Topic 9 Periodic Table: Periodicity

The following are high-level thinking skills (KBAT) questions designed based on the learning outcomes provided:

9.0 Periodicity

9.1 Physical properties of elements of Period 2 and Period 3.

1. Arrange elements in period 2 and 3 according to its ∆H of vaporisation. How would we determine the relationship between ∆H of vaporisation with the elements in Period 2 and 3 using its structure and bonding properties?

2. Why is enthalpy change of vaporization important?

3. With several specific examples, how would we relate between elements in period 2/ period 3, and electrical conductivity?

4. How does ionization energy relate to reactivity?

5. How does ionisation energy affect the role of period 2/ period 3 elements act as oxidising and reducing agents?

6. Why does Lithium act as a strong reducing agent even if it has low Ionisation Enthalpy ?

7. Explain the trend in ionisation energies across Period 2 and Period 3 and down a group?

8. With several specific examples, how can we predict the electronic configuration and position of unknown elements in the Periodic Table from successive values of ionisation energies?

9.2 Reactions of Period 3 elements with oxygen and water.

9.3 Acidic and basic properties of oxides and hydrolysis of oxides.

1. With give several of specific examples, how the oxides elements in period 2 and period 3 can be classified based on their characteristics/ properties into whether it neutral, amphoteric, basic, acidic?

Homework

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9 Periodic Table: Periodicity

9.1 Physical properties of elements of Period 2 and Period 3

Candidates should be able to:

(a) interpret and explain the trend and gradation of atomic radius, melting point, boiling point, enthalpy change of vaporisation and electrical conductivity in terms of structure and bonding;

(b) explain the factors influencing ionisation energies;

(c) explain the trend in ionisation energies across Period 2 and Period 3 and down a group;

(d) predict the electronic configuration and position of unknown elements in the Periodic Table from successive values of ionisation energies.

 

9.2 Reactions of Period 3 elements with oxygen and water

Candidates should be able to:

(a) describe the reactions of Period 3 elements with oxygen and water;

(b) interpret the ability of elements to act as oxidising and reducing agents.

 

9.3 Acidic and basic properties of oxides and hydrolysis of oxides

Candidates should be able to:

(a) explain the acidic and basic properties of the oxides of Period 3 elements;

(b) describe the reactions of the oxides of Period 3 elements with water;

(c) describe the classification of the oxides of Period 3 elements as basic, amphoteric or acidic based on their reactions with water, acid and alkali;

(d) describe the use of sulphur dioxide in food preservation.

9 Periodic Table: Periodicity

9.1 Physical properties of elements of Period 2 and Period 3

Candidates should be able to:

(a) interpret and explain the trend and gradation of atomic radius, melting point, boiling point, enthalpy change of vaporisation and electrical conductivity in terms of structure and bonding;

Trend and gradation in terms of structure and bonding:

atomic radius,

melting point,

boiling point,

enthalpy change of vaporisation and

 

electrical conductivity.

oxides

(b) explain the factors influencing ionisation energies;

(c) explain the trend in ionisation energies across Period 2 and Period 3 and down a group;

(d) predict the electronic configuration and position of unknown elements in the Periodic Table from successive values of ionisation energies.

9.2 Reactions of Period 3 elements with oxygen and water

Candidates should be able to:

(a) describe the reactions of Period 3 elements with oxygen and water;

(b) interpret the ability of elements to act as oxidising and reducing agents.

9.3 Acidic and basic properties of oxides and hydrolysis of oxides

Candidates should be able to:

(a) explain the acidic and basic properties of the oxides of Period 3 elements;

(b) describe the reactions of the oxides of Period 3 elements with water;

(c) describe the classification of the oxides of Period 3 elements as basic, amphoteric or acidic based on their reactions with water, acid and alkali;

(d) describe the use of sulphur dioxide in food preservation.

Sulphur dioxide and sulphites

SO2 and sulphites may be added to such foods as dived fruits, fruit pulp and juices and molasses.

They conserve colour, act as antioxidants and control microbial growth.

Sulphur dioxide and its various sulphites dissolve in water and at low pH levels yield sulphurous acid, bisulphite and sulphite ions.

The various sulphite salts contain 50-68% active sulphur dioxide. A pH dependent equilibrium is formed in water and the proportion of SO2 ions increases with decreasing pH values. At pH values less than 4.0 the antimicrobial activity reaches its maximum.

In the past cut fruits and vegetables in salads bars were sprayed or dipped in a solution of sulphites.

Sulphur inhibits enzymatic browning and keeps plant tissue fresh longer. But this practice has been banned by the FDA because there were over 100 reported cases of adverse reactions including death.

Approximately 5-11% of asthmatics are sensitive to sulphates and experience symptoms such as headaches, nausea, abdominal pains and dizziness.

 

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