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Chemistry Year 12 > Atoms, Electrons And Bonding, Shapes Of Molecules (Module 2)✅ > Flashcards

Atoms, Electrons And Bonding, Shapes Of Molecules (Module 2)✅ Flashcards

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1
Q

What are induced dipole dipole forces how are they formed

A

(London forces) they are present in all molecular substances, they occur because electrons are constantly moving around and there will be an uneven electron distribution, this causes a temporary dipole within a molecule

This temporary dipole induces a temporary dipole in a neighboring molecule there is then an attraction between them

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2
Q

What makes a stronger London force

A

The bigger the molecule the stronger the bonds as there are more electrons which means there are more London forces

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3
Q

When are there permanent dipole dipole attractions

A

Between polar molecules eg H-Cl molecules
Some molecules are non polar but contain polar bonds

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4
Q

What 3 atoms cause a hydrogen bond

A

N,O,F

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5
Q

How are hydrogen bonds formed

A

The polar bond between the H and N/O/F leaves the H nucleus exposed as H only has one electron.
• Therefore there is a strong attraction from the lone pair on the N/O/F of one molecule to the exposed H
nucleus of another molecule.

H is delta positive and N/O/F is delta negative

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6
Q

Give the list starting with strongest forces of attraction

A

Hydrogen bonds, permanent dipole dipole, London forces

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7
Q

When the structure type is monatomic what are the type of particles and which substances are they

A

Particles=atoms
Substances=group 0 elements

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8
Q

When the structure type is simple molecular what are the particles and which substances are they

A

Particles=molecules
Substances=most non metal expect group 0, most compounds made from non metals combined

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9
Q

When the structure type is giant covalent what are the particles and which substances are they

A

Particles=atoms
Substances=diamond, graphite,silicon, silicon dioxide

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10
Q

When the structure type is ionic what are the particles and what substances are they

A

Particles=ions
Substances=most compounds made from metals and non metals combined

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11
Q

When the structure type is metallic what are the particles and which substances are they

A

Particles=ions and delocalized electrons
Substances=metals

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12
Q

What is the atomic number

A

Number of protons and electrons if it’s not an ion
Goes below the mass number on the species eg 31P then it’s 15
15

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13
Q

What is the mass number

A

The top number
Is the number of protons and neutrons

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14
Q

How do you find the %abundance

A

%abundance=peak height/total heigh of all the peaks X100

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15
Q

How do you find the Mr using a mass spectrometer table

A

Mass number X %abundance and add up all the isotopes/100

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16
Q

Identify the species responsible for a peak at m/z 208

A

Pb 208+
82

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17
Q

How do you sketch what the mass spectrum of the element bromine of equal abundance would look like

A

158:1
160:2
162:1

81-81=152
81-79=160
79-81=160
79-79=158

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18
Q

Name the order of shells in electronic configuration

A

1s,2s,2p,3s,3p,4s,3d,4p

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19
Q

How many electrons can be held in each type of shell

A

S=2
P=6
D=10

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20
Q

What happens during mass spectrometer

A

Sample is vaporized and then ionized to form positive ions
Ions accelerated, heavier ions more difficult to reflect then lighter ones
Ions are detected on a mass spectrum as mass to charge ratio (m/z)
All ions are positive (+1)

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21
Q

What is the structure of S orbital

A

Spherical and contains 1 or 2 electrons

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22
Q

What is structure of D and F orbitals

A

D= same shape as p (dumbbell) but across 2 planes can take 10 electrons (daisy leaf)
F= same as D but across 4 planes can take 14 electrons

2 on each plane

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23
Q

Why do electrons fill up the sub shell with 1 electron first

A

Minimize repulsion and have the paired electron spin in a different direction to also minimize repulsion

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24
Q

What are the exceptions where 4s is not filled up first

A

Cooper and chromium

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25
Q

What electrons are lost first to form an ion

A

Highest energy electrons are lost first
4s is lost before 3d

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26
Q

For what type of bonding do you use square brackets for

A

Ionic

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27
Q

What happens to electrons during covalent, ionic and metallic bonding

A

Covalent=shared
Ionic=metal gives outer shell electrons
Metallic=atoms donate outer shell electrons to a shared pool

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28
Q

Do ionic compounds dissolve in polar substances

A

Most ionic compounds dissolve in polar substances like water

29
Q

What elements in group 5,6,7 expand their octet

A

5:P As
6:S,Se,Te
7:Cl,Br,I,At

30
Q

How much does a lone pair of electrons affect the bond angle by

A

-2.5 degrees

31
Q

What is the equation to determine amount of electrons in a shell

A

2n^2

32
Q

What metals have higher melting points

A

One with a greater charge and a smaller atom

33
Q

How to convert degrees to kelvin

A

+273.

