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GCSE Science Booster Tutor: Trends within the Periodic Table. Group 1.

A quick boost to your understanding of the trends within Group 1 of the periodic table.

· GCSE Science Notes

Studying Group 1 of the Periodic Table is probably one of the most exciting topics of GCSE science/chemistry because this happens:


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This is the element caesium reacting with water. It is explosive.

Caesium is an element found in Group 1 of the periodic table. How does it compare with the other elements of Group 1?

First, let us recap the purpose of the periodic table.

The modern periodic table groups all of the known elements. Elements are pure substances found all around us. They are made up of atoms of that element.

There are over 100 known elements and the periodic table arranges them according to their properties.

There are vertical columns of elements called GROUPS and rows of elements called PERIODS. The elements are arranged in these Groups and Periods because of similarities in their physical and chemical properties.


All Group 1 elements contain atoms with 1 electron in their outer shell.


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Group 1 elements are called Alkali Metals and are very reactive. Alkali metals are so reactive that they have to be stored in oil. Oil stops air getting to them so that they cannot react so readily with oxygen. 

Their high reactivity is due to the 1 electron in their outer shell. The atoms are very keen to lose this electron to other atoms of elements to form positive ions.

They all react vigorously with water to form the metal hydroxide and hydrogen gas.

For example, lithium:

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From the images above you can see that as you move down the group the metals become more reactive. This occurs because as you move down the group the electron in the outer shell becomes further away from the nucleus, causing the electrostatic forces to weaken. The negative electron now has less pull from the positive nucleus and can readily be pulled towards another atom or atoms.

After potassium comes rubidium and this is where the reactions start to becoame explosive so you are unlikely to witness these in your classroom.


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Alkali metals are soft metals. They can be cut with a knife (like cheese).


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Their softness also increases as you move down the group. The melting and boiling point of the alkali metals decrease as you go down the group.

This blog is written in conjunction with the Combi Classroom GCSE Science Study Books. The moving images are here to create a visual picture in your mind to help with the revsion and understanding process.

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