What is the trend in atomic radius of the elements across Period 3 and why does this occur?
The atomic radius of the elements decreases from sodium to argon. This is because the number of protons increases (sodium has 11, argon has 18) so the nuclear charge increases. Therefore, the attraction between the positive nucleus and negative electrons in the outer shell increases, so the atomic radius (the distance between the nucleus and the outer shell) decreases. The electrons that are added from sodium to argon are all added into the same outer shell, so there is no difference in shielding.
CG
Related Chemistry A Level answers
All answers ▸What is the rate of a reaction and how can you determine it experimentally?
Calculate the number of moles in a sample of 113.47g of Ca(HCO3)2.
Back in 1950s, it was common to have as house cleaning items bleaching solution (containing sodium hypochlorite) and ammonia (used to remove, for example, hair dye stains). However, many people ended up in hospital after using them both, why?
Explain how the electron pair repulsion theory can be used to deduce the shape of, and the bond angle in, PF3