chemistry year 1

First ionisation energy definition

The energy required to remove 1 electron from 1 mol of gaseous atoms to form 1 mol of gaseous ions in their gaseous state.

Factors affecting first ionisation energy

Shielding, nuclear charge, atomic radius

What happens with successive ionisation energies

Successive ionisation energies increase due to greater number of protons per electron and decreased electron shielding as electrons are removed.

Where is the large jump in successive ionisation energies

When the electron being removed is from a new inner shell.

Trend in first ionisation energy down a group

First ionisation energy decreases due to increased atomic radius and greater electron shielding, making it easier to remove an outer electron.

Trend of first ionisation energy across a period

First ionisation energy increases across a period due to increasing nuclear charge, which attracts electrons more strongly and decreases atomic radius.

Why is removing an electron from a group 3 element easier than group 2

Group 3 elements’ outer electron is on the p-orbital as opposed to s-orbital, which is higher in energy and further from the nucleus, making it easier to remove.

Why is removing an electron from a group 6 element easier than group 5

Group 6 has 2 electrons in the p orbital where the electron is being removed, and due to the electrostatic repulsion between them this makes an electron easier to removecompared to group 5, where there is only one electron in the p orbital.

Word to use instead of “charge carrier”

Mobile electrons/ions

Elements that form giant covalent lattices

Silicon, carbon and boron

Why does sulfur have a higher melting point than phosphorus

Because sulfur forms S8 and phophorus forms P4, so S8 has more electrons so larger london forces

Why do giant covalent structures have higher melting points than metallic structures

Giant covalent structures have 4 covalent bonds per atom, requiring more energy to break compared to the metallic bonds in metallic structures.

Electronegativity definition

The ability for atoms to attract the bonding electrons in a covalent bonds

What is the Pauling scale

The measure of electronegativity

What does electronegativity difference dictate

Bond type

How do simple molecular substances interact in polar solvents

Does not dissolves in water

How to represent a hydrogen bond on a diagram

Dashed line between H nucleus and lone pair

What can increase london forces?

The number of electrons in the molecule

If all of the atoms are in a longer and thin structure

Order of intermolecular forces in strength

London forces < permanent dipole dipole < hydrogen bonding

Are non polar substances soluble in polar solvents

No

Is a non polar substance soluble in a non polar solvent

Yes (e.g. hexane)

Why is the solubility of polar molecules are hard to predict?

Depends on the strength of the dipole

How do london forces come about?

Random movement of electrons produces a changing dipole which will induce a dipole on the neighbouring molecules. London forces are the attraction due to these instantaneous dipole.

How do permanent dipole dipole forces arise?

In a polar molecule, the permanent dipoles attract each other so the molecules form an arrangement with positive and negative charges adjacent

What are the anomalous properties of water due to hydrogen bonds

Higher B.P./M.P, high viscosity and surface tension, liquid water is more dense than ice

Why is water less dense than ice

The hydrogen bonds form a open lattice structure which is less dense than liquid structure

What elements form hydrogen bonds

H/N/O/F

Hydrogen bond definition

A strong dipole dipole interaction between a positive hydrogen nucleus and a lone pair of electrons

Symbol for dipoles

What is a polar molecule

A non symmetrical molecule with polar bonds so there is an overall dipole

Factors that affect electronegativity

Nuclear charge, atomic radius and shielding

How many hydrogen bonds does a water molecules form

2 hydrogen bonds

Why are non polar substances insoluble in polar solvents

The intermolecular forces are weaker in the substance so there will not be enough interaction between solvent and solute to dissolve

Why is a non polar substance soluble in a non polar solvent

Because the intermolecular forces interact and weaken in the simple molecular lattice, causing the solvent to move apart and allow the substance to dissolve

How does nuclear charge affect electronegativity

The more protons the stronger the attraction between the nucleus and the bonding pair

How does atomic radius affect electronegativity

Closer to the nucleus means stronger attraction between the nucleus and bonding pair

How does shielding affect electronegativity

Less shells of electrons between the nexulus and shared pair causes stronger attraction

How can you find atomic mass from mass spectrometry

The furthest right significant peak at mass spectrometry is the M+ peak, which represents the atomic mass as m/z when z = 1 is equal to m

What is the M+1 peak

A tiny peak 1 above the M+ peak, representing the fragment ions with an extra neutron on the carbon atom

How does a mass spectrometer work

An electron beam knocks 1 electron off each molecule, accelerated through an electromagnetic field, then the amount that the ion was deflected and where it is detected indicates the m/z ratio

What are fragment ion peaks used for

we can use fragments to figure out the overall structure of the molecule like where alkyl branches are

How does an infrared spectrometer work

We fire infrared radiation at the molecules and different bonds absorb the radiation and we can detect which wavenumbers of waves are absorbed which tells us the functional groups present in the moleucle

What ways can bonds vibrate

A bond can stretch or bend

How do greenhouse gases cause the greenhouse effect

The radiation emitted by earth is absorbed by the bonds in greenhouse gases causes the earth to warm by reabsorbing the reemitted radiation

