unit 5 + 2 - energy + bonding Flashcards
1
Q
Take in energy? (what reaction type)
A
Endothermic
2
Q
Gives out energy (what reaction type)
A
exothermic
3
Q
Increase in temp in surrounding/environment ((what reaction type)
A
exothermic
4
Q
Decrease in temp in surrounding/environment (what reaction type)
A
endothermic
5
Q
Heat is transferred from an object at high temp to a lower temp object until both of them are ……
A
equal in temp
6
Q
Bond breaking what type of reaction
A
Endothermic - absorbs energy
7
Q
Bond forming what reaction type
A
exothermic - releases energy
8
Q
Enthalpy
A
Change in Temp
9
Q
How to calculate change in enthalpy using graph and using bond enthalpy calculations
A
From graph you do: product energy - reactant energy
From bond enthalpy calculations you do:
reactants energy - products energy
10
Q
Bond Enthalpy
A
This is the energy required to break one mole of a specific bond type
11
Q
If heat is absorbed (endothermic) ΔH is
A
positive
12
Q
If heat is released (exothermic) ΔH is
A
negative
13
Q
Entropy
A
Measurement of a system’s disorder or randomness
14
Q
Entropy is most and least in
A
Most in gaseous
Least in solids
15
Q
What all is required for a thing to burn
A
Heat, oxygen and fuel (substance containing carbon)
16
Q
In which energy diagram is the product energy, less than the reactant energy
A
Exothermic (energy released is calculated by product energy - reactant energy)
17
Q
In which energy diagram is the product energy, more than the reactant energy
A
Endothermic (Energy absorbed is calculated by product energy - reactant energy)
18
Q
Products of any combustion reaction
A
Water vapour and Carbon dioxide
19
Q
Incomplete combustion
A
When there is insufficient oxygen in a combustion reaction and instead of carbon dioxide, carbon monoxide is formed
20
Q
Ignition temp
A
Min temp required for something to catch fire
21
Q
specific heat capacity
A
Amount of heat energy required to change the temperature of 1kg of a substance by 1 degree Celsius
22
Q
In an endothermic reaction, the energy needed to break existing bonds is ______________ the energy released from forming new bonds.
A
more than
23
Q
how does a co2 fire extinguisher work?
A
CO2 is hevaier tha oxygen and hence this extinguisher forms a cloud of CO2 around the fire, essentially pushing the oxygen away and without it the fire cant burn
24
Q
Bonding
A
The force of attraction between atoms so that they can be joined chemically
25
Why is bonding done
For an atom to become stable and make the outermost shell full
26
Ions
Particles which carry a +ve or -ve charge
27
Types of bonding
Metallic, Ionic, Covalent
28
Metallic bonding
Between two metals or alloys.
The atoms of a metallically bonded compound remain tightly packed in a lattice structure, with the valence electrons being separated from their atoms and becoming delocalized, forming a sea of electrons around the positive metal ions in the electron cloud
29
why dont metal ions repel each other in metllaically bonded compound?
The strong electrostatic attraction between the positive metal ions and the negative delocalised electrons overcomes the repulsion between the positive ions
these electrons also balance out the psotive ion's charges making the compound neutral
30
Alloys
A mixture of 2 or more metals
31
Ionic or Electrovalent bonding
Between two ions which are always one metal and one non-metal and happens when the metal donates its valence electrons to the non metal. Leaving the metal with a positive charge and non metal with a negative charge
32
Covalent Bonding
Between non-metals and non-metals where electrons are shared as no atom wnats to give up its electrons but want to gain electrons as well
33
Properties of metals
Malleability
High Density and Hardness
Good conductors due to prescene of delocalised electrons
Sonorous
Shiny/Lustrous
Very high boiling and melting point due very high attraction between metal ions
34
Sonorous
When metals strike a hard surface, they produce a sound
35
What is the sea of electrons in metals?
Outer electrons in metals separate from their atoms and become free and delocalised and form a sea of electrons. The atoms which lose these electrons become cations and the other free electrons allow for the movement of heat and electricity, making metals good conductors of both
36
What happens when a metal is hit
Layers of strong and dense lattice slide over each other but do not break unlike ionic compound lattices
37
Why is their sharing of electrons in covalent bonding
No atom wants to give their electrons, so they share to complete their octet
38
Electronegativity
Ability of atoms to gain electrons
39
Catenation
Catenation is the process of atoms of the same element linking together which is also called a chain
40
Why are the oxides of carbon and silicon different even though they are in the same group?
The carbon atom is smaller than the silicon atom
41
Lattice
a 3D arrangement of atoms, ions, or molecules in a crystalline solid.
42
Name a gaseous fossil fuel
Natural Gas
43
Name fuels obtained by distillation of petroleum
Gasoline, Kerosine, Diesel, propane
44
Name two products obtained from petroleum which are not used as fuels
Bitumen and Lubricating Oil
45
A mixture of liquid separated on an industrial scale other than petroleum
Ethanol and water
46
Which of these condust electricity during liquid state
Metallic compounds
Ionic compounds
Covalent compounds
Ionic compounds
47
Which of these condust electricity during solid state
Metallic compounds
Ionic compounds
Covalent compounds
Metallic compounds
48
Physical properties of Ionic compounds
High melting and boiling point (due to strong intermolecular forced which require a lot fo energy to break apart)
Solid at room temp
Soluble in water
Poor conductors in the solid state, but good conductors in liquid state (as in liquid state there are psotivei charged ions which can conduct, but in solid state these positive ions are fixed together in a fixed crystaline solid lattice)
49
Why are Ionic Compounds soluble in water?
