1. Natural Sciences Grade 7
Term 2: Matter & Materials
Introduction to the Periodic Table of Elements

2. Topic 4 Introduction to the Periodic Table of Elements
Arrangement of elements on the Periodic Table
Natural Sciences - Grade 7

3. The Periodic Table of Elements
Dmitri Mendeleev was a Russian chemist in 1860’s.
In 1872, he arranged the elements in a table format according to their properties.
His table was the first to gain scientific credibility, but it was not the first periodic table that organized the elements according to its periodic properties).
Image of Dmitri Mendeleev
An element is a pure substance that cannot be broken down further
Mendeleev's table arranged the elements in order of increasing atomic mass.
Whenever new data becomes available, the International Union of Pure Applied Chemistry, IUPAC, revises the periodic table
Natural Sciences - Grade 7

4. The Periodic Table of Elements
a large grid of every element that exists. 
a classification system (ordering and grouping) of the elements which make up all the matter (everything around us that we can see and touch) and materials in our world in a very useful and logical manner
the columns of the Periodic Table are called groups and
the rows are called periods
An element is a pure substance that cannot be broken down further.
Mendeleev's table arranged the elements in order of increasing atomic weight.
The modern table orders the elements by increasing atomic number.
The first artificially made element was Technetium.
Whenever new data becomes available, the International Union of Pure Applied Chemistry, IUPAC, revises the periodic table.
Natural Sciences - Grade 7

5. The Periodic Table of Elements
Each element’s block has two numbers, the atomic number and mass number
Atomic mass
The modern table orders the elements by increasing atomic number.
The first artificially made element was Technetium
Atomic number
Natural Sciences - Grade 7

6. The Periodic Table of Elements
The chemical symbol of an element always starts with a capital letter and if there is a second letter, it is a lower case letter e.g. C, Cu, N and Ne.
90 elements on the periodic table occur in nature (the others are man-made elements).
Most elements on the periodic table are metals (groups of metals: lanthanides, actinides, alkaline earths, alkali, basic and transition).
E.g. Gold 
The modern table orders the elements by increasing atomic number.
Natural Sciences - Grade 7

7. Grouping and ordering of the elements
The elements of the Periodic Table are arranged into the following three main categories:
Metals; Non-metals and Semi-metals.
A step line divides the metals from the non-metals.
Natural Sciences - Grade 7

8. Grouping and ordering of the elements
Metals
Coloured in different shades of blue and arranged on the left side and in the middle of the Periodic table.
Natural Sciences - Grade 7

9. Grouping and ordering of the elements
Non-metals
Coloured in white, red and black; are arranged on the Periodic table’s far right-hand side (except for Hydrogen which is on the top left corner).
Natural Sciences - Grade 7

10. Grouping and ordering of the elements
Semi-metals
Coloured in yellow and found on either side of the
zigzag step line that separates metals and non-
metals.
Natural Sciences - Grade 7

11. The names and symbols of the elements
Each element has its own name, symbol, atomic number and position on the Periodic Table.
Certain symbols match the names of the elements (e.g. He = Helium; H= Hydrogen; N= Nitrogen; etc.).
Certain symbols match old Latin/Greek names that are no longer used (e.g. Sodium’s Latin name is natrium; the symbol for sodium = Na. The symbol for silver is Ag from the Latin name argentum.
Natural Sciences - Grade 7

12. Natural Sciences - Grade 7
Uses of elements
Element
Uses
Oxygen (O)
The air we breathe.
Nitrogen (N) and
Two main gases in the air. Air contain about 78% nitrogen and 21% oxygen.
Platinum (Pt)
To make jewellery; in the production of catalytic converters (reduce the harmful gases that cars emit; important for environmental protection).
Argon (Ar)
Gas in the air that is used to preserve food products, e.g. potato chips.
Many elements on the Periodic Table might sound new, but we have been using some as part of our daily lives.
Natural Sciences - Grade 7

13. Natural Sciences - Grade 7
Uses of elements
Element
Uses
Aluminium (Al)
To manufacture cans of fizzy drinks, window and door frames, etc.
Lithium (Li)
In rechargeable batteries.
Sulphur (S) and Phosphorus (P)
Used in fertilizers for plants.
Silicon (Si)
To manufacture microchips in electronic devices.
Copper (Cu)
In electrical devices and in wiring (good conductor of electricity).
Many elements on the Periodic Table might sound new, but we have been using some as part of our daily lives
Natural Sciences - Grade 7

14. Uses of elements: examples
Pictures - Top row:
Breathe in oxygen
Sulfur and Phosphorous in matches
Copper in wiring
Lithium in rechargeable battery
Pictures – bottom row:
Silicon in microchip
Aluminium cans
Platinum jewellery
Natural Sciences - Grade 7