MICRO LESSON 1
Electron
Picture it:
Cathode-ray experiments revealed a negative particle.
Simple:
Electrons are negatively charged and found outside the nucleus.
Example:
Electron symbol e⁻.
Remember:
Electron = negative.
Quick Check:
Where are electrons?
MICRO LESSON 2
Proton and Neutron
Picture it:
The nucleus contains positive and neutral particles.
Simple:
Protons are positive; neutrons have no charge.
Example:
Hydrogen nucleus usually has one proton.
Remember:
Nucleus holds p and n.
Quick Check:
Which particle is neutral?
MICRO LESSON 3
Thomson Model
Picture it:
The atom was imagined as electrons embedded in positive matter.
Simple:
Thomson proposed a positive sphere containing electrons.
Example:
Plum pudding model.
Remember:
Positive sphere with electrons.
Quick Check:
What did it fail to explain?
MICRO LESSON 4
Rutherford Experiment
Picture it:
Most alpha particles crossed gold foil; a few deflected; very few returned.
Simple:
The atom is mostly empty space with a small dense nucleus.
Example:
Gold foil experiment.
Remember:
Most pass, few turn, very few return.
Quick Check:
What caused backscattering?
MICRO LESSON 5
Bohr Model
Picture it:
Electrons occupy fixed shells around the nucleus.
Simple:
Electrons move in definite energy levels.
Example:
K, L, M and N shells.
Remember:
Electrons occupy fixed shells.
Quick Check:
Which is first shell?
MICRO LESSON 6
Atomic Number
Picture it:
An element is identified by its proton count.
Simple:
Atomic number equals number of protons.
Example:
Oxygen Z=8.
Remember:
Z = protons.
Quick Check:
How many protons in sodium?
MICRO LESSON 7
Mass Number
Picture it:
Most atomic mass comes from protons and neutrons.
Simple:
Mass number equals protons plus neutrons.
Example:
Carbon-12 has 6p and 6n.
Remember:
A = p+n.
Quick Check:
Find neutrons for A=23, Z=11.
MICRO LESSON 8
Electronic Configuration
Picture it:
Electrons fill shells in order.
Simple:
For early elements K holds 2 and L holds 8.
Example:
Sodium is 2,8,1.
Remember:
Fill inner shells first.
Quick Check:
Write oxygen configuration.
MICRO LESSON 9
Isotopes
Picture it:
Atoms of one element can have different neutron numbers.
Simple:
Isotopes have same atomic number but different mass numbers.
Example:
Hydrogen, deuterium, tritium.
Remember:
Same Z, different A.
Quick Check:
Why are chemical properties similar?
MICRO LESSON 10
Isobars
Picture it:
Different elements can share a mass number.
Simple:
Isobars have same mass number but different atomic numbers.
Example:
Argon-40 and calcium-40.
Remember:
Same A, different Z.
Quick Check:
Are isobars one element?