Q1 Zinc nitrate reacts with aqueous ammonia (NH4OH) to form a salt and a base.  (i) Name the salt and the base. (ii) Describe the observations for the reaction. (iii) Write a chemical equation for the reaction (include state symbols). (iv) Write an ionic equation for the reaction.  Q2 Ammonium sulfate is heated with sodium hydroxide. (i) Write a chemical equation (include state symbols) for the reaction. (ii)  Describe a test for the gas. Q3 An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution.  (i) The gas produced turns damp red litmus paper blue.  Name the gas evolved. (ii) This is a confirmatory test for an anion.  Name this anion.  (iii) Give a possible cation which gives the green solution. Q4 Sulfuric acid is titrated with potassium hydroxide in the preparation of potassium sulfate salt.  (i) Explain why this method is recommended for the preparation for this salt.  (ii) Write an ionic equation for the reaction. Q5 Excess zinc carbonate is added to hydrochloric acid in the preparation of zinc chloride salt. (i) Write an ionic equation for the reaction. (ii)  Why excess zinc carbonate is used? (iii) Briefly explain how the zinc chloride crystals can be obtained. Please post your excellent answers in your blog (15 marks).  Deadline for online homework : 23rd Sept 2011 (Friday). SEPTEMBER HOLIDAY HOME : Please refer to the Longman Effective Guide to 'O' level Chemistry to complete the Revision Exercise 4 (page 107 to 109) Do the Multiple Choice Questions Q1 to Q10 and the Structured Questions Q1 to Q5. Do on A4 size paper.  Don't need copy out the questions.  For the Structured questions, please show working. Deadline : Pass to me when school reopens. JUNE HOLIDAY HOMEWORK : Each Group will choose one of the section on Metals shown below : Q1) Properties and Uses of Metals (e.g. density, melting point, uses of copper, aluminium, etc). Q2) Reactivity of Metals (e.g. with water, steam, acids, oxygen, etc). Q3) Extraction of Metals (e.g. extract sodium, iron, copper, gold, etc).  Individual Groups will select one section on metals and do a research study.  Prepare 25 to 30 powerpoint slides with some pictures, etc.  (PLEASE READ THE CHEMISTRY TEXTBOOK ON THE TOPIC OF METALS TO UNDERSTAND WHAT YOU NEED TO KNOW ABOUT METALS). Assessment : 10 marks to be awarded : i) Details & Relevant 5 marks   ii) Quality, Creativity 5 marks Deadline : submit your ppt. to your teacher on 19th July 2011 (Tuesday).  Thanks.
Names of students	Index No.	i) Details & Relevant 5 marks	ii) Quality, Creativity 5 marks
Ysabelle	01	5	5
Cindy	02	5	5
Charmaine	03	5	5
Grace	04	4	4
Shin Yoong	05	4	4
Eiei	06	5	5
Xue Li	07	5	5
Chelsea	08	5	5
Janis	09	5	5
Zi Qing	10	5	5
Hwee Leng	11	4	4
Shu Yu	12	4	4
Jie En	13	5	5
Agnes	14	5	5
Siukgeok	15	4	4
Wan Ling	16	4	4
Nicole	17	5	5
Kai Qi	18	5	5
Xue Ting	19	5	5
Rupini	20	5	5
Xin Hui	21	5	5
Yi Hui	22	5	5
Cek Min	23	5	5
Su	24	5	5
Ming Siew	25	5	5
Yi Jing	26	4	4
Aleen	27	5	5
Wendy	28	5	5
Yi Ting	29	5	5
Michelle	30	5	5
Aaron	31	3	5
Clarence	32	3	5
Xin Kang	33	4	4
Fabian	34	4	4
Helmi	35	4	4
Jia Le	36	5	5
Ze Wei	37	4	4
Jun Wei	38	5	5
Chun Boon	39	4	4
Jun Jie	40	3	5
Zane	41	3	5
Li Zhi	42	5	5

PLEASE memorise thoroughly THE STRUCTURES AND PROPERTIES OF IONIC COMPOUNDS, SIMPLE COVALENT MOLECULES, MACROMOLECULAR STRUCTURES & METALLIC ELEMENTS.....(see below)

