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SS1: CHEMISTRY - 1ST TERM

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  1. Introduction to Chemistry and Laboratory Apparatus | Week 1
    5Topics
    |
    1 Quiz
  2. Nature of Matter | Week 2
    3Topics
    |
    1 Quiz
  3. Separation Techniques I | Week 3
    1Topic
    |
    1 Quiz
  4. Separation Techniques II | Week 4
    5Topics
    |
    1 Quiz
  5. Particulate Nature of Matter I | Week 5
    5Topics
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    1 Quiz
  6. Particulate Nature of Matter II | Week 6
    9Topics
    |
    1 Quiz
  7. Symbols, Formulae & Oxidation Number | Week 7
    7Topics
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    1 Quiz
  8. Laws of Chemical Combination | Week 8
    4Topics
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    1 Quiz
  9. Chemical Equation & Chemical Combination (Chemical Bonding) I | Week 9
    4Topics
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    1 Quiz
  10. Chemical Combination (Chemical Bonding) II | Week 10
    4Topics
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    1 Quiz
  11. Chemical Combination (Chemical Bonding) III & Shapes of Covalent Molecules | Week 11
    3Topics
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    1 Quiz
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aroms, molecules and ions

Matter is made up of atoms, molecules, and ions.

Atom:

An atom is the smallest particle of an element which can take part in a chemical reaction. Atom is considered to be the basic unit of simple substances or elements.

Molecule:

A molecule is the smallest particle of a substance that can normally exist separately and still retain the chemical properties of that substance.

A molecule is formed by a chemical combination of two or more atoms. These atoms could be of the same element as in the Oxygen molecule (O2) or Chlorine molecule (Cl2). They could also be of a different element as in water (H2O) or sodium chloride (NaCl)

Ions:

An ion is any atom or group of atoms that possess an electrical charge. They are of two types.

1. Cations – Positively charged ions

2. Anions – Negatively charged ions

Atomicity of an Element:

The atomicity of an element is the number of atoms present in each molecule of that element. Most gaseous elements like oxygen, chlorine, nitrogen, hydrogen are diatomic. The molecules consist of two atoms. Rare gases like helium, neon, and argon are monatomic i.e they exist as a single atom.

ElementFormula of moleculeAtomicity
HeliumHe1   –  monoatomic
NeonNe1 – monoatomic
ArgonAr1 – monoatomic
HydrogenH22  – diatomic
OxygenO22  – diatomic
NitrogenN22  – diatomic
ChlorineCl22  – diatomic
OzoneO33 – Triatomic
PhosphorusP44 – Tetraatomic
SulphurS88 – Polyatomic
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