Chemistry - Periodic Table and Energy

?
What is periodicity?
A repeating trend in properties of the elements across each period of the periodic table.
1 of 78
What is first ionisation energy?
The energy required to remove one electron from each atoms in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.
2 of 78
How does atomic radius affect ionisation energy?
The greater the radius, the less the nuclear attraction, so the ionisation energy decreases.
3 of 78
How does nuclear charge affect ionisation energy?
The more protons in the nucleus, the greater the nuclear attraction between the nucleus and the outer electrons, so the greater the ionisation energy.
4 of 78
How does electron shielding affect ionisation energy?
More electron shells causes more electron shielding, which causes a lower ionisation energy.
5 of 78
What does a large increase in ionisation energy mean on an ionisation energy graph?
It suggests that the electron must be removed from a different shell, closer to the nucleus and with less shielding.
6 of 78
Why is the first IE of oxygen less than that of nitrogen?
The electrons in the outer orbitals in nitrogen are unpaired, whereas there is one paired electron orbital in oxygen. The paired electrons repel each other, making it easier to remove one from an atom.
7 of 78
What is metallic bonding?
The electrostatic attraction between positive metal ions and delocalised electrons. The cations are fired in position, maintaining the metal's shape, but the electrons are mobile so are able to move.
8 of 78
Why do metals have high melting and boiling points?
High temperatures are required to provide the large amount of energy needed to overcome the strong metallic bonds.
9 of 78
What is the solubility of metals?
Metals do not dissolve as any interactions between the polar solvent and the charges in the metallic lattice would lead to a reaction, rather than dissolving.
10 of 78
Why do giant covalent lattices have high melting and boiling points?
The covalent bonds are strong so high temperatures are needed to provide the energy to break the bonds.
11 of 78
Why are giant covalent lattices insoluble in almost all solvents?
The covalent bonds holding the atoms together are far too strong to be broken by solvent interaction.
12 of 78
What are reducing agents?
Species that will reduce another species.
13 of 78
Are group 2 elements oxidising or reducing agents?
Reducing agents as they reduce other species.
14 of 78
How does the reactivity of group 2 change down the group?
Down the group, there are more electron shells, so the nuclear attraction increases as the atomic radius increases and shielding increases. Therefore, the IE decreases, so the reactivity increases as electrons are lost more easily.
15 of 78
How does the solubility of group 2 hydroxides change down the group?
The solubility increases as the OH- concentration increases. This leads to an increase in pH and alkalinity.
16 of 78
What are group 2 elements used for?
Hydroxides are used in agriculture to neutralise soil. Bases are used in medicine to treat indigestion.
17 of 78
How does the boiling point of halogens increase down the group?
There are more electrons, so there are stronger London forces. This means more energy is required to break the IM forces, so the boiling point increases.
18 of 78
Are halogens oxidising or reducing agents?
Oxidising as they oxidise another species.
19 of 78
What colour are halogen solutions in water?
Chlorine - Pale Green, Bromine - Orange, Iodine - Brown
20 of 78
What colour are halogen solutions in cyclohexane?
Chlorine- Pale Green, Bromine - Orange, Iodine - Violet
21 of 78
How does reactivity of halogens change down the group?
The atomic radius increases. There are more inner shells so shielding increases, there is less nuclear attraction so the reactivity decreases as it is harder to capture an electron from another species.
22 of 78
How is bleach formed?
During the reaction of cold dilute aqueous sodium hydroxide with chlorine.
23 of 78
What are the benefits and risks of chlorine use?
Chlorine is extremely toxic. Chlorine in water can react with organic hydrocarbons in water, which can form chlorinated hydrocarbons, which are suspected of causing cancer. However, chlorine kills bacteria in water.
24 of 78
What is the test for halide ions?
Add aqueous sliver nitrate and a precipitate will form (white for chlorine, cream for bromine and yellow for iodine)
25 of 78
What is the test for carbonate?
React dilute nitric acid with the sample. Bubble the produced gas through lime water and the CO2 will react to form a white precipitate, turning the limewater milky.
26 of 78
What is test for sulphate?
