Unit 1 AoS2- Materials Flashcards
(100 cards)
1
Q
Formula of Silver?
A
Ag+
2
Q
Formula of Copper (I) /Cupprous?
A
Cu+
3
Q
Formula of Ammonium?
A
NH4+
4
Q
Formula of Zinc?
A
Zn2+
5
Q
Formula of Copper (II)/Cuppric?
A
Cu2+
6
Q
Formula of Iron (II)/Ferrous?
A
Fe2+
7
Q
Formula of Iron (III)/Ferric?
A
Fe3+
8
Q
Formula of Hydroxide?
A
OH-
9
Q
Formula of Nitrite?
A
NO2 -
10
Q
Formula of Nitrate?
A
NO3 -
11
Q
Formula of Ethanoate?
A
CH3COO-
12
Q
Formula of Sulfite?
A
SO3 2-
13
Q
Formula of Sulfate?
A
SO4 2-
14
Q
Formula of Carbonate?
A
CO3 2-
15
Q
Formula of Hydrogen Phosphate?
A
HPO4 2-
16
Q
Formula of Dichromate?
A
Cr2O7 2-
17
Q
Formula of Phosphate?
A
PO4 3-
18
Q
Formula of Permanganate?
A
MnO4 -
19
Q
Formula of Hydrogen Sulfide?
A
HS-
20
Q
Formula of Hydrogen Sulfite?
A
HSO3 -
21
Q
Formula of Hydrogen Sulfate?
A
HSO4 -
22
Q
Formula of Hydrogen Carbonate?
A
HCO3 -
23
Q
Formula of Dihydrogen phosphate?
A
H2PO4 -
24
Q
Formula of Chromium (III)
A
Cr3+
25
Formula of Tin (II)
Sn2+
26
Formula of Lead (II)
Pb2+
27
Formula of Nickel (II)
Ni2+
28
Formula of Mercury (II)
Hg2+
29
Formula of Fluoride?
F-
30
Formula of Bromide?
Br-
31
Formula of Barium?
Ba2+
32
Formula of Nitride?
N3-
33
What are the properties of metals?
* Conduct electricity in the solid state
* Malleable and ductile
* Generally have high densities
* Tend to have high boiling temperatures
* Lustrous or reflective
* Very high tensile strength
34
What is the metallic bonding model?
A model where positive ions are arranged in a closely packed structure ( a regular three dimensional lattice of positive ions)
* The ions occupy fixed positions in the lattice. The negatively charged electrons (that have been released from the outer shell of the metal atom) are free to move throughout the lattice (delocalised electrons)
* The electrostatic attraction force between the metal ions and the delocalised electrons is known as metallic bonding.
35
What is a substitutional alloy?
Alloys made from elements that have similar chemical properties and atomic sizes.
36
What is an interstitial alloy?
Alloys made from elements that have significantly smaller atomic sizes mixed with the metals.
37
What are the 3 forms of heat treatment?
1) Annealing
2) Quenching
3) Tempering
38
What is annealing?
* When the metal is heated to a moderate temperature and then left to cool slowly.
* Larger crystals form and the metal produced is softer and more ductile.
39
What is quenching?
* The metal is heated to a moderate temperature and is cooled quickly (quenched) to form tiny crystals.
* Tiny metal crystals form and metal produced is hardened ad becomes brittle.
40
What is tempering?
* Quenched metals are warmed again but to a much lower temperature.
* Intermediate sized crystals form and metal retains hardness but brittleness is reduced.
41
What are the properties of ionic compounds?
* Does not conduct electricity in the solid state.
* Can conduct electricity in the aqueous or molten state.
* High melting and boiling temperatures.
* Hard and brittle crystals.
42
What is the Ionic Bonding model?
The large number of positive and negative ions arranged in a regular three- dimensional lattice, held together by strong electrostatic attraction between positive and negative ions is known as ionic bonding.
43
Why are ionic compounds brittle substances?
When the layers of ions move, ions of similar/like charge will become adjacent to each other. The resulting repulsion will cause the crystal to shatter.
44
What are allotropes?
Different physical forms of an element.
45
Allotropes of carbon?
* Graphite-'lead pencils’, in some batteries, dry lubricant, sporting fibres
* Diamond- valuable jewellery
* Charcoal- fuel fires, drawing
46
Which allotrope of carbon can conduct electricity?
