Unit 1 Flashcards
Ionisation energy
Energy required to pull one mole of electrons away from one mole of gaseous atoms
Electronegativity
Atom which has a strong attraction for bonding is said to be highly electronegative
Collision theory says that a chemical reaction takes place when
Molecules have sufficient energy known as the Ea
Molecules collide with the correct geometry
The number of collisions is affected by
Concentration
Particle size
Pressure
Activation energy is affected by
Temperature
How does increasing the temperature affect the reaction rate
More particles will have the minimum energy and therefore more reactions will take place
What is activation energy
Ea
Sufficient energy for a reaction to take place
Catalysts increase reaction rate by
Allowing the reaction to take place via an alternative route that has a lower activation energy
Two types of catalyst
Heterogeneous- different state from substrate
Homogeneous- same state
How to measure relative rate
RR=1/time taken for reaction
Enthalpy
Measure of chemical potential energy contained in a substance
Change in enthalpy =
Hp-Hr
In an exothermic reaction the products have_____ energy than the reactants
Less
Therefore always negative
In an endothermic reaction the products have_____ energy than the reactants
More
Therefore always positive
Intermolecular bonding
Van der waals and between different molecules eg water and water
Intramolecular bonding
Bonding within a molecule eg hydrogen and oxygen in water
Non polar
Pure equal forces of attraction
Polar
Slightly negative or slightly positive
Ionic
Very electronegative atom takes an electron away from the other, forming an ion
Properties of ionic
High melting point
Conducts electricity when molten or solution
Always solid room temp
What to remember about solubility of substances
Like dissolves in like
Covalent molecular properties
Any state at room temp
Lower melting point
Never conducts
Covalent network substances
Carbon
Silicon
Boron
London dispersion forces
Weak electrostatic attractions due to a temporary dipole forming
Can be found in everything
Only force of attraction for non polar
As number of electrons increase, strength of LDF increases
Dipole
Molecules in which an unequal distribution results in one side being slightly charged
Permanent dipole-Permanent Dipole
Electrostatic attractions between permanent dipoles in molecules
Only for polar
Strong
What substances have PDPPDP
Aldehydes and ketones
Hydrogen bonding
Occurs when hydrogen is bonded next to a highly electronegative element such as oxygen, nitrogen or fluorine
Occurs in water
very strong
