate, form a beam, travel along the flight tube to the detector

Question 17

ion detection

Answer 17

flight times recorded, ions pick up electron from detector, causes a current to flow

Question 18

data analysis

Answer 18

signal from detector passes to a computer which generated a mass spectrum

Question 19

mass spectra

Answer 19

• identify isotopes that make up element, detects individual ions, so different isotopes are identifies separately as they have different masses
• peak height= relative abidance of each isotope

Question 20

high resolution mass spectrometry

Answer 20

5 dps

Question 21

low resolution mass spectrometry

Answer 21

1 dp

mostly used

Question 22

how many electrons can each shell hold

Answer 22

2n^2

n=no. of main level

Question 23

as you get onto higher energy levels, what happens to electron energy

Answer 23

higher

Question 24

orbitals

Answer 24

s,p,d.
can hold 1 pair of electrons
different shapes, so different energies (sub-level spd)

Question 25

s orbital

Answer 25

can hold 2 electrons

Question 26

p orbital

Answer 26

2 electrons, groups of 3, each w/ same energy

6 electrons total

Question 27

d

Answer 27

groups of 5

10 electrons total

Question 28

4s and 3d

Answer 28

4s has lower energy than 3d, must be filled before

Question 29

spin

Answer 29

2 electrons in the same orbital must have opposite spins

shown by ⇵

Question 30

nXy

Answer 30

n=main shell number (1,2,3)
x=type of orbital (s,p,d)
y=no, of electrons in sub shell

Question 31

rules for configuration

Answer 31

1) atomic orbitals of lower energy filled first
2) atomic orbitals of same energy fill singly first before pairing (electron repulsion)
3) no orbital can hold >2 electrons

Question 32

ionisation energy definition

Answer 32

amount of energy required to remove 1 mole of electrons from 1 mole of atoms in the gaseous state. measured in KJmol-1

Question 33

how does atomic radii affect IE

Answer 33

larger radius, further electrons are, less nuclear attraction

Question 34

how does nuclear charge affect IE

Answer 34

greater nuclear charge= greater attraction

Question 35

how does shielding affect IE

Answer 35

electrons repel each other (negative charge). greater no. of inner shells=greater repulsion of electrons

Question 36

first IE

Answer 36

first electron needs least energy to remove; being removed from a neutral atom.
X -> X+ + e-

Question 37

nth ionisation energy

Answer 37

X(n-1)+ -> Xn+ +e-

Question 38

successive ionisation energies

Answer 38

within each shell, successive ionisation energies increase- less electron repulsion
between shells, big jumps in IE; electrons closer to nucleus

Question 39

IE across a period

Answer 39

electrons added to same shell, greater attraction

Question 40

IE down a group

Answer 40

more shells, larger nuclei, bigger atomic radius, more shielding, less attractions

Question 41

IE across period 3

Answer 41

generally increases; more nuclear charge, harder to remove electron

Question 42

why does IE decrease from Mg to Al

Answer 42

outer electron in Al is in 3p, higher than 3s; less energy to remove

Question 43

why does IE decrease from P to S

Answer 43

P: each 3p orbital has one electron
S: one 3p has 2 electrons; repulsion makes it easier to remove electron

Question 44

IE across group 2

Answer 44

• general decrease; outer electron further from nucleus

- down group, nuclear charge increases (expect it to be harder to remove), but shielding