Chemistry Form 4: Chapter 4 - Reactivity of Group 17

• When a halogen atom reacts, it gains an electron to form a singly charged negative ion which has a stable noble gas electron arrangement.
• As you go down the group of 17, the atomic radius gets bigger due to an extra filled electron shell. 
• The valence electron is further and further away from the nucleus.
• The forces of attraction between the nucleus and the valence electrons become weaker, making it more difficult to gain electrons.
• Therefore, the halogen is less reactive down the group.

Physics Form 5: Chapter 3 - Forces between Two Current Carrying Conductors

• When two current-carrying conductors with current flowing in the same direction, a weak magnetic field is produced in the region between the conductors. The two conductors attract each other.
• When two current-carrying conductors with current flowing in the opposite direction, a stronger magnetic field is produced in the region between the conductors. The two conductors repel each other.

Malaysian Kids Trail Asian Powerhouses in Science and Maths

KUALA LUMPUR, April 28 — The wide gap between Malaysian students and their counterparts in first-tier Asian countries like Korea, Singapore and Taiwan could threaten its ambitions to be a high income nation said the UN 2010 Millennium Development Goal (MDG) report released today. The report states that for the mathematics benchmarks in TIMSS (Trends in International Mathematics and Science Study) 2007, fewer than 20 per cent of Malaysian students achieved the high benchmark and about 50 per cent achieved the intermediate benchmark, compared with 70 per cent and 85–90 per cent respectively for the first-tier Asian economies.

“The Asian region has a clear gap in the distribution of achievement between the first tier Asian economies represented by the Republic of Korea, Singapore and Taiwan, China; and the second-tier countries represented by Indonesia, Malaysia and Thailand,” said the MDG report. Malaysian students’ performance had also declined at all levels from 1999 to 2007 but the report said it was partly because some of the cognitive domain specifications tested in TIMSS 2007 had not been covered in Malaysia’s mathematics curriculum.

“Nevertheless, the TIMSS 2007 mathematics and science results need to be further analysed, as they may suggest some obstacle to Malaysia’s ability to realise its ambitions of becoming a high income nation,” it said.
The Najib administration is attempting to transform Malaysia into a high-income economy by 2020 with an emphasis on productivity, efficiency and innovation. But observers contend that it would require significant structural reforms, including in education that so far appear to be lacking. Malaysian universities also lag behind their Asian counterparts.

No Malaysian university made it to the Times Higher Education (THE) 2010-11 ranking of top 50 Asian universities or the ranking of top 200 global universities. In contrast, Singapore had three universities in the THE top 200 global universities, Hong Kong had eight, while Japan and Korea had five each. The MDG report noted, however, that Malaysia is close to achieving the MDG goal of ensuring that all children will be able to complete a full course of primary education by 2015.

Chemistry Form 4: Chapter 4 - Physical Properties of Halogen

• The melting and boiling points increases down the group as the atomic radius increase.
• The van der Waals become stronger and thus more heat energy is needed to overcome these forces between the molecules.
• The physical state of halogens change gradually from gas to liquid to solid due to an increase in melting and boiling point.

Check Your Matriculation Application

PETALING JAYA: Those who have applied for matriculation programmes can check the status of their applications tomorrow. The Education Ministry said this concerned students who had completed their Sijil Pelajaran Malaysia and had applied from July 10 to Oct 10 last year. The students are also advised to visit the ministry's website at http://www.moe.gov.my before keying in their identity card number.

Alternatively, applicants may also check via SMS by typing MOE MAT, followed by their identity card number before sending the message to 15888. The ministry's matriculation department can also be contacted at 03-8884 4088 from tomorrow. The hotlines are open on working days from 8.30am to 4.30pm.

Further questions regarding registration and fees may be obtained by visiting the ministry's website or by contacting the respective matriculation or Mara colleges. The registration date for matriculation students is May 23. Unsuccessful applicants may make appeals through the ministry's hotline or website until May 13.

Studying in Australia now very expensive.

 The Star, Tuesday April 26, 2011

PETALING JAYA: The strengthening ringgit is not doing parents with children in Australia any favour.
Although the ringgit was at 2.99 against US$1 yesterday, it stood at 3.22 against A$1. Teacher Carey Lee, 54, now had to fork out around RM20,000 more a year compared to 2009 when the exchange rate was 2.9.
She said she might consider bringing her son back to Malaysia if he did not do well. Lee is paying around RM100,000 a year for his studies there.

