Notes
,🔬 Introduction: Matter and Measurement
— Simple Summary
1. What Is Chemistry?
Chemistry = the study of matter and how it changes.
● Matter = anything that has mass and takes up space.
● Chemistry explains everyday things like:
○ Why food spoils
○ Why batteries work
○ Why leaves change color
○ How medicine works
Chemistry connects what we see (macroscopic world) to what’s happening at the level of
atoms and molecules (submicroscopic world).
2. Atoms, Elements, and Molecules
🧪 Atoms
● The smallest building blocks of matter.
● Each element has its own type of atom.
🧪 Elements
● Pure substances made of only one kind of atom.
● Cannot be broken down chemically.
, ● There are 118 known elements.
● Examples:
○ Oxygen (O)
○ Hydrogen (H)
○ Carbon (C)
🧪 Molecules
● Two or more atoms bonded together.
● Can be:
○ Same element → O₂
○ Different elements → H₂O
3. Compounds vs. Mixtures
🧪 Compounds
● Two or more different elements chemically bonded
● Always have a fixed composition
● Follow the Law of Constant Composition (same percent makeup every time)
Example:
● Water (H₂O) is always 11% hydrogen and 89% oxygen by mass.
● Properties are completely different from hydrogen or oxygen alone.
🧪 Mixtures
● Two or more substances physically combined
● Not chemically bonded
, ● Can vary in composition
● Each substance keeps its own properties
Example:
● Air
● Salt water
● White gold
4. States of Matter
Matter exists in three main states:
State Shape Volume Particle Movement
Solid Fixed Fixed Particles vibrate in place
Liquid Takes shape of Fixed Particles slide past each other
container
Gas Takes shape of No fixed volume Particles far apart and moving
container fast
5. How Matter Is Classified
Everything fits into this chart:
Matter
→ Pure Substance OR Mixture
If it’s a pure substance:
● Element (one type of atom)
● Compound (multiple elements bonded)
If it’s a mixture:
,🔬 Introduction: Matter and Measurement
— Simple Summary
1. What Is Chemistry?
Chemistry = the study of matter and how it changes.
● Matter = anything that has mass and takes up space.
● Chemistry explains everyday things like:
○ Why food spoils
○ Why batteries work
○ Why leaves change color
○ How medicine works
Chemistry connects what we see (macroscopic world) to what’s happening at the level of
atoms and molecules (submicroscopic world).
2. Atoms, Elements, and Molecules
🧪 Atoms
● The smallest building blocks of matter.
● Each element has its own type of atom.
🧪 Elements
● Pure substances made of only one kind of atom.
● Cannot be broken down chemically.
, ● There are 118 known elements.
● Examples:
○ Oxygen (O)
○ Hydrogen (H)
○ Carbon (C)
🧪 Molecules
● Two or more atoms bonded together.
● Can be:
○ Same element → O₂
○ Different elements → H₂O
3. Compounds vs. Mixtures
🧪 Compounds
● Two or more different elements chemically bonded
● Always have a fixed composition
● Follow the Law of Constant Composition (same percent makeup every time)
Example:
● Water (H₂O) is always 11% hydrogen and 89% oxygen by mass.
● Properties are completely different from hydrogen or oxygen alone.
🧪 Mixtures
● Two or more substances physically combined
● Not chemically bonded
, ● Can vary in composition
● Each substance keeps its own properties
Example:
● Air
● Salt water
● White gold
4. States of Matter
Matter exists in three main states:
State Shape Volume Particle Movement
Solid Fixed Fixed Particles vibrate in place
Liquid Takes shape of Fixed Particles slide past each other
container
Gas Takes shape of No fixed volume Particles far apart and moving
container fast
5. How Matter Is Classified
Everything fits into this chart:
Matter
→ Pure Substance OR Mixture
If it’s a pure substance:
● Element (one type of atom)
● Compound (multiple elements bonded)
If it’s a mixture:
