Electronegativity is the ability of an atom to attract electrons in a chemical bond. Generally, elements with a small number of valence electrons tend to have lower electronegativities, especially if they also have larger atomic radii. This is because elements with fewer valence electrons are more likely to lose electrons (as they are closer to having a full octet) and thus do not attract electrons strongly.
Considering the options:
- A refers to an element with a small number of valence electrons and a small atomic radius, likely leading to higher electronegativity.
- B refers to an element with a large number of valence electrons and a small atomic radius, likely leading to higher electronegativity as well.
- C refers to an element with a small number of valence electrons and a large atomic radius, which suggests a lower ability to attract electrons, making it a candidate for low electronegativity.
- D refers to an element with a large number of valence electrons and a large atomic radius, which could also imply a lower electronegativity, but the large number of valence electrons could lead to greater attraction of electrons overall.
Therefore, the best choice for the lowest electronegativity would be C: an element with a small number of valence electrons and a large atomic radius.