Question

ions quick check
when moving across a period from left to right in the periodic table (excluding transition elements) which trend occurs? (1 point)
valence electrons decrease by one
valence electrons increase by one
the energy levels increase by one
the energy levels decrease by one

Explanation:

In the periodic table, within a period (ex - transition elements), as we move from left to right, the atomic number increases by 1 for each successive element. Since the number of valence electrons is related to the group number and the group number increases by 1 from left to right across a period, the number of valence electrons increases by 1. Energy levels remain the same within a period as all elements in a period have the same principal quantum number for the outermost electrons.

Answer:

Valence electrons increase by one