1. Elements and Compounds

2. Key Concepts: Atoms and Elements
There are billions of materials on Earth.
All of those materials are made up from only about 100 elements.
Elements are formed from only one type of atom.
Compounds are formed from two or more different types of atoms.

3. An element is a substance that is made from one kind of atom only
An element is a substance that is made from one kind of atom only. It cannot be broken down into simpler substances.
atom
atom
An element
An element

4. A compound is a substance that is made from more than one element.
atom
atom
A compound made up of 2 different elements
A compound made up of 7 different elements

5. A compound can be broken down into elements
An element
An element
A compound made up of 3 different elements
An element

6. Elements and compounds examples:
Elements can have single atoms that are not bonded to one another, like this sample of Argon gas.
Elements can have atoms that are bonded to one another, like this sample of Nitrogen gas.
Compounds have atoms of more than one kind of element that are bonded to one another, like this sample of water.

7. Substances
always or
Molecules

8. Watch out for these tricky ELEMENTS H2 = Hydrogen F2 = Fluorine
N2 = Nitrogen
Cl2 = Chlorine
O2 = Oxygen H F N Cl O

9. The number after the symbol tells how many of that element is present in the molecule.
H2 = Hydrogen
Two hydrogens
CO2 = One Carbon and 2 Oxygen
When no number is shown, there is an understood 1.
NaCl = one Sodium and one Chlorine H O C Na Cl

10. Water Methane Carbon dioxide Oxygen Chalk Table salt Caffeine Sulfur
Material
Made up of:
Element or compound
Water
Hydrogen and Oxygen
Methane
Carbon and Hydrogen
Carbon dioxide
Carbon and Oxygen
Oxygen
Chalk
Calcium, Carbon & Oxygen
Table salt
Sodium & Chlorine
Caffeine
Carbon, Hydrogen, Nitrogen & Oxygen
Sulfur

11. Water Compound Methane Carbon dioxide Oxygen Element Chalk Table salt
Material
Made up of:
Element or compound
Water
Hydrogen and Oxygen
Compound
Methane
Carbon and Hydrogen
Carbon dioxide
Carbon and Oxygen
Oxygen
Element
Chalk
Calcium, Carbon & Oxygen
Table salt
Sodium & Chlorine
Caffeine
Carbon, Hydrogen, Nitrogen & Oxygen
Sulfur

12. Water H2O Methane CH4 Carbon dioxide CO2 Oxygen O2 Chalk CaCO3
Material
Chemical Formula
Element or compound?
Water
H2O
Methane
CH4
Carbon dioxide
CO2
Oxygen O2
Chalk
CaCO3
Table salt
NaCl
Caffeine
C8H10N4O2
Sulfur S8

13. Water H2O Compound Methane CH4 Carbon dioxide CO2 Oxygen O2 Element
Material
Chemical Formula
Element or compound?
Water
H2O
Compound
Methane
CH4
Carbon dioxide
CO2
Oxygen O2
Element
Chalk
CaCO3
Table salt
NaCl
Caffeine
C8H10N4O2
Sulfur S8

14. Water H2O Carbon dioxide CO2 Oxygen O2 Chalk CaCO3 Table salt NaCl
Material
Chemical Formula
How many Oxygen Atoms?
Water
H2O
Carbon dioxide
CO2
Oxygen O2
Chalk
CaCO3
Table salt
NaCl
Caffeine
C8H10N4O2

15. 1 2 3 Water H2O Carbon dioxide CO2 Oxygen O2 Chalk CaCO3 Table salt
Material
Chemical Formula
How many Oxygen Atoms?
Water
H2O 1
Carbon dioxide
CO2 2
Oxygen O2
Chalk
CaCO3 3
Table salt
NaCl
Caffeine
C8H10N4O2

16. CHALLENGE TIME – Using what you’ve learned, can you identify these molecules?
Hydrogen chloride HCl
Chlorine Cl2
Carbon dioxide CO2
Methane CH4
Draw a line between the molecule and its name.

17. Elements and Compounds

18. Mixtures
Element
Element
Molecule
Compound
Molecule
Atom
Can you find examples of atoms, molecules, elements and compounds in the mixtures above?