Unit 1: Matter & Energy
Matter is anything that has mass and takes up space, but in chemistry the goal is to understand
how different types of matter behave and change. Everything you see fits into patterns, and
once you learn those patterns, chemistry gets way easier.
Types of Matter
● Element → one type of atom (O, Fe)
● Compound → elements chemically bonded (H₂O, CO₂)
● Mixture
○ Homogeneous → evenly mixed (salt water)
○ Heterogeneous → not evenly mixed (sand + water)
Key idea:
If it can be separated physically, it’s a mixture, not a compound.
Physical vs Chemical Changes
● Physical change
○ no new substance
○ examples: melting, cutting, dissolving
● Chemical change
○ new substance forms
Matter is anything that has mass and takes up space, but in chemistry the goal is to understand
how different types of matter behave and change. Everything you see fits into patterns, and
once you learn those patterns, chemistry gets way easier.
Types of Matter
● Element → one type of atom (O, Fe)
● Compound → elements chemically bonded (H₂O, CO₂)
● Mixture
○ Homogeneous → evenly mixed (salt water)
○ Heterogeneous → not evenly mixed (sand + water)
Key idea:
If it can be separated physically, it’s a mixture, not a compound.
Physical vs Chemical Changes
● Physical change
○ no new substance
○ examples: melting, cutting, dissolving
● Chemical change
○ new substance forms