Banker David Chan, 54, said there was little Malaysian parents could do. “It's painful that things cost the same on a dollar-to-dollar basis. For example, a plate of noodles costing RM5 is also A$5 there. That's RM16 after conversion,” he said, adding that his son still had four years to go in Adelaide. Accountant Thomas Wong said he was amazed that the Australian economy was still strong despite the massive floods and fires there. He said his son's school fees had jumped from RM28,000 per term to RM32,000 in the 18 months he was there.

Writer P. Steven, 43, said his burden was eased slightly after his daughter got a partial scholarship this year.
“She also moved out of the campus residence to a house. That's cheaper. She also uses a bicycle to get to campus,” he said, adding that the exchange rate was a continuous worry. It was reported last month that there are some 23,000 Malaysian students in Australia.

Test Your Reaction Time

Click on the diagram below to play!

Physics Form 4: Chapter 2 - Elevator System

N is a normal reaction force that indicates the reading of the weighing machine.

Students Expulsions on the Rise in Penang

MORE secondary school students were expelled in Penang last year compared to 2009. Last year, 830 students were expelled from secondary schools in Penang because of disciplinary issues including truancy, compared to 760 in 2009. Central Seberang Prai district Education Department officer Mohd Zaki Harun, who disclosed this, said 546 secondary school students were involved in criminal misdemeanours in Penang last year. The department also recorded truancy cases involving 391 secondary school students and 275 primary school pupils last year.

The students were either expelled, suspended or issued warnings. “We view this matter seriously and have instructed all school heads to initiate efforts to contain the problem. Truancy is a worrying issue,” he said.
Mohd Zaki said that a holistic approach involving teachers, parents, and the community was needed.

“Teachers must give due attention to problem students by getting them involved in activities that enable them to gain knowledge to stand on their own feet when they leave school,” he said. Among other disciplinary problems were gambling, theft, engaging teachers and prefects in fights, extortion, bullying, involvement with triads, bringing weapons to school, threatening students and outraging of modesty.

Physics Form 5: Chapter 3 - Direct Current Motor

 

How the motor is able to rotate:

• The flow of current produces a magnetic field in the coil / armature
• Magnetic field generated by the current interact with the magnetic field of permanent magnet.
• The resultant magnetic field produced is called a lastic field / catapult field.
• The lastic field causes two forces acting on the rectangular coil in opposite directions which enable the rotation.
  
  
  
  

Chemistry Form 4: Chapter 4 - Reactivity of Group 1

Reactivity of Group 1 increases when go down the group.

WHY?

• When an alkali metal atom reacts, it loses an electron to form a singly positively charged ion which is a stable noble gases electron arrangement.
• When go down the group, the atomic radius gets bigger due to an extra filled electron shell and the outer electron is further and further away from the nucleus.
• Therefore the outer electron is less strongly held by the positive nucleus as the attractive force is decreased.
• As a result, the outer electron is more easily lost and react more vigorously.
  
  Reaction of Group 1 with water

Physics Form 5: Chapter 2 - Electric Bell (Application of Electromagnet)

• When the switch is pressed, a current flows through the solenoids and the electromagnets attract a soft-iron plate.
• The striker hits the gong and a sound is produced.
• The movement of the soft-iron plate breaks the contact and the circuit is cut off.
• The electromagnet loses its magnetism and the striker springs back to original position.

Click on the diagram below to play!

Physics Form 5: Chapter 3 - Forces on a Current-carrying Wire

The direction of the magnetic force, F acting on the wire can be determined by using Fleming’s left hand rule.





Explanation:

• The straight lines with arrows show the direction of the magnetic field between the north and south poles.
• The circular lines with arrows show the direction of the magnetic field of the current.
• When the two fields are in the same direction and they produce a stronger combined magnetic field. 
• When the two fields act in opposite directions and they produce a weaker magnetic field.
• Interaction between the magnetic fields produce a catapult field. Thus, the wire carrying current experiences a resultant force in the direction from the stronger to the weaker magnetic field
  
  
  

Types of Teacher

What types of your school teacher?

The mediocre teacher tells

The good teacher explains

The superior teacher demonstrates

The great teacher inspires 

Physics Form 4: Chapter 2 - Pulley System

By using F = ma from Newton's Second Law of Motion, we are able to determine the acceleration and tension of the pulley system.

Click on the diagram to play!

Horizontal Pulley

Inclined Pulley

Chemistry Form 4: Chapter 4 - Physical Properties of Group 1 Elements

• Group 1 elements are soft metal and can be cut with a knife

• Silvery grey surface

 

• Low density compared to other metals

• Lower melting and boiling points than most other metals
  
  

As the atomic radius increases, the charges are further apart and the electrical attractive force is reduced. This results a weaker metallic bond and little heat energy is needed to overcome the bond. Thus, the melting/boiling point decreases as we go down the group.