Water molecules arepolar which means the oxygen attracts the positive ions in the compounds whereas the hydrogen attracts the anions. This weakens the electrostatic force in the compound and leads to dissassociation of the ion in water
50
Physical properties of Covalent compounds
Generally exist as liquid or gas in room temp
Generally low BP n MP (due to weak intermoleecular forces)
Poor conductors of electricity and heat
Not soluble in water due to absence of oppositely charged ions to attract with water's polarity
Soft in nature
51
electrical neutrality
Electrical neutrality is when something has no net electrical charge.
52
Allotropes
Matter, even if of the same element can exist in different physical states with different arrangement of atoms
53
Allotropes of carbon and their structure
DIAMOND:
- Every carbon atom is covalently bonded with 4 other carbon atoms in a tetrahedral network
- Resulting in a hard, high melting point non conductor
- Used in cutting tools and jewelry
GRAPHITE:
- Every carbon atom is covalently bonded with 3 other carbon atoms in a hexagonal structure
- Layers of hexagonal rings are stacked on top of each other
- Resulting in a slipper, soft and conducting element
- Used in pencils and Lubricants
54
Silicia covalent network shape
Each silicon atom is covalently bonded to four other oxygen atom in a tetrahedral arrangement.
55
why is silica called as a covalent network and not an allotrope
Bceause it one atom is covalently bonded with a another different type of atom (silicon with oxygen) instead of one atom being bonded with itself only
56
Why are metals good conductors of heat and electricity
loosely bound electrons roam freely throughout the metal. This is also known as the sea of electrons which carries heat energy and electricity across the metal and allows it to spread all over
57
What makes a good fuel
Energy generated
Avaliability
How can it be stored
Cost
Toxicity
How easy is it to use
58
Why do gases and liquids stay at the bottom of a fractional distillation tank?
Because they have a high boiling point and are much more dense
59
Covalent network
Giant 3D network where every atom is covalently bonded in a continuous and rigid network (lattice)
60
properties fo covalent networks
- Hard
- High MP
- Insoluble in water
- Poor conductor (except graphite)
61
macromolecules
large, complex molecules formed by linking smaller repeating units called monomers bonded together in linear or branched chains by covalent bonding
62
properties of macromolecules
Dont conduct electricity (except graphite(
Hard. however brittle
High MP and BP
63
All allotropes are bonded with what type of bonding
covalent bonding
64
crude oil
mixture
fosil fuel derived from ancient biomass found in rocks
65
what does crude oil contain
hydrocarbons and sulphers
66
order of components acheived from distillation of crude oil (first to last)
Bitumen
Lubricating Oil
Diesel
Parafin
Petrol
Liquid petroleum gas
67
what happens as you go up the fractional disstlation tower of crude oil
BP decreases
Compounds ignite more easily
Molecules contain less carbon atoms
Molecules are smaller
Molecular are less viscous (not very runny)
68
decomposition reaction endothermic or exothermic
endothermic
69
Combustion reaction endothermic or exothermic
exothermic
70
neutralisation reaction endothermic or exothermic
exothermic
71
combination reaction endothermic or exothermic
endothermic
72
All bonds in polyatomic ions and diatomic molecules are of what type?
Covalent
73
Polar Covalent Bonds
1. Electrons are shared unequally due to difference in electronegativity
2. One atom pulls the electrons more than the other, gaining it a partial negative charge and leaving the other with a partial ppositive chagre
3. Eg: H2o
74
Non polar covalent bonds
1. Electrons are shared equally
2. Happens when both atoms have same very very similar electronegativity
3. Eg: Diatomic molecules
75
All salts have what type of bonding
ionic
76
Why do covalent molecules dissolve in alcohol but not water
- Covalent compounds dissolve in alcohol because alcohol has both a non-polar part and a polar part, allowing it to interact with covalent molecular substances (as they are also majorly non polar
- However, they usually do not dissolve well in water because water is highly polar and cannot interact with non-polar covalent molecules
77
Types of covalent bonds:
Single bond
Double bond
Triple bond
Polar covalent bonds
non polar covalent bonds
78
Malleable meaning
Can be hammered into sheets without the properties changing
79
ductile meaning
can be drawn into wires without its properties changing
80
Properties of metallic bonded ions
1. Good conductors in solid and liquid state to presence of delocalized electrons (even in molten state)
2. Malleable and Ductile as layers of ions can slide over each other without breaking the structure as the sea of electrons holds everything together
3. High MP and BP
4. Lustrous
5. High density and hardness because the atoms are in a closely packed structure
81
charge on metal ion and impact on its bonding strength
The more delocalised electrons there are, the stronger the metallic bond, and a higher charge on the metal ions generally leads to a stronger bond
82
Why are metals lustrous
m electrons reflect light giving metals their shiny look
