Which is more ionic LiF or NaF and why

Look up the electronegativity and subtract. The larger difference means a more ionic bond.

To determine which compound is more ionic, LiF or NaF, we need to analyze factors that influence ionic character. Ionic character is determined by the difference in electronegativity between the two atoms in a compound.

Electronegativity is a measure of an atom's ability to attract electrons towards itself in a covalent bond. It increases as we move across a period from left to right on the periodic table.

In this case, we need to compare the electronegativities of lithium (Li) and sodium (Na) with fluorine (F). Lithium is in the first period and sodium is in the third period of the periodic table. Fluorine is in the second period. Since electronegativity increases across a period, the electronegativity of fluorine is higher than that of both lithium and sodium.

Now, we can look at the electronegativity difference between the metal (Li or Na) and the non-metal (F). The greater the difference, the more polar the bond is, indicating a more ionic compound.

The electronegativity difference between Li and F is 1.0 (3.0 - 2.0), while between Na and F, it is 0.9 (3.0 - 2.1). The larger the difference, the more ionic the compound.

Based on the electronegativity difference, we can conclude that LiF is more ionic than NaF. This is because the electronegativity difference between lithium and fluorine (1.0) is greater than the electronegativity difference between sodium and fluorine (0.9).