Most sulphates are soluble in water but barium sulphate is very insoluble. Add barium ions using aqueous barium chloride/nitrate and a white precipitate of barium sulphate will form.
27 of 78
What is the sequence of anion tests?
Carbonate, sulphate and halide. Sulphate test is done after carbonate as a carbonate will also produce a white precipitate from barium chloride. Silver carbonate and silver sulphate are also insoluble, so will form precipitates (incorrect result)
28 of 78
What is the test for ammonium ions?
Add aqueous sodium hydroxide to solution. Ammonia gas will be produced (no gas bulbs as ammonia is insoluble in water). Warm the mixture and the gas is released, which can be tested with moist indicator paper (alkaline so will turn blue)
29 of 78
What is enthalpy?
A measure of the heat energy in a chemical system.
30 of 78
What happens in an exothermic reaction?
The energy is transferred from the system to the surroundings. Change(H) is negative.
31 of 78
What happens in an endothermic reaction?
The energy is transferred from the surroundings to the system. Change(H) is positive.
32 of 78
What is the activation energy?
The minimum energy required for a reaction to take place.
33 of 78
What are the standard conditions?
Standard pressure = 100kPa, Standard temperature = 298K, Standard concentration = 1moldm^-3
34 of 78
What is the standard state?
The physical state of a substance under standard conditions.
35 of 78
What is the standard enthalpy change of reaction?
The enthalpy change alongside a reaction in the molar quantities shown in a chemical equation under standard conditions, with all reactants and products in their standard states.
36 of 78
What is the standard enthalpy change of formation?
The enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions, with all reactants and product in the standard state.
37 of 78
Why is the enthalpy change of formation for elements zero?
There is no change in the enthalpy.
38 of 78
What is the standard energy change of combustion?
The enthalpy change when one mole of a substance reacts completely with oxygen, under standard conditions, with all reactants and products in their standard states.
39 of 78
What is the enthalpy change of neutralisation?
The energy change that accompanies the reaction of an acid by a base to form one mole of H2O(l), under standard conditions, with all reactants and products in their standard states.
40 of 78
Why is the enthalpy change of neutralisation always the same?
It involves the reaction of H+ with OH- to form one mole of H2O(l), which will happen in all neutralisation reactions.
41 of 78
What is the equation for calculating the energy change of a reaction?
Q=mcΔT
42 of 78
What does the m represent in the Q=mcΔT equation?
The mass of the surroundings (e.g. water)
43 of 78
How accurate is the ΔH(combustion) value from experiment?
There could be heat loss to surroundings other than water. The combustion of the fuel could be incomplete. There could be evaporation of the fuel or water. There could be non-standard conditions (all give a less exothermic value)
44 of 78
What is average bond enthalpy?
The energy required to break one mole of a specified type of bond in a gaseous molecule.
45 of 78
Why are average bond enthalpies always positive values?
Energy is required to break the bonds so the bond enthalpies are always endothermic.
46 of 78
What are the limitations of average bond enthalpy?
They are calculated from the actual bond enthalpies in different environments (bond enthalpies take on different values depending on the chemical environment).
47 of 78
Is bond breaking exothermic or endothermic?
Endothermic as energy id required to break bonds.
48 of 78
Is bond making exothermic or endothermic?
Exothermic as energy is released to form bonds.
49 of 78
What type of reaction is it if the products have less energy that the reactants?
Exothermic as more energy is released in making bonds than the amount put in to break the bonds.
50 of 78
What type of reaction is it if the reactants have less energy than the products?
Endothermic as the energy required to break the bonds is greater than the amount released when making bonds.
51 of 78
What is the equation for the enthalpy change of reaction?
Σ(bond enthalpies in reactants) - Σ(bond enthalpies in products)
52 of 78
What is Hess' Law?
If a reaction can take places by two routes, and the starting and finishing conditions are the same, the total enthalpy change is the same for each route.
53 of 78
What does Hess' Law allow?
It allows for the enthalpy change of reactions to be determined indirectly.
54 of 78
What is the equation for ΔH(reaction) using enthalpy changes of formation?
ΣΔHf(products) - ΣΔHf(reactants)
