Introduction to Groups in the Periodic Table
The Periodic Table is not just a list of elements — it is organised so that elements with similar properties are grouped together in columns, called groups. This means that by knowing one element in a group, you can make predictions about the others!
In this subtopic, we focus on four key groups:
- Group 1 — the Alkali Metals
- Group 2 — the Alkaline Earth Metals
- Group 17 — the Halogens
- Group 18 — the Noble Gases
Each of these groups has its own set of characteristic properties, and the elements within each group share striking similarities.
Think of the groups in the Periodic Table like families. Just as family members share certain features — a similar nose, height, or personality — elements in the same group share chemical and physical "family traits."
Group 1 — The Alkali Metals
A metal found in Group 1 of the Periodic Table. Alkali metals are soft, low-density, highly reactive metals that react with water to form alkaline solutions.
The alkali metals include lithium (Li), sodium (Na), potassium (K), and other elements further down the group. Despite being metals, they are quite different from the metals we typically think of (like iron or copper).
Key properties of alkali metals:
- They are soft — you can cut them with a knife
- They have low density — lithium, sodium and potassium are all less dense than water
- They are highly reactive, especially with water
- They do not exist in their pure form in nature because they react so readily with things around them
- They have relatively low melting points compared to most metals
Sodium is so reactive that it must be stored under oil to prevent it from reacting with oxygen and moisture in the air. You would never find a chunk of pure sodium just lying around in nature!
10 more sections in this topic
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