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Properties and trends across a period

Answer Text:
PROPERTIES AND TRENDS ACROSS A PERIOD
Introduction:
- A period is a vertical row of elements in the periodic table.
- Elements in the same period have same number of energy levels.
- There are 7 periods in the periodic table except for lanthanides and actinides which are not assigned periods.
- Periods 1 – 3 have fewer elements because they lack the d-block elements and have only the s-block elements and the p-block elements.
Note:
-s-block elements: group 1 and 2
-d-block elements: transitional elements
-p-block elements: groups III to VIII.
- To understand trends and properties across a typical period of the periodic table, we shall use period 3 as the reference.