55 of 78
What is the equation for ΔH(reaction) using enthalpy changes of combustion?
ΣΔHc(reactants) - ΣΔHc(products)
56 of 78
What is meant by the rate of a chemical reaction?
A measure of how fast a reactant is being used up or how fast a product is being formed. (change in conc)/(time)
57 of 78
Why is the rate of reaction fastest at the start of the reaction?
Each reactant is at its highest concentration.
58 of 78
Why does the rate of reaction slow down as the reaction proceeds?
The reactants are being used up and their concentrations decrease.
59 of 78
When does the rate of reaction become zero?
When one of the reactants has been completely used up, so the concentrations stop changing.
60 of 78
What conditions must a collision meet in order for it to be effective?
The particles must collide with the correct orientation and the particles must have sufficient energy to overcome the activation energy barrier.
61 of 78
Why does increasing the concentration/pressure increase the rate of reaction?
There are more particles per unit volume, so they are closer together, leading to more frequent collisions and more effective collisions in a given time.
62 of 78
How can the progress of a reaction be followed?
By monitoring the removal of a reactant or the formation of a product.
63 of 78
How can you determine the rate of a reaction that produces a gas?
Monitor the volume of gas produced at regular time intervals using gas collection or monitor the loss of mass of reactants using a balance.
64 of 78
What is a catalyst?
A substance that changes the rate of a chemical reaction without undergoing any permanent change itself.
65 of 78
What is a homogeneous catalyst?
It has the same physical state as the reactants and reacts with the reactants to form an intermediate. The intermediate then breaks down to give the products and regenerates the catalyst.
66 of 78
What is a heterogeneous catalyst?
It has a different physical state from the reactants. Reactant molecules are absorbed onto the surface of the catalyst, where the reaction takes place. After reaction, the produce molecules leave the surface of the catalyst by desorption.
67 of 78
What are the main three features of a Boltzmann distribution?
No molecules have zero energy so the curve starts at the origin. The area under the curve is equal to the total number of molecules. There is no maximum energy so the curve does not meet the x-axis at a high energy.
68 of 78
What is a reversible reaction?
A reaction that can take place in both forward and reverse directions.
69 of 78
What are the features of an equilibrium system?
The rate of the forward reaction is equal to the rate of the reverse reaction and the concentrations of reactants and products do not change.
70 of 78
What is a closed system?
A system that is isolated from its surroundings.
71 of 78
What is le Chatelier's principle?
When a system in equilibrium is subjected to a external change the system readjusts itself to minimise the effect of that change.
72 of 78
What does the position of equilibrium indicate?
The extent of the reaction.
73 of 78
How does increasing the temperature affect the equilibrium position?
Increasing the temperature shifts the EP in the endothermic direction, so the products make from the endothermic reaction will have a higher yield.
74 of 78
How does increasing the pressure affect the equilibrium position?
The reaction that produces the fewest gaseous molecules will be favoured, so the EP will shift in that direction.
75 of 78
How does a catalyst affect the equilibrium position?
It does not affect the EP. It only speeds up both reactions by the same amount. A catalyst will increase the rate at which equilibrium is established.
76 of 78
What is an equilibrium constant?
A measure of the position of equilibrium. The magnitude indicates whither there are more reactants or products in the equilibrium system.
77 of 78
What does the value of the equilibrium constant mean?
If it is 1, the EP is halfway between reactants and products. If it is less than 1, the EP is towards the reactants. If it is more than 1, the EP is towards the products.
78 of 78

Other cards in this set

Card 2

Front

What is first ionisation energy?

Back

The energy required to remove one electron from each atoms in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions.

Card 3

Front

How does atomic radius affect ionisation energy?

Back

Preview of the front of card 3

Card 4

Front

How does nuclear charge affect ionisation energy?

Back

Preview of the front of card 4

Card 5

Front

How does electron shielding affect ionisation energy?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all The Periodic Table resources »