What is the fingerprint region

A section of an infrared spectrum which, using computer analysis, can identify the specific molecule

What is infrared spectroscopy used for

We can analyse air samples to see which pollutants are present

In breathalysers, so it can be detected if there is a certain concentration of alcohol in the breath

What does a receiver look like

What does a screw tap adaptor look like

What does a still head look like

What are anti bumping granules for

To prevent large bubbles from forming and shaking the apparatus

How to find out which layer in a solution is organic and aqueous

If you add water the aqueous layer will increase in size

What will cause impurities in organic layers

Reactions with acids

How to remove acid impurities from the organic layer

Add sodium carbonate to a separating funnel, invert and open the tap to let the carbon dioxide out

Drying agents

Anhydrous salts

How to dry a solution

Add a drying agent and swirl the flask then leave a stopper on. The liquid will be clear if it is dry

Alkane to haloalkane conditions/reagants

halogen and UV light

Alkene to haloalkane conditions/reagants

hydrogen halide (or halogen)

Alkene to alkane conditions/reagants

Hydrogen with nickel catalyst at 423K

Alkene to alcohol conditions/reagants

Steam with a phosphoric acid catalyst

Alcohol to alkene conditions/reagents

Concentrated phosphoric acid to undergo elimination

Alcohol to haloalkane conditions/reagents

Concentrated sulfuric acid and sodium halide

Haloalkane to alcohol conditions/reagents

Sodium hydroxide under reflux

Alcohol to ketone

Heating under reflux with acidified potassium dichromate with a secondary alcohol

Alcohol to carboxylic acid

Heating under reflux with acidified potassium dichromate with a primary alcohol

Alcohol to aldehyde

Distillation with acidified potassium dichromate of a primary alcohol

What is the prefix for OH

hydroxyl

Why do alcohols have higher melting points than alkanes

Because there is a dipole on the OH causing hydrogen bonds between the alcohol, which are stronger than the london forces

Alcohols solubility in water

Very soluble because the alcohol forms hydrogen bonds with the water, solubility decreases as chain length increases

How is a primary, secondary and tertiary alcohol defined

How many carbons are attached to the carbon with the OH

What does the oxidation of primary alcohols form

Aldehydes and carboxylic acids

Conditions for alcohol forming aldehyde

Gentle heating under distillation with acidified potassium dichromate with an oxidising agent

Conditions for alcohol to carboxylic acid

Heated under reflux with acidified potassium dichromate and oxidising agent

Conditions for alcohol to ketone

Heated under reflux with acidified potassium dichromate and oxidisng agent

What is a dehydration reaction

When water is removed from an alcohol to make an alkene

Conditions for dehydration

Acid catalyst and heated under reflux

What reactants are required to make a haloalkane from an alcohol

Sulfuric acid, alcohol, and sodium halide (hydrogen halide is formed with sufuric acid and sodium halide)

What mechanism do haloalkanes to alcohols undergo

Nucleophilic substitution

What is hydrolysis

The breaking of a bond in a molecule in a solution with hydroxide or water

Name 3 main nucleophiles

Water, ammonia and OH- ion

What reagents and conditions are there for the hydrolysis of a haloalkane

NaOH and heated under reflux

How does carbon-halogen bond strength vary down the group

The average bond enthalpy decreases

How does bond enthalpy of carbon-halogen bond affect the rate of hydrolysis

The larger the bond enthalpy of the carbon-halogen bond, the slower the reaction rate

How to measure rate of hydrolysis

Add aqueous silver nitrate, so precipitate is formed as halide is released into solution. This has to be done with ethanol and water so the haloalkane doesn’t form a separate layer

What is a cfc

Chlorofluorocarbon

Why is depletion of the ozone layer dangerous

Because more UVB radiation will hit humans which can cause genetic damage and skin cancer

Is hydrolysis quicker in tertiary or primary haloalkanes and why

Tertiary because it uses a two step mechanism instead of a one step mechanism like primary

Where does the nucleophile attack in hydrolysis

The opposite side of the carbon atom to the functional group

How does a nitrogen oxide radical react in the ozone layer (equations)

Acts as a catalyst

How does a chlorine radical (as a catalyst) react in the atmosphere

How do OH radicals react in the ozone layer

What is needed for a collision to be successful

Correct orientation and particles must have activation energy

Activation energy definition

The minimum energy required for a reaction to take place

How does rate of reaction change during a reaction

Starts at its quickest, and the rate gradually slows down

What factors can alter rate of reaction

Concentration/pressure

Temperate

Catalyst

Surface area

How does conc/pressure effect ror

Particles are closer together so particle collisions are more frequent collisions so more effective collisions

How to measure ror experimentally (2 ways)

Measuring the decrease in mass using a balance during a reaction or measuring the volume of gas produced

Catalyst definition

When a substance isn’t used up in a reaction and decreases the activation energy

Homogeneous catalyst

Catalyst thats in the same physical state as the reactants

Heterogeneous catalyst

Catalyst thats a different physical state as the reactants (usually solids with gaseous reactants)