Unit 1 Flashcards
How to calculate the average rate
Time interval
What is Collision Theory?
The idea of reactions taking place by the reactant particle colliding with eachother
Collision Theory states that substances may only react with eachother if:
1- Their particles collide with eachother
2- These collisions have sufficient energy
3- The particles collide with the correct geometry
What is meant by the term Heterogeneous?
The catalyst is in a different state from the reactant
What is meant by the term Homogeneous?
The catalyst is in the same state as the reactant
What are enzymes?
Biological catalysts.
They are complex protein molecules which speed up specific chemical changes by homogeneous catalysis.
How do you calculate the relative rate?
t
How do you calculate the enthalpy change (∆H)?
products - reactants
What does Ea stand for?
Activation energy
Where is the activated complex situated?
The top (curve) of a graph
What happens in an exothermic reaction?
∆H value has a negative sign/value
Energy is lost
What happens in an endothermic reaction?
∆H value has a positive sign/value
energy is taken in
What does a catalyst provide in potential energy diagrams?
a different reaction pathway to the product
Features of a metallic lattice:
- high density indicating closely packed together
- the outer electrons on a metal atom are “delocalised”
What kind of melting and boiling point do metals have?
high
What is said about metallic bonding?
said to be very strong
What are the 2 types of metal (shapes)?
Malleable and ductile
What are Malleable metals?
when metals can be bent and hammered into different shapes
What are Ductile metals?
Can be pulled and squeezed to produces wires
What is said about boiling points of alkali metals? (going down group 1)
Going down group 1, the boiling points decrease. This indicates the strength of the metallic bonding is getting weaker.
The outermost electron on each atom gets further away from the positive nucleus. This increasing distance reduces the strength of the metallic bonding.
What is said about boiling points of metals? (across group 3)
Boiling point increases; indicating boiling point is getting stronger
Going across group 3; the number of outermost electrons on each atom increases.
The more outer electrons on a metal atom, the stronger the metallic bonding.
What are monatomic elements?
Group 0 - noble gases
Don’t form bonds with other elements
What are London Dispersion forces? and how are they formed?
Very weak forces
They are formed by the attraction between positive and negative charges (electrostatic attraction)
What is another name for London Dispersion forces?
Temporary dipole - Temporary dipole
What happens when a temporary dipole comes close to a neutral atom? and what does it from?
It affects the distribution of electrons, formation of an induced temporary dipole.
What are diatomic elements held together by?
Strong covalent bonds
What is a covalent bond?
The electrostatic attraction between a shared pair of electrons and the positively charged nuclei of the 2 atoms, which are sharing the electrons.
What is Atomic size?
the strength of some bonding is influenced by the size of the atoms involved.