Valence change across periods

Recall that the size of an atom increases in any group of elements as you go down the colrunn because the valence electrons are found in energy levels farther and farther from the nucleus. But how does atomic radius change across a period from left to right Take Period 2 as an example. 

The Lewis dot diagrams for these elements illustrate how valence electrons change from element to element across a row on the periodic table. 

More generally, the change in valence across the second and third periods shows a smooth increase from 1 to 4, followed by an equally uniform decrease down to 0 for the noble gases. 

The electron arrangements of atoms are an important factor in the physical and chemical properties of the elements. Now we will look at the valence electrons in atoms, the trends in atomic size, ionization energy, and metallic character. Known as periodic properties, there is a pattern of regular change going across a period, and then the trend is repeated again in each successive period. 

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