SPM Chemistry Form 4 Notes – Terminology and Concepts: The Structure of the Atom

by BerryBerryTeacher

in Berry Reference (Notes)

Among the most basic knowledge in chemistry would be understanding the structure of atom. The understanding of terms and concepts of all the important keywords and key phrases would be crucial in gaining further knowledge in chemistry. Fortunately, the structure of atoms has been simplified for SPM Form 4 students to make it less abstract and more intuitive for students to understand them. It will also be helpful to start to memorise the periodic table for now. (If there as anything that you should memorise, it should be the periodic table. As it could save you more time in the long run) Nonetheless, Berry Berry Teacher hopes that everybody try to understand at minimum the following concepts as terminology before moving on to other topics.

SPM Form 4 – Terminology and Concepts: The Structure of the Atom

Important Terms

Matter – anything that occupies space and has mass.

Compound – a substance consists two or more elements that are chemically bonded (molecule or ions).

Element – a substance that cannot be made into anything simpler by chemical reaction.

Atomsmallest particle of an element.

Molecule – a group of two or more atoms.

Ion – a positively charged / negatively charged particle.

Cations positively-charge ions. Example: H+, K+, NH4+ and Mg2+

Anions negatively-charge ions. Example: Br-, OH-, O2- and S2O32-


Velocity of the particle ­ increases when

  • Temperature ­increases
  • Kinetic energy ­increases


Diffusionmovement of particles from a region of high concentration to a region of low concentration.

Changes in the States of Matter

  1. Freezing / Solidification – liquid -> solid
  2. Melting – solid -> liquid
  3. Evaporation – liquid -> gas / vapour
  4. Condensation – gas / vapour -> liquid
  5. Sublimation – gas / vapour -> solid
  6. Sublimation – solid -> gas / vapour

(Sublimation – iodine, ammonium chloride and solid carbon dioxide)


Important Scientist and Their Contributions

Berry Berry Teacher thinks that it will be good if students can link the contribution of each great scientists to their findings. This will allow a chronological understanding of the discoveries (for easier understanding) and to appreciate the work of these fine scientist.

John Dalton (1808) – atomic theory

  1. Atomssmall indivisible particles.
  2. Atoms – neither created nor destroyed.
  3. Atoms – an element are alike.
  4. Atoms – it combine in simple ratio.
  5. Atoms – chemical reactions result from combination / separation of atoms.

J. J. Thomson (1897)

  1. Electrons – negatively-charged particles.
  2. Atoms – positively-charged sphere.

Ernest Rutherford (1911)

  1. Atoms – consists of a positively-charged nucleus with a cloud of electrons surrounding nucleus.
  2. Protons – positively-charged particles.


Niels Bohr (1913)

  1. Electrons – surrounding the nucleus (orbit).

James Cadwick (1932)

  1. Neutrons – electrically neutral subatomic particles.
  2. Neutrons – mass almost the same with a proton.
  3. Nucleus of an atom – consists of protons and neutrons.

Concepts of the Atomic Model

Modern Atomic Model

  1. Nucleus of an atom – consists of protons and neutrons.
  2. Electrons – moving around the nucleus (orbits / electron shells/ quantum shells)


Proton number / Atomic number / Number of protons

  1. Number of protons in its atom.
  2. Number of electrons (neutral atom).

Nucleon number / Mass number / Number of nucleon

  1. Sum of the number protons and neutrons.


Isotopes – atoms of the same element with same proton number but different nucleon numbers.

(Further clarification on isotopes as there are still students who are confused with this concept – Isotopes for any elements simply means that it is another element with the same number of proton and electron but different number of neutrons. It is important to note that the atomic number of isotopes are the same, although the mass number is different. If you can understand this concept, you should be okay)

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