Unit One Flashcards
How do you find relative rate
1/time
What changed the rate of reaction (ppctA)
Pressure
Particle size
Concentration
Temperature
Add a catalyst
How can activation energy be changed
Activation energy cannot be changed unless with a catalyst
What is temperature the measure of
Average kinetic energy
What happens to the number of particles with energy equal to or greater than the activation energy when the temperature is increased
Particles increase
Why does increasing temperature increase the reaction rate
Speed of particles has increased leading to more collisions
Collide with higher energy so higher chance of successful collisions
Describe Haber process
Reactants= nitrogen and hydrogen
Products = ammonia
Catalyst = iron
Describe Ostwald process
Reactants = ammonia and oxygen
Products = nitric acid
Catalyst = platinum
What is meant by the term activation energy
The lowest energy required for a reaction to occur
Adsorption (action of a catalyst)
One of the reactant molecules is adsorbed onto the surface of the catalyst it is held in place by weak bonds with the active sites on the catalyst. This weakens the reactant
Reaction (action of catalyst)
With the reactant held at the correct geometry and the chemical finds weakened, successful collisions can occur. The activation energy is lowered because I’d the reactant being adsorbed
Desorption (action of a catalyst)
The product molecules leave the active sites of the catalyst to be reused in further chemical reactions
Give an example of a catalytic converter
Reactants= carbon monoxide nitrogen oxide
Products= co2 and nitrogen
Catalyst= platinum
What is meant but the term activated complex
Unstable intermediate arrangement of atoms formed as old bonds are breaking and new bonds forming
What is meant by the term enthalpy
The potential energy involved in reactants becoming products
What must occur for a chemical reaction to take place
Particles must collide
Collisions must have sufficient energy
Reacting particles must have correct orientation
Give an example of catalyst poisoning
Iron catalyst used in Haber process will rust so it needs to be replaced or scrubbed
What are the names of the groups
Group one- alkali metals
Group two- alkali earth metals
Group seven- halogens
Group eight- Nobel gasses
What happens to the covalent radius when going across a period
From left to right electrons are being added to the same energy level and protons are being added to the nucleus. The electrons in the outer energy level are therefore attracted more strongly to the nucleus making the radius smaller
What happens to the covalent radius as you move down a group
The number of occupied electron energy levels increases. The shells are being increased so is the shielding because there are many shells. There are no values for the covalent radii of monoatomic asses as they do not form covalent bonds easily.
What is the covalent radius a measure of
Half of the distance between atoms
What is the meaning of the first ionisation energy
The amount of energy required to remove one mole of electrons from one mole of atoms In the gaseous state
What is the meaning of the second ionisation energy
The amount of energy required to remove one mole of electrons from one mole of 1+ ions in the gaseous state
Why is the second ionisation energy always higher than the first
On the second not much energy more positive 2nd and 3rd very stable, require a lot because it wants to stay stable
What happens to the ionisation energy across a period
More protons are being added through the period. So the electrostatic attraction will be increased Arabs the outer electrons more strongly so there will need to be more energy
What happens to the ionisation energy in a trend going down a group
It decreases base there is more outer shells so they will be further away from the nucleus so there is less force of attraction therefore it will be easier to remove the electron. With less energy.
What happens to the electronegativity across the period
It increases because of the increased nuclear charge
How can you increase rate of reaction
Particle size decrease increase surface area so more a collisions will occur
Concentration increase so more reactant more chance of collision
Temperature increase more energy, increased speed more chance of collision
Adding a catalyst faster reaction help geometry to collide
What is a pure covalent bond
When atoms involved in the bond have an equal share of bonding electrons
What is a polar covalent bond
When atoms with different electronegativity values join together
What type of molecules have permanent dipole permanent dipole interaction
Molecules that are polar
What is a highly electronegative element
Nitrogen,oxygen or fluorine
What happens as the relative atomic mass in the halogen increases
Boiling point increases
What is the definition of electronegativity
A measure of the attraction of an element for bonding electrons
Why is the third ionisation energy higher than the second
Successive ionisation energies increase as the atoms become more positive
Where does the melting and boiling point values peak
At carbon and silicon
What happens as you go down group 7
Increase in mp so
An increase in the force of attraction
What do melting and boiling points show
Periodic properties
This means that they vary in a regular way or pattern depending on their position in the periodic table
What do the melting points and boiling points depend on
The strength of forces which exist between the particles which make up a substance
What is the definition of density
The mass per unit volume
Where does density values peak
at boron(a group three element)in group two and aluminium a group three element in period three
What happens to density going down a group
It increases
What is the definition of London dispersion force
They are formed as a result of electrostatic attraction between temporary dipoles and induced dipoles Inducrd by movement of electrons in atoms and molecules