Graphite has a free moving electron at each Carbon atom, therefore it can conduct electricity. Diamonds can't.
47
In what ways can molecules be represented as?
* Electron dot formula
| * Valence formula
48
What is minimum repulsion?
The way atoms are arranged in molecules to minimise the repulsion between the electron pairs and achieve the most stable arrangement with minimum energy.
49
What are the six shapes of the molecules?
1) Tetrahedral
2) Triangular pyramid
3) Bent/V-shaped
4) Linear
5) Planer triangle
6) Octahedral
50
An easy way to identify most tetrahedral- shaped molecules?
Only 4 bonds around the central atom.
51
An easy way to identify most triangular pyramid- shaped molecules?
Only 3 bonds + 1 lone pair around the central atom.
52
An easy way to identify most bent/V-shaped molecules?
Only 2 bonds + 2 lone pairs.
53
An easy way to identify most linear- shaped molecules?
Diatomic molecules (exceptions are CS2 and CO2)
54
An easy way to identify most planer triangle molecules?
* Only 3 bonds around the central atom.
| * Molecule does not obey the Octet rule (not achieving 8 electrons in valence shell)
55
An easy way to identify most octahedral- shaped molecules?
* Only 6 bonds around the central atom.
| * Molecule does not obey the Octet rule (not achieving 8 electrons in valence shell)
56
What are the 3 types of intramolecular forces within molecules?
* Metallic
* Ionic
* Covalent
57
What are the 3 types of intermolecular forces between molecules?
* Hydrogen bonds
* Dipole-dipole bonds
* Dispersion forces (Vanderwaal's force)
58
Which 2 shapes of molecules are always polar?
Triangular pyramid molecules and bent/V-shaped molecules.
59
What are the two conditions that must be satisfied if a molecule is to be a dipolar/polar molecule?
1) It must have polar bonds (difference in electronegativity values between the atoms)
2) The partial charges must be distributed asymmetrically across the molecule (ie the molecule must not be symmetrical)
60
What is a polarised bond (polar bond)?
When there is an electronegativity difference greater than 0.3 between the atoms in a molecule.
61
What types of bonds can there be between two polar molecules?
1) Hydrogen bonds
and/or
2) Dipole- dipole bonds
3) Dispersion forces
62
What is the order of repulsions in the VSEPR model?
lone-lone pair repulsion > lone-bond pair repulsion > bond-bond pair repulsion
63
Between which elements in polar molecules are there hydrogen bonds?
Between H and F, O, N (since these elements have the higher electronegativity values)
64
Between which elements in polar molecules are there dipole-dipole bonds?
Between any elements in polar molecules excluding H and N, O, F.
65
What results in dispersion forces between molecules?
Dispersion forces arise as a result of momentary polarisation of the atom or molecule.
66
When will there be stronger dispersion forces?
If there is a bigger electron cloud (ie in a longer carbon chain) there are stronger dispersion forces.
67
What force operates in all substances?
Dispersion forces (weakest bonding forces)
68
What is the order of the strength of intermolecular bonds?
Hydrogen bonds > dipole-dipole bonds > dispersion forces
69
To what group do soft metals belong to?
Group 1- Alkali Metals
70
What is the melting point of a metal usually based on?
The melting point depends on the energy needed to overcome the electrostatic forces between the positive ions and the delocalised electrons.
71
Why are metals good conductors of heat?
When delocalised electrons bump into each other and into metal ions, they transfer energy to their neighbour. Heating a metal gives the positive ions and electrons more energy and they vibrate more rapidly. Mobile electrons transmit this energy rapidly throughout the lattice.
72
Why are metals usually lustrous?
Because of presence of free electrons in their lattice, metals reflect light and appear shiny.
73
What is work hardening?
Hammering or working cold metals causing rearrangement of crystal grains and hardening of metal.
74
What is an ion-dipole force?
* An ion-dipole force is an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole. (ie NaCl in H2O)
* Ion-dipole attractions become stronger as either the charge on the ion increases, or as the magnitude of the dipole of the polar molecule increases.
75
How are dispersion forces formed?
They are formed due to the instantaneous dipoles created as electrons are moving around the atoms. (momentary polarisation)
76
Why do covalent networks and lattices have high melting temperatures?
* Strong forces (covalent bonds = intramolecular force) throughout lattice
* Need a huge amount energy to separate atoms
77
Why do small covalent molecular substances have low melting temperatures?
