Chapter 22, Problem 1E

Give the formula of the stable fluride by Li, Be, B , C, N, and O. For these fluorides, describes the varition in the bonding that occurs as we move from left to right across the period.

Interpretation Introduction

Interpretation:

For each of the elements- $Li,Be,B,C,N\text{ and }O$, the formula for the stable fluoride formed is to be given. Then the variation in bonding that occurs when we move from left to right across the period is to be described.

Concept introduction:

• Fluorine forms a variety of chemical compounds but it always adopt an oxidation state of (-1).
• Electronegativity of elements increases as we move from left to right in a period.
• Bonding is generally of two types- ionic and covalent.

In ionic bonding, atoms lose or gain electrons to form ions and these are ions that are bonded through forces of attraction.

In covalent bonding, a covalent bond is formed between the atoms by sharing of valence electrons.

Answer to Problem 1E

Formula for each of the element for the stable fluorides ( $F^{-}$ ) is-

$Li$	$LiF$
$Be$	$Be{F}_2$
$B$	$B{F}_3$
$C$	$C{F}_4$
$N$	$N{F}_3$
$O$	$O{F}_2$

And

As we move from left to right across a periodic table, the bonding shifts from ionic boning to covalent bonding.

Explanation of Solution

Generally,

Metal + non-metal →Ionic compounds

Non-metal +non-metal →Covalent compounds

Thus, Fluorine is a non-metal and it forms ionic compound with a metal ( $Li,Be$ ) and covalent compound with non-metals ( $B,C,N,O$ ).

Therefore, formula for each of the element for the fluorides ( $F^{-}$ ) is-

$Li$	$LiF$
$Be$	$Be{F}_2$
$B$	$B{F}_3$
$C$	$C{F}_4$
$N$	$N{F}_3$
$O$	$O{F}_2$

As we move from left to right across a periodic table, the metallic character of the element decreases. Hence, the bonding shifts from ionic boning to covalent bonding as it is not easier to take away the electrons from the non-metals to form ions.

Conclusion

$Li$	$LiF$
$Be$	$Be{F}_2$
$B$	$B{F}_3$
$C$	$C{F}_4$
$N$	$N{F}_3$
$O$	$O{F}_2$

$LiF$, $Be{F}_2$ are ionic compounds and $B{F}_3$, $C{F}_4$, $N{F}_3$, $O{F}_2$ are covalent compounds.