1. Elements and Compounds
Pure Substances
Elements and Compounds

2. Opening Assignment Physical (P) or Chemical property(C)?
1. dissolving sugar in water (solubility)
2. blue color
3. ability to rust
4. melting point
5. reacts with water to form a gas
6. flammability

3. What is matter and how do we describe it?
All matter is made up of Elements
An element is a pure substance….. Can’t be broken down into another substance.

4. Examples of elements

5. What are elements?
They are the simplest substances
There are 92 naturally occurring types of elements.
The smallest atom, and one of the lightest substances, is HYDROGEN.
The biggest atom (and one of the heaviest substances) is URANIUM.
Each of the elements has its own symbol; for example: hydrogen's is H, uranium is U, gold is Au, oxygen is O, copper is Cu ...

6. Atoms Elements are made up one type of atom
An atom is a basic particle -- building blocks

8. Molecules Atoms combine to form molecules
Molecules are larger particles made up of 2 or more atoms held together with chemical bonds

9. Chemical bond
Chemical bond is an attraction between two atoms

10. Molecules
Atoms combine to form larger particles called molecules

11. Sugar molecule – 3 different types of atoms stuck together in a pattern

12. Sugar
The substance sugar is just a collection of many sugar molecules

13. Salt Molecule/Substance salt

14. Modeling Molecules Different colored spheres stand for different atoms

15. Carbon Dioxide CO2

16. Methane CH4

17. Rust
The chemical formula for rust is Fe2O3
How many Fe atoms are there and how many oxygen atoms are there in this compound?

18. Compounds
'A Compound is a pure substance made of 2 or more elements chemically combined
O2 is molecule ….but it is not a compound! You need 2 different elements to form a compound.

19. Other things about compounds
A compound cannot be separated into different substances by mechanical means
When elements combine they form compounds with new physical and chemical properties.

20. Which of these molecules are also compounds?