	Ionic Bond	Covalent Bond	Metallic Bond
Ionic Lattice Structure : formed by the transfer of electrons from a metal to a non-metal to achieve a complete outermost shell, which is stable. Physical Properties : i) usually solid. ii) high melting point & boiling point. iii) high density. iv) conducts electricity in molten state and aqueous state but not in solid state. v) usually soluble in water but not in organic solvents.	Ionic-bonded  compounds have strong electrostatic forces between the positive ions and negative ions, in its ionic lattice structure (when it is in solid form). Examples : usually ionic-bonded solids and aqueous solutions, e.g. NaCl, MgO, Ca(NO3)2, etc.
Simple Molecular Structure : Formed by the sharing of electrons between non-metals to achieve a complete outermost shell, which is stable. Properties : i) usually gas and liquid. ii) low melting point & boiling point. iii) usually low density. iv) does not conduct electricity.		Covalent-bonded molecules have weak intermolecular forces between the molecules, which is easily separated by using little energy. Examples : usually gases and liquids, e.g. O2, N2, CO2, H2O, etc.
Macromolecular Structure : Formed by strong covalent bonds between non-metals to form a large structure, e.g. tetrahedral structure of diamond, layer structure of graphite. Properties : i) usually solid. ii) very high melting point & boiling point. iii) diamond does not conduct electricity. iv) diamond is very hard. v) graphite conducts electricity. vi) graphite is soft & slippery.		Diamond has a tetrahedral structure which consists of one carbon atom covalently bonded to four carbon atoms.  A lot of energy is needed to break all the covalent bonds and tetrahedral structure to melt it. e.g. diamond, silicon dioxide. Graphite has a hexagonal layer structure which consists of one carbon atom covalently bonded to three carbon atoms, with a free-moving electron moving along the layer.  There are weak intermolecular forces between the layers.
Metallic Structure : Formed when the metal atoms give away their valence electrons, resulting in a ‘sea’ of free-moving electrons moving  around the fixed positive ions. Properties : i) usually solid. ii) high melting point & boiling point. iii) metals conduct electricity in solid state and molten state.			Metallic bond is the attraction between the ‘sea’ of free-moving electrons and the fixed positive ions in the metal. e.g. iron, copper, sodium metal, etc. Metals can conduct electricity because  the free-moving electrons can carry electric charges around in a circuit.

THE VIDEO BELOW EXPLAINS HOW METALLIC BONDS ARE FORMED.  Please watch it to understand.....

Metallic Bonding : courtesy from the youtube video from http://www.youtube.com/watch?v=c4udBSZfLHY






















ASSESSMENT MARKS FOR ATOMIC STRUCTURE ASSIGNMENT

Please see the table below for the marks scored by individual student.

What are we looking for?	Max Mark	Level 1	Level 2	Level 3
Ability to answer.	5	1 Post’ incomplete answers. Lack originality.	3 Post’ acceptable answers to the questions. Originality of the answers.	5 Post’ detailed and excellent answers to the questions with minimum error. Creative answering skills. Originality of the answers.
Collaborative learning.	5	1 ‘Post’ comments on 3 friends’ answers seen in your blog.	3 ‘Post’ good comments on 3 friends’ answers seen in your blog.	5 ‘Post’ Excellent comments on 3 friends’ answers seen in your blog.
Ownership of blog.	5	1 Minimum : profile, photos, blog design, message box, etc.	3 Acceptable : profile, photos, blog design, message box, etc.	5 Excellent : profile, photos, blog design, message box, etc.

     New MRT in Seville of Spain

    My trip to France, Paris Dec 2010

Hello all, I have explained the concepts of an atomic structure in my last few lessons.  I am quite sure you are keen to share your understanding with all the bloggers and me....write as much as you can about it...., I will be very impressed!! Please enjoy completing the assignments below :

1. What does an atom looks like?  What are the sub-atomic particles inside it.....(talk about electrons, neutrons, protons, electron shells, nucleus....)

2. Draw the atomic structure of a sodium atom and a sodium ion....explain why you draw it this way.

3. Draw the atomic structure of a sulfur atom and a sulfide ion....explain why you draw it this way.

4. Chlorine-35 atom and Chlorine-37 atom are called isotopes...Use these two examples to explain what is 'isotopes'.

5. Sodium is a metal and sulfur is a non-metal....why we classify them this way??

Courtesy from the youtube video - http://www.youtube.com/watch?v=-P4N-0Wbtyk (by fizzicsorg)