1. Characteristics of Substances
Elements, compounds, mixtures

2. Atoms
Smallest piece

3. Elements Red block Blue block Each type of Atom is called an Element
LEGO
WORLD
Different colours ,sizes and shapes
Different properties

4. Elements are substances made up of only one type of atom.
Example:

5. Molecules A molecule is made up of two or more atoms chemically combined.
Water (H2O)

6. Chemical Reaction
Element or Molecules combining together = > Chemical Reaction O H
Water (H2O) O H +

7. Aristotle's Elements
Earth Air Fire Water

8. What is an Element ? Everything in the Universe is made from Elements
There are over 100 elements
The most common element in the Universe is Hydrogen
The Term “Element” was introduced by an Irish scientist Robert Boyle –
“Simple Substance”

9. Element
An Element is a substance that cannot be split up into simpler substances by chemical means.

10. Common Elements

11. Oxygen – Most abundant Element in Earths Crust

12. What is this ? Element Percentage Oxygen 65% Carbon 18% Hydrogen 10%
Nitrogen 3%
Calcium
1.5%
Phosphorus
1.0%
Potassium
0.35%
Sulfur
0.25%
Sodium
0.15%
Magnesium
0.05%
Copper, Zinc, Selenium, Molybdenum, Fluorine, Chlorine, Iodine, Manganese, Cobalt, Iron
0.70%
Lithium, Strontium, Aluminium, Silicon, Lead, Vanadium, Arsenic, Bromine
Trace amounts
Reference: H. A. Harper, V. W. Rodwell, P. A. Mayes, Review of Physiological Chemistry, 16th ed., Lange Medical Publications, Los Altos, California 1977.
Most of the human body is made up of water, H2O, with cells consisting of 65-90% water by weight. Therefore, it isn't surprising that most of a human body's mass is oxygen. Carbon, the basic unit for organic molecules, comes in second. 99% of the mass of the human body is made up of just six elements: oxygen, carbon, hydrogen, nitrogen, calcium, and phosphorus.

13. Periodic Table of Elements

14. Symbols Each Element is given a unique Symbol
First letter of its name (H, C, O)
First two letters of its name (Si, Ne, Li)
Taken from its Latin name (Pb, Fe, Au)

15. Metals METAL SYMBOL Copper Cu Zinc Zn Aluminium Al Iron Fe Silver Ag
Gold Au

16. Non Metals NON METAL SYMBOL Carbon C Oxygen O Sulphur S Hydrogen H
Nitrogen N

17. Atom
An Atom is the smallest particle of an Element that still retains the properties of that element.

18. What’s inside the atom?

19. Compounds
A Compound is a substance that is made up of two ore more different elements combined chemically together.

20. Compounds H C O H H
Water (H2O)
Methane (CH4) C O
Carbon Dioxide (CO2)

21. Compound ? O O
Oxygen (O2) H H
Hydrogen (H2)

22. When a compound is formed during a chemical reaction its properties differ from those of the elements from which it is made

23. Mixtures
A mixture consists of two or more different substances mingled together but not chemically combined.
Examples: Sea – water and salt
Air – nitrogen, oxygen …
Soil – sand, clay, humus …

24. Mixture vs Compound
MIXTURE
COMPOUND

25. Mixture
Compound
The amounts of the substances in the mixture can vary.
The elements in a compound are always present in the same fixed proportion.
A mixture contains two or more substances
A compound is a single substance.
The properties of a mixture are similar to those of the substances in a mixture.
The properties of a compound are different to those of the elements which reacted to form it.
There are practically no energy changes when a mixture is made
Heat is usually given out or taken in when a compound is formed.
It is usually easy to separate the components of a mixture.
It is usually difficult to separate the components of a compound.