MICRO LESSON 1
Conservation of Mass
Picture it:
In a closed reaction, total matter remains present even when substances change.
Simple:
Mass is neither created nor destroyed.
Example:
Reactant mass equals product mass.
Remember:
Matter changes form, not total mass.
Quick Check:
What happens to mass in a closed reaction?
MICRO LESSON 2
Constant Proportions
Picture it:
Water always contains hydrogen and oxygen in fixed proportion.
Simple:
A compound always contains the same elements in the same mass ratio.
Example:
Water composition remains fixed.
Remember:
Same compound, same proportion.
Quick Check:
Can water have random ratios?
MICRO LESSON 3
Atom
Picture it:
Atoms are the smallest chemical units of elements.
Simple:
An atom is the smallest particle that takes part in a reaction.
Example:
H, O, Na and Cl.
Remember:
Atom is the basic chemical unit.
Quick Check:
Can most atoms exist alone?
MICRO LESSON 4
Molecule
Picture it:
Atoms join chemically to form molecules.
Simple:
A molecule contains two or more bonded atoms.
Example:
O₂, H₂O and CO₂.
Remember:
Molecule = bonded atoms.
Quick Check:
How many atoms are in H₂O?
MICRO LESSON 5
Ions
Picture it:
Atoms may gain or lose electrons and become charged.
Simple:
A cation is positive and an anion negative.
Example:
Na⁺ and Cl⁻.
Remember:
Cation positive, anion negative.
Quick Check:
Which ion is positive?
MICRO LESSON 6
Valency
Picture it:
Atoms combine according to their combining capacity.
Simple:
Valency is the combining capacity of an atom or ion.
Example:
Hydrogen 1, oxygen 2.
Remember:
Valency builds formulae.
Quick Check:
What is chloride valency?
MICRO LESSON 7
Writing Formulae
Picture it:
Valencies tell how many atoms are needed.
Simple:
Write symbols, write valencies, cross and simplify.
Example:
Ca²⁺ and Cl⁻ give CaCl₂.
Remember:
Cross valencies, simplify.
Quick Check:
Write aluminium oxide.
MICRO LESSON 8
Atomic and Molecular Mass
Picture it:
A molecule's mass is the sum of its atomic masses.
Simple:
Molecular mass is total atomic mass.
Example:
H₂O = 2×1+16 = 18 u.
Remember:
Add all atoms.
Quick Check:
Find CO₂ mass.
MICRO LESSON 9
Mole Concept
Picture it:
Chemists count tiny particles using moles.
Simple:
One mole contains 6.022×10²³ particles.
Example:
One mole of water molecules.
Remember:
Mole is chemistry's counting unit.
Quick Check:
What is Avogadro number?