What happens to the atomic radius as you move across a period from left to right?

1. Moving across a period adds protons to the nucleus while filling the same energy level. 2. The stronger positive pull draws the electron cloud in tighter. 3. The atomic radius therefore decreases across a period. 4. Ionisation energy and electronegativity move the other way and increase across a period. 5. Down a group the pattern flips, since the atomic radius increases. _Source: Siyavula Physical Sciences Grade 10 (Everything Science, CC BY 4.0), Chapter 5: The periodic table_