Physics Form 5: Chapter 3 - Electromagnet

• An electromagnet is a coil which can produce a magnetic field when a current passes through it and losses all its magnetism when the current is switched off.
• Soft-iron is suitable to use as a core because it can be magnetized and demagnetized easily and also soft iron can concentrate the magnetic field.
• The steel core magnet remains magnetised when the current is switched off. Therefore, steel is not suitable as the core of electromagnets. Anyway, steel is suitable to use as a bar magnet.

Click on the diagram below to play!

The strength of a electromagnet can be increased by:

• increasing the current flowing through the coil
• increasing the number or turns.
• the use of a soft iron core

Modular system for STPM next year

PETALING JAYA: The introduction of a modular system for assessing the Sijil Tinggi Persekolahan Malay­sia (STPM) examinations will begin next year, and not this year as originally scheduled.
Deputy Education Minister Datuk Dr Wee Ka Siong said the system would be based on three semesters and students would be evaluated at the end of each one.

“This will be similar to the system in place at universities to help students adjust to the sort of continuous assessment involved in tertiary study,” he said.
“Due to the logistics involved following the change, we will only start the modular system with Lower Six students next year. “However, the content of the STPM syllabus will remain the same,” he told The Star yesterday.

In 2009, it was reported that the existing terminal system for STPM assessments would be replaced by a modular one in 2011. Dr Wee added that the modular assessment would also include coursework and school-based projects.

Physics Form 5: Chapter 3 - Electromagnetism

• Electromagnetism is produced when an electrical current flows through a conductor.

• A small magnetic field is created around the conductor with the direction of this magnetic field with regards to its "North" and "South" poles being determined by the direction of the current flowing through the conductor

Magnetic field produced by a single wire:

 

 

Magnetic field produced by a loop:

 

Magnetic field by a solenoid

By using right-hand grip, north or south pole can be determined.

 

 

When current is passed through a solenoid, it act as a bar magnet!

Physics Form 4: Chapter 2 - Newton's Second Law of Motion

F=ma

Newton's second law of motion can be stated as follows:

The rate change of momentum of an object  is directly proportional to the magnitude of the resultant force, in the same direction as the resultant force, and inversely proportional to the mass of the object.

 

Chemistry Form 5: Chapter 2 - Esterification

Esterification is a chemical reaction between carboxylic acid combines with an alcohol in the presence of a catalyst (commonly concentrated sulphuric acid) to form an ester.

Examples of Esters

• methyl butanoate (apple) :
  

  methanol	+	butanoic acid	→	methyl butanoate (ester)	+	water
  CH3OH	+	C3H7COOH	→	C3H7COOCH3 (ester)	+	H2O

• ethyl methanoate (rum essence) :
  

  ethanol	+	methanoic acid	→	ethyl methanoate (ester)	+	water
  C2H5OH	+	HCOOH	→	HCOOC2H5 (ester)	+	H2O

• ethyl butanoate (pineapple) :
  

  ethanol	+	butanoic acid	→	ethyl butanoate (ester)	+	water
  C2H5OH	+	C3H7COOH	→	C3H7COOC2H5 (ester)	+	H2O

• pentyl ethanoate (banana) :
  

  pentanol	+	ethanoic acid	→	pentyl ethanoate (ester)	+	water
  C5H11OH	+	CH3COOH	→	CH3COOC5H11 (ester)	+	H2O

• pentyl butanoate (apricot) :
  

  pentanol	+	butanoic acid	→	pentyl butanoate (ester)	+	water
  C5H11OH	+	C3H7COOH	→	C3H7COOC5H11 (ester)	+	H2O

• octyl butanoate (orange) :
  

  octanol	+	butanoic acid	→	octyl butanoate (ester)	+	water
  C8H17OH	+	C3H7COOH	→	C3H7COOC8H17 (ester)	+	H2O

• methyl ethanoate (solvent) :
  

  methanol	+	ethanoic acid	→	methyl ethanoate (ester)	+	water
  CH3OH	+	CH3COOH	→	CH3COOCH3 (ester)	+	H2O

• ethyl ethanoate (solvent) :
  

  ethanol	+	ethanoic acid	→	ethyl ethanoate (ester)	+	water
  C2H5OH	+	CH3COOH	→	CH3COOC2H5 (ester)	+	H2O

Esterification by refluxing