Unit 3 - Atoms and the Periodic Table
This unit looks at the ways elements are grouped together, what elements are made up of and the structure of an atom.
Gathering Elements Together
There are over 100 different elements. Some are shiny - like silver and gold - some are gases - like hydrogen and oxygen - and some are colour, like iodine and sulphur. When we are faced with a wide variety of things in common we often try to gather those which have something in common. This is called classification.
An example of classification in the periodic table could be separating the elements apart depending on whether they are naturally occurring or made by scientists.
Naturally Occurring: Titanium, Copper, Zinc, Hafnium and Niobium.
Made by Scientists: Neptunium, Curium, Fermium and Nobelium.
Another example of classification in the periodic table is the way in which the non-metals are on the right side and the metals are on the left side.
The Physical State of a Substance
The state of a substance whether solid, liquid or gas, can be determined using the following rules :-
- Assume that room temperature is approximately 20'c.
- If 20'c is below the Melting Point of the substance, it is a solid at room temperature ( Solid = Melting Point < Room Temperature).
- If 20'c is between the Melting Point and Boiling Point of the substance, it is a liquid at room temperature ( Liquid = Melting Point <Room Temperature> Boiling Point ).
- If 20'c is above the Boiling Point of the substance it is a gas at room temperature ( Gas = Room Temperature > Boiling Point).
Families of Elements
The name given to the modern-day arrangement of the elements is called the periodic table.
The non-metals are found on the right side of the periodic table.
The metals are found on the left side of the periodic table.
The transition metals are metals in the centre of the periodic table.
A 'group' in the periodic table is a vertical family of elements with similar properties.
The group known as 'the alkali metals' are group 1 of the periodic table.
The group known as 'the halogens' are group 7 of the periodic table.
The group known as the 'noble gases' are group 8 of the periodic table.
Examples of chemical and physical similarities of elements in Group 1 are: they are all soft metals which are shiny and silver, and they all react violently with water.
Examples of chemical and physical similarities of elements in Group 2 are: they are all shiny and silver coloured, and they all react with acids and steam.
Alkali metals are kept under oil, this is to prevent them from reacting with moisture in the air ( as alkali metals react violently with water).
The noble gases are often referred to as the 'inert gases' as they are very unreactive.
Some uses of the noble gases include: Helium - weather balloons, and neon lights.
The similarity of the elements…