CHEM Flashcards
Take in energy? (what reaction type)
Endothermic
Gives out energy (what reaction type)
exothermic
Increase in temp in surrounding/environment ((what reaction type)
exothermic
Decrease in temp in surrounding/environment (what reaction type)
endothermic
Heat is transferred from an object at high temp to a lower temp object until both of them are ……
equal
Bond breaking what type of reaction
Endothermic - absorbs energy
Bond forming what reaction type
exothermic - releases energy
Enthalpy
Change in Temp
Enthalpy and change in enthalpy symbol
H
ΔH
Bond Enthalpy
This is the energy required to break one mole of a specific bond type
If heat is absorbed (endothermic) ΔH is
positive
If heat is released (exothermic) ΔH is
negative
Entropy
Measurement of a system’s disorder or randomness
Entropy is most and least in
Most in gaseous
Least in solids
What all is required for a thing to burn
Heat, oxygen and fuel (substance containing carbon)
In which energy diagram is the product energy, less than the reactant energy
Exothermic (energy released is calculated by reactant energy - product energy
In which energy diagram is the product energy, more than the reactant energy
Endothermic (Energy absorbed is calculated by product energy - reactant energy)
Products of any combustion reaction
Water vapour and Carbon dioxide
Incomplete combustion
When there is insufficient oxygen in a combustion reaction and instead of carbon dioxide, carbon monoxide is formed
Ignition temp
Min temp required for something to catch fire
Bonding
The force of attraction between atoms so that they can be joined chemically
Why is bonding done
For an atom to become stable and make the outermost shell full
octet rule
the eight-electron arrangement in the outer electron shell of a noble-gas atom
Ions
Particles which carry a +ve or -ve charge
In bonding, what is used?
valence electrons
Metals valency
metals only have 1,2 or 3 valence electrons which they lose, making them cations
Types of bonding
Metallic, Ionic, Covalent
Metallic bonding
Between two metals or alloys
Alloys
A mixture of 2 or more metals
Ionic or Electrovalent bonding
Between two ions which are always one metal and one non-metal
Covalent Bonding
Between non-metals and non-metals where electrons are shared
Properties of metals
Malleability
Durability
Good heat conductors
Good conductors of electricity
Sonorous
Shiny/Lustrous
Very high boiling and melting point
Sonorous
When metals strike a hard surface, they produce a sound
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
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
Why is their sharing of electrons in covalent bonding
No atom wants to give their electrons, so they share to complete their octet
Electronegativity
Ability of atoms to gain electrons
Max amount of bonds carbon can form with itself
4
Catenation
Catenation is the process of atoms of the same element linking together which is also called a chain
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
Which atom is found in millions of compounds
Carbon
Lattice
a 3D arrangement of atoms, ions, or molecules in a crystalline solid.
Name a gaseous fossil fuel
Natural Gas
Name fuels obtained by distillation of petroleum
Gasoline, Kerosine, Diesel, propane
Name two products obtained from petroleum which are not used as fuels
Bitumen and Lubricating Oil
A mixture of liquid separate on an industrial scale other than petroleum
Ethanol and water
If the oxidation number is positive, then electrons are
lost
Which of these condust electricity during liquid state
Metallic compounds
Ionic compounds
Covalent compounds
Ionic compounds
Which of these condust electricity during solid state
Metallic compounds
Ionic compounds
Covalent compounds
Metallic compounds
Physical properties of Ionic compounds
High melting and boiling point
Solid at room temp
Poor conductors in the solid state, but good conductors in liquid state
Physical properties of Covalent compounds
The state depends on compounds used
Boiling and melting points vary depending on the strength of covalent bonds and molecular weight
Poor conductors of electricity
Good conductors of heat - depending on the compound
electrical neutrality
Electrical neutrality is when something has no net electrical charge.
Allotropes
Matter, even if of the same element can exist in different physical states
Allotropes of carbon and their structure
Graphite - Hexagonal structure with each atom connected with 4 others
Diamond - Tetrahedron shape with each atom connected with 4 others
Silicia Alltrope shape
Each silicon atom is covalently bonded to four other oxygen atom in a tetrahedral arrangement.
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
Which of the following is maleable and ductile:
Ionic bonds, Colvalent bonds or Metallic bonds
Metallic
What makes a good fuel
Energy generated
Avaliability
How can it be stored
Cost
Toxicity
How easy is it to use
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
Covalent network
a chemical compound where atoms are bonded by covalent bonds in a continuous network
All allotropes are bonded with
covalent bonding
