Friday, February 22, 2013

Physics Form 4: Chapter 5 - Concave Lens Ray Diagrams


Concave lens is a diverging lens. The image form is smaller than the object, virtual and upright. Concave lens always produce images that share these characteristics. The location of the object does not affect the characteristic of the image.






Thursday, February 21, 2013

Chemistry Form 4: Chapter 2 - Structure of an Atom

   
  • Atom consists of electrons surrounding a nucleus that contains protons and neutrons.
  • Electrons are arranged around the nucleus in energy levels or shells. 
  • The mass of an atom is concentrated in nucleus which contained the protons and neutrons.
  • The nucleus is positively charged because of the presence of protons which are positively charged and the neutrons are neutral.
  • The atom is neutral because the number of protons and the number of electrons are equal

 Subatomic particles
    Symbol
 Relative mass
    Relative   charged
   Position
Proton
P
1
+1

  Nucleus
Neutron
N
1
0
Electron
e-
  1/1837 » 0
-1
  Orbit

Symbol of Element