Lesson 1: Understanding Atoms
Beginner
What is an Atom?
Atoms are the basic building blocks of matter. Everything around you is made of atoms - from the air you breathe to the device you're using right now.
Nucleus: The dense center of the atom containing protons and neutrons.
Protons: Positively charged particles in the nucleus.
Neutrons: Neutral particles in the nucleus.
Electrons: Negatively charged particles orbiting the nucleus.
Proton
Charge: +1
Mass: ~1 amu
Neutron
Charge: 0
Mass: ~1 amu
Electron
Charge: -1
Mass: ~0 amu
Atomic Structure
Atoms are mostly empty space. If an atom were the size of a football stadium, the nucleus would be about the size of a marble at the center, and the electrons would be like tiny specks in the stands.
This visualization shows the relative size of the nucleus (red dot) compared to the electron cloud (blue dots).
Lesson 1 Quiz
1. What are the three main subatomic particles that make up an atom?
A) Protons, neutrons, and electrons
B) Protons, electrons, and ions
C) Neutrons, electrons, and molecules
D) Protons, neutrons, and photons
Correct! Protons, neutrons, and electrons are the three main subatomic particles.
2. Where is most of the mass of an atom located?
A) In the electron cloud
B) In the nucleus
C) Evenly distributed throughout the atom
D) In the space between the nucleus and electrons
Correct! The nucleus contains nearly all of an atom's mass.
3. What is the charge of a neutron?
A) Positive (+1)
B) Negative (-1)
C) Neutral (0)
D) It varies
Correct! Neutrons are neutral particles with no charge.
Lesson 2: Chemical Bonds
Intermediate
Types of Chemical Bonds
Chemical bonds are the attractive forces that hold atoms together in compounds. There are three primary types of chemical bonds:
Ionic Bonds
Formed by transfer of electrons
Between metals and non-metals
Covalent Bonds
Formed by sharing electrons
Between non-metals
H — H
Metallic Bonds
Electron "sea" model
Between metal atoms
Cu — Cu — Cu
Ionic Bond Example: Sodium Chloride (NaCl)
1. Sodium (Na) donates its valence electron to chlorine (Cl)
2. Sodium becomes positively charged (Na+)
3. Chlorine becomes negatively charged (Cl-)
4. The opposite charges attract, forming an ionic bond
Covalent Bonding
Covalent bonds form when atoms share electrons to achieve a full outer shell. This type of bond is common between non-metal atoms.
Water Molecule (H₂O)
1. Oxygen has 6 valence electrons and needs 2 more to complete its outer shell
2. Each hydrogen has 1 valence electron and needs 1 more
3. Oxygen shares one electron with each hydrogen, forming two covalent bonds
Single Bond
One shared pair of electrons
H—H (Hydrogen molecule)
Double Bond
Two shared pairs of electrons
O=O (Oxygen molecule)
Lesson 2 Quiz
1. Which type of bond involves the transfer of electrons from one atom to another?
A) Covalent bond
B) Ionic bond
C) Metallic bond
D) Hydrogen bond
Correct! Ionic bonds form through electron transfer.
2. In a water molecule (H₂O), how many covalent bonds does the oxygen atom form?
Correct! Oxygen forms two covalent bonds in water - one with each hydrogen atom.
3. Which of the following best describes metallic bonding?
A) Sharing of electron pairs between atoms
B) Transfer of electrons from one atom to another
C) A "sea" of delocalized electrons surrounding positive metal ions
D) Weak attraction between polar molecules
Correct! Metallic bonds involve a "sea" of delocalized electrons.
Lesson 3: States of Matter
Beginner
The Three Common States of Matter
Matter exists in different states depending on temperature and pressure. The three most common states are solid, liquid, and gas.
Solid
- Definite shape and volume
- Particles vibrate in place
- Strong intermolecular forces
Liquid
- Definite volume, no definite shape
- Particles can slide past each other
- Moderate intermolecular forces
Gas
- No definite shape or volume
- Particles move freely
- Weak intermolecular forces
Particle Behavior
The state of matter depends on how particles interact with each other and how much energy they have.
Energy: As you add energy (heat), particles move faster and overcome intermolecular forces.
Pressure: Increasing pressure can force particles closer together, favoring solid or liquid states.
Temperature: Higher temperatures give particles more kinetic energy, favoring gas states.
Plasma
The fourth state of matter at very high temperatures
Found in stars and lightning
Bose-Einstein Condensate
The fifth state of matter at extremely low temperatures
Near absolute zero (-273°C)
Lesson 3 Quiz
1. Which state of matter has a definite volume but no definite shape?
A) Solid
B) Liquid
C) Gas
D) Plasma
Correct! Liquids have a definite volume but take the shape of their container.
2. What is the process called when a solid changes directly to a gas without becoming a liquid first?
A) Melting
B) Freezing
C) Sublimation
D) Condensation
Correct! Sublimation is when a solid changes directly to a gas (like dry ice).
3. Which of the following is NOT true about gases?
A) They have no definite shape
B) They have no definite volume
C) Their particles are tightly packed together
D) They expand to fill their container
Correct! Gas particles are not tightly packed - they have lots of space between them.