Final answer:
The collective term for the elements on the left side of the periodic table is 'main group elements,' including alkali and alkaline earth metals. They're first when naming compounds due to their placement and chemical properties.
Step-by-step explanation:
The collective term for the elements on the left side of the periodic table are main group elements, which includes the alkali metals of Group 1 and the alkaline earth metals of Group 2. These elements exhibit similar chemical properties and reactive behaviors. When it comes to chemical compounds, elements that are on the left tend to be named first due to convention, as seen in examples like NaCl (sodium chloride), KBr (potassium bromide), and FeS (iron sulfide).
These main group elements are divided further into the alkali metals, which form compounds containing one atom of the element and one atom of hydrogen, and the alkaline earth metals, forming compounds with one atom of the element and two atoms of hydrogen. The periodic table arranges these elements into groups and periods based on their atomic number and similar chemical properties, which helps predict their behaviors in reactions and compounds.