Unit 1 flashcards

Flashcard maker : Sonia Kelly
What equation do you use to work out the rate of a reaction if it has a distinct end?

Rate = 1/time

What two things are needed for a reaction to take place?

energy above the activation energy 

-collision of particles at the correct angle or orientation

What is Activation Energy?

the minimum amount of energy required for a reaction

What is the activated complex?

the unstable intermediate between reactants and products containing partial bonds

How do you calculate the enthalpy change of a reaction?


(enthalpy of products – enthalpy of reactants)

What do catalysts do?

Catalysts lower the activation energy increasing the number of particles able to react

How do Heterogeneous catalysts work?

They work by adsorbing reactants onto active sites which weakens their bonds.

How does poisoning of catalysts occur?

Poisoning occurs when chemicals are absorbed onto active sites stopping them working

How can enzymes be denatured?

 Enzymes can be denatured if the pH, temperature or alcohol content is too extreme

Define each component /H=cm/T


?H is enthalpy change

c is 4.18 Kj/mol

m is number of kilograms (litres) of water

?T is the temperature change

What step comes after working out the energy change for a certain mass of compound reacting?

work out how much 1 mole would produce

Why does atomic size increase going down a group?

there is an extra energy level moving the electrons further from the nucleus thus increasing the size

Why does ionisation energy increase across a period?

It increases across a period as the electrons are closer to the nucleus therefore harder to remove

Why does ionisation energy decrease down a group?

It decreases down a group as the electrons are further from the nucleus and shielded from its pull by the inner electrons

Why is there a large jump between the first and second ionisation energies?

There is a large jump between the first and second ionisation energies for group 1 metals as you are removing an electron from an energy level closer to the nucleus

Why does electronegativity increase going across a period?

It increases across a period as the nuclear charge increases pulling the electrons closer

Why does electronegativity decrease down a group?

It decreases down a group as the pull of the nucleus is being shielded by the inner electrons

What do atoms with equal electronegativities form?

Pure covalent bonds

What do atoms with different electronegativities form?

POLAR covalent bonds

What are the symbols for the atoms with the biggest and lowest electronegativities?

The atoms with the biggest electronegativities have a ?-charge and those with the lowest value have a ?+ charge.

Describe metallic bonding

Metallic bonds have positive cores surrounded by delocalised electrons enabling the metals to conduct.

Where is metallic bonding found and is it strong?

This force of attraction is very strong and exists in metal elements.

Describe Ionic bonding

Ionic bonds are an electrostatic force of attraction between oppositely charged ions.

Describe ionic bonding’s melting points ; structure

They have high melting points and have a crystal lattice structure that must be broken before the ions are free to move and conduct electricity.

Are ionic compounds soluble?

Ionic compounds are soluble in polar solvents like water

Describe the strength of covalent bonds

Covalent bonds are very strong and difficult to break

Describe covalent Network bonding

Covalent network substances have massive structures with millions of bonds which have to be broken to change their state

What are covalent molecular’s at room temp and what is broken to change their state?

•Covalent molecular substances are usually liquid or gas at room temperature.



•It is weak intermolecular forces that are broken when their state is changed

How are dipole-dipole attractions caused?

Dipole –Dipole attractions are caused by molecules that have a permanent dipole


They are stronger than Van der Waals.

Describe Van Der Waals Strength.

They are the weakest intermolecular force

What will one mole of a substance contain?

6.02×1023 formula units

What will one mole of a monatomic element contain?

6.02×1023 atoms

What will one mole of a diatomic and covalent molecular substance contain?

6.02×1023 molecules



What will one mole of Ionic compounds contain?

6.02×1023 formula units

What happens to the molar volume of all gases at constant temperature and pressure?

Stays the same

How do we work out volume of gases from a balances equation?

We can use simple ratios to work out the volumes of gases from a balanced equation

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