1. Chapter 17 Section 1 Part A
Composition of Matter

2. Pure Substances
Pure substances cannot be broken down and still have the same properties
Properties are characteristics we can describe or measure
Two kinds of pure substances:
Elements
Compounds

3. Elements Elements make up all matter
Elements are made up of atoms that are similar
Atom: smallest part an element can be broken into and still have the properties of the element
Atoms made up of 3 subatomic particles
Protons
Neutrons
Electrons

4. Elements 90 naturally occurring elements
Organized on the periodic table
Elements can be broken into 3 groups:
Metals
Nonmetals
Metalloids
Each atom of the same element has the same number of protons (ALWAYS!)

5. Compounds Compounds are chemical combinations of two or more elements
The atoms are always in the same ratio in a compound
Example: water is
Bonding holds the atoms of compounds together
Two kinds of bond:
Ionic
Covalent

6. Compounds Compounds are formed by chemical reaction
Atoms break and re-form bonds in a chemical reaction
The only way we can change an element is by a nuclear reaction
Two main kinds of nuclear reaction:
Fusion:
Fission:

7. Fusion vs Fission Fusion: Fission:
Two atoms come together to make a larger atom
Occurs in stars
Fission:
Atom breaks apart into smaller atom(s)
Occurs in radioactive elements