UNIT 2: C H E M I S T R Y
Science 10
● Law of Conservation of Energy: Energy cannot be created or destroyed just
converted from one form → another
● Law of Definite Composition: Compounds are pure substances that contain 2+
elements in fixed proportions
● Law of Conservation of Mass: Total input mass = total output mass
- - - important laws
Element: pure substance containing only ONE type of atom → has its own properties +
cant be broken down further
Ex. Iron, Sodium, Oxygen
Compound: 2+ elements in a fixed ratio → can only be broken down through chemical
change
❗❗Dalton’s Atomic Theory:
Ex. Calcium Chloride, water (H20)
**very important**
1. Atoms are unchangeable and unbreakable
2. Atoms of an element are identical in size and mass
3. Elements can be combined in fixed proportion to make
compounds
4. Chemical reactions are the rearrangement of atoms unto
new groupings
Model of an Atom:
-
Science 10
● Law of Conservation of Energy: Energy cannot be created or destroyed just
converted from one form → another
● Law of Definite Composition: Compounds are pure substances that contain 2+
elements in fixed proportions
● Law of Conservation of Mass: Total input mass = total output mass
- - - important laws
Element: pure substance containing only ONE type of atom → has its own properties +
cant be broken down further
Ex. Iron, Sodium, Oxygen
Compound: 2+ elements in a fixed ratio → can only be broken down through chemical
change
❗❗Dalton’s Atomic Theory:
Ex. Calcium Chloride, water (H20)
**very important**
1. Atoms are unchangeable and unbreakable
2. Atoms of an element are identical in size and mass
3. Elements can be combined in fixed proportion to make
compounds
4. Chemical reactions are the rearrangement of atoms unto
new groupings
Model of an Atom:
-