* Dispersion forces (intermolecular forces) between individual molecules are weak
* Little energy to separate molecules
78
Why do small covalent molecular substances not conduct electricity?
* Covalent molecules have no overall charge--> electric current cannot pass through
* There are no delocalised electrons or charged particles that are free to move
79
Why can't covalent network lattices conduct electricity?
All atoms localised (no free moving e-s)
80
Why can covalent layer lattices conduct electricity?
Some substances have delocalised electrons that are free to move.
81
Are small covalent molecular substances hard or soft?
* Molecules have fixed positions so are hard when solid (e.g. ice)
* Weak dispersion forces (intermolecular forces) between molecules so liquids or gases at room temperature
82
Are covalent network lattices hard or soft?
*Hard due to strong covalent bonds.
83
Are covalent layer lattices hard or soft?
* Soft/greasy (one dimension)
| * Layers can slide
84
Why do covalent network lattices and layer lattices sublime?
*high melting/decomposition temp--> all bonds break--> atoms free to move independently (solid-->gas (sublime))
85
Why do small covalent molecular substances have a low melting temperature?
intermolecular forces are weak--> small amount of energy needed to disrupt intermolecular forces --> low melting temp
86
Reactivity of covalent network lattice and covalent layer lattice?
* Very hard to disrupt a covalent bond
* Covalent network lattices (diamond, silica) do not react readily
* Covalent layer lattice (graphite) also very unreactive
87
Reactivity of small covalent molecular substances?
Small covalent molecules are more reactive but reactivity depends on strength and stability of bond
88
Account for difference between melting/boiling temperatures in various covalent substances?
If a substance has more electrons, there will be greater dispersion forces needing more energy to break the covalent bonds.
89
Account for difference between melting/boiling temperatures in various metallic substances?
If the atomic size is smaller, there is greater nuclear attraction and the electrostatic forces of attraction would be greater between the delocalised electrons and the cations, so greater energy is required to break the intermolecular interactions.
90
Account for difference between melting/boiling temperatures in various ionic substances?
The strength of electrostatic attraction between ions will depend on the size of the ions and on their charge. IF ion is smaller (greater nuclear attraction) and has a greater charge, more energy will be required to overcome the intermolecular interactions.
91
What is an alloy?
A substance formed when other materials (ie carbon and other metals) are mixed with a metal.
92
Members of the same homologous series have?
* Similar chemical properties
| * Each member differs from the previous in the series by –CH2
93
Isomers
* Isomers are organic molecules that have the same molecular formula but a different structural formula.
* Structural Isomers have different names and different chemical properties.
* This is because the molecules have different shapes.
94
Alkenes
* The Alkene series is a family of Hydrocarbons that has at least one double bond.
* Ethene is the first member in the family.
* The suffix ‘–ene’ indicates that all hydrocarbons in this family have double bonds.
* The general formula is: CnH2n
95
Rules for naming hydrocarbons
1)Determine the longest chain of carbon atoms.
2)Determine which end is nearest to a branch, a double or triple bond.
(Note: A double or triple bond takes precedence over a branch)
3) Number the C atoms from the end chosen.
4)Name any branches first (name ending in ‘-yl’ – e.g. a methane branch becomes methyl), then the longest chain with the appropriate suffix.
--> When two or more branches occur on the same C atom, the number of the C is indicated for each branch.
--> When two or more identical branches occur on different Carbons, the prefixes ‘di-’, ‘tri-’ and ‘tetra-’ are used.
96
Alkynes
* The Alkyne series is a family of Hydrocarbons that has at least one triple bond.
* The suffix ‘–yne’ indicates that all hydrocarbons in this family have triple bonds.
* The general formula is: CnH2n-2
97
Properties of hydrocarbons
*Low melting and boiling points
-->Boiling points increase with number of C atoms in the molecule
*Very flammable
*Non-polar and so mix poorly with water
*Become less volatile with increasing number of C atoms
Become more viscous with increasing number of C *atoms
98
The bonding between hydrocarbons?
Covalent bonding
99
Forces between hydrocarbons?
Dispersion forces
100
What happens in terms of dispersion forces when the size of the hydrocarbon increases?
Dispersion forces increase in strength as the size of the molecule increases
More energy is required to overcome these forces when the size of the molecule increase
The higher the strength of the dispersion forces the less volatile and more viscous the hydrocarbon becomes.