34
Q

What is the ideal gas equation

A

PV=nRT

35
Q

What are the unity’s for ideal gas equation

A

P=Pa
V=M^3
N=moles
R=8.31
T=kelvin

36
Q

Describe linear shape of molecules

A

Example CO2,
Bond angle=180
Number of bonded pairs of electrons=2
Number of lone pairs=0

37
Q

Describe bent shape of molecule

A

Example water
Bond angle=104.5
Diagram=2 straight lines below horizontal
Number of bonded pairs of electrons=2
Number of lone pairs of electrons=2

38
Q

Describe trigonal planar

A

Example boron trifluoride
Diagram=3straight lines
Bond angle=120
Number of bonded pairs=3
Number of lone pairs=0

39
Q

Describe tetrahedral

A

Example=methane
Diagram=2straight lines, 1 dash,1 wedge
Bond angle=109.5
Number of bonded pairs=4
Number of lone pairs=0

40
Q

Describe pyramidal

A

Example ammonia
Diagram=1 straight line,1 wedge,1 dashed below horizontal
Number of bonded pairs=3
Number of lone pairs=1

41
Q

Describe octahedral

A

Example sulfur hexafluoride
Diagram=2wedge,2 dash, 2 straight
Bond angle=90
Number of bonded pairs=6
Number of lone pairs=0

42
Q

Describe trigonal bipyramidal

A

Bond angle:90 and 120
Tetrahedron shape

43
Q

Describe trigonal pyramidal

A

Bond angle:107
Shape triangle
3 bonded pairs of electrons
1 lone pair of electrons

44
Q

When does ionic compounds conduct electricity

A

When molten or in liquid state

45
Q

What is the relative mass of a proton neutron and electron

A

P=1
N=1
E=1/1836

46
Q

What is the definition of an isotope

A

atoms of the same element that contain the same number of protons and electrons but a different number of neutrons.

47
Q

On an element eg 16O
8
Where is the mass number whag does it represent, where is the atomic number what does it represent, what happens in isotopes

A

Mass number =16, number of protons + neutrons
Atomic number=8, number of protons
In isotopes mass number increases bud atomic number stays the same

48
Q

What is a positive ions called
What is a negative ion called

A

Cations is positive
Anions is negative

49
Q

How many protons,neutrons and electrons are in 24 Mg2+ and 35 Cl-
12. 17

A

Mg= 12P, 12N, 10E
Cl=17P, 18N, 18E

50
Q

What is relative isotopic mass

A

Mass of an isotope relative to 1/12 of the mass of an atom of carbon 12

51
Q

What is relative atomic mass

A

Weighted mean mass of an atom of an element relative to one twelfth of the mass of an atom of carbon-12

52
Q

How does a mass spectrometer work

A
  1. Sample placed in mass spectrometer
  2. Sample vaporized and then ionized to form positive ions
  3. Ions are accelerated. Heavier ions move more slowly and are more difficult to deflect than lighter ions, so the ions of each isotope are separated
  4. Ions are detected on a mass spectrum as a mass to charge ratio (m/z). Each ion reaching detector adds to the signal, so greater the abundance, the larger the signal
53
Q

What is the equation for m/z

A

M/Z=relative mass of an ion/ relative charge of an ion

54
Q

What is the principal quantum number

A

The shell number or energy level number

55
Q

What is an atomic orbital

A

A region around the nucleus that can hold up to 2 electrons, with opposite spins

56
Q

What is the structure of a p orbital, how many electrons can it take

A

Dumb-bell shape
Each shell contains 3 p orbitals

57
Q

Why is 4S filled up before 3D

A

3D sub shell is at a higher energy level then 4S

58
Q

How do you represent the spin of an electron in a shell

A

Arrows pointing different ways, 1 electron in each sub shell before there is 2

59
Q

What do square brackets in dot and cross diagrams represent

A

The charge is spread over each ion and that the ions are separate entities

60
Q

What are the 4 blocks on the periodic table and where are they

A

S= group 1,2 and helium
D= group between 2-3
P= 3-8
F= below the periodic table (not first column)

61
Q

Draw the first and second ionization energy for helium

A

He=He+ +e- First
He+ = He2+. + e- Second

Include state symbols (g)

62
Q

What does the large increase between the 7th and 8th ionization energy for fluorine suggest

A

8th electron must be removed from a different shell, closer to the nucleus and with less shielding (change from n=2 to n=1)

63
Q

What do group 3 and 6 have a slight decrease in first ionization energy

A

Marks start of electron pairing in P orbitals of the p sub shell for 6th period

64
Q

describe the development of the atomic models

A

1803=Dalton defined elements as atoms of same mass

1897=Thomson discovered electrons, development of plum pudding model

1911= Rutherford gold foil experiment, proposed idea of atomic nucleus

1913= Bohr developed nuclear model of atom

1926= Schrodinger discovered electrons can act as waves or particles

1932= chadwick discovered neutrons

65
Q

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

A

nuclear charge increases

shielding stays the same

nuclear force of attraction increases

atomic radius decreases

66
Q

what does a giant metallic lattice allow a metal to do

A

conduct electricity and heat
give it high melting and boiling points

due to strong electrostatic attraction between cations and delocalised electrons requires a large amount of energy to overcome

67
Q

what elements form solid giant covalent lattices, which ones conduct electricity and are they hard or soft

A

diamond=hard (lattice structure), doesn’t conduct

graphite=soft (layers slide over each other),conducts due to extra electron between layers

graphene=soft (layers), conducts

silicon dioxide=similar to diamond, high MP+BP, doesn’t conduct

68
Q

what are the trends in melting points

A

increases from 1-4, drops very low from 5-8

1-4 higher due to giant structures
5-8 simple structures, size of van der waal forces determines MP+BP, those with more electrons have stronger intermolecular forces

Chemistry Year 12 (5 decks)

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