The periodic table is arranged by various patterns Identify two patterns and give examples of both patterns
Two patterns in the periodic table are the increasing atomic number pattern and the periodicity of chemical properties pattern.
1. Increasing Atomic Number Pattern:
The periodic table is arranged in order of increasing atomic number. This means that elements with lower atomic numbers are placed on the left side of the table, while elements with higher atomic numbers are placed on the right side. For example:
- Hydrogen (atomic number 1) is the first element on the periodic table.
- Helium (atomic number 2) is the second element, right after hydrogen.
- Lithium (atomic number 3) is the third element, following helium.
2. Periodicity of Chemical Properties Pattern:
Elements in the periodic table are grouped based on their chemical properties, and these properties tend to repeat or show periodicity across each period (horizontal rows) and group (vertical columns) of the table. For example:
- Group 1 elements (alkali metals) are located in the first column and share similar chemical properties. They are all highly reactive metals that readily lose one electron to form a +1 ion. Examples include lithium, sodium, and potassium.
- Group 17 elements (halogens) are located in the seventeenth column and also share similar chemical properties. They are all highly reactive non-metals that readily gain one electron to form a -1 ion. Examples include fluorine, chlorine, and bromine.