Question

Complete the table by filling in the formula for the ionic compound formed by each pair of cations and anions, as shown for the first pair. ion k+ nh+4 mg2+ fe3+ cl− kcl oh− co2−3 po3−4

Answer 1

In chemistry, the elements that exist with electrical charges are called ions. These ions can carry a positive charge, for which they are called cations, or a negative charge, for which they are called anions. These ions carry an electric charge because they do not conform to the stable number of electrons of their neutral atom. Because of this, they carry excess electrons for cations, and a lack of electrons for the anions.

When cations and anions form together such that there is a complete transfer of electrons so that each ion would be neutral, an ionic bond is formed. If you write the reaction, the superscripts and subscripts would just cross-multiply. If the cation is A⁺ᵃ, and the anion is B⁻ˣ, then the ionic compound would then be AₓBₐ. Of x=a, then they will cancel out which will yield AB. Therefore, the ionic compound for each pair of ions are:

NH₄⁺ + OH⁻ = NH₄OH
Mg²⁺ + CO₃²⁻ = MgCO₃
Fe³⁺ + PO₃⁴⁻ = Fe₄(PO₃)₃

Answer 2

The ionic compounds formed are: $NH_{4}OH, \ MgCO_{3}, \ and \ FePO_{4}$.

FURTHER EXPLANATION

Ionic compounds are made up of ion pairs (cation - anion).

Ions

Ions are atoms that gained or lost electrons and have become charged. Atoms become positively charged when they lose one or more electrons and negatively charged when they gain extra electrons. Cations are positively charged ions while anions are negatively charged.  

Ions may also be monatomic or polyatomic. Monatomic ions are made up of only one element. A polyatomic ion is a group of elements covalently bonded to each other but the entire unit is charged.

Formulas of Ionic Compounds

Ionic compounds are neutral substances. They have a net charge of zero resulting from the balanced charges of the cations and anions. With this in mind, when writing the chemical formula of ionic compounds, the total positive charge due to the cation must be equal to the total negative charge due to the anion and their sum should be zero.

Criss-cross Method

The steps in writing the chemical formula are as follows with an example for $Li^{+} \ and \ O^{2-}:$

• Write the chemical symbol of the cation but do not include the charge (or superscript). Beside it write the symbol for the anion without the charge.

        Ex: Li O

• Beside the cation symbol, write as a subscript, the numeric value of the charge of the anion. Do not include the sign.

        Ex. Since the charge of the anion O2- is -2, write 2 as the

        subscript of  Li : $Li_{2}O$

• As a subscript beside the anion, write the numeric value of the charge of the cation. Do not include the sign.

         Ex. Since the charge of Li+ is +1, the subscript beside O    

         will be 1.  When the subscript is supposed to be 1, it is not

         written but simply implied ( by not putting any subscript at

         all):  $Li_{2}O$

• Check if the net charge of the compound is zero by getting the sum of the charge of each ion multiplied by its subscript. If not, double check the subscripts.

        Net charge = 2(+1) + (-2) = 0.

1. $NH_{4}^{+} \ and \ OH^{-}$

Since the polyatomic cation has a +1 charge and the polyatomic anion has a -1 charge, having one of each group balances the charges. Therefore, the formula is $NH_{4}OH$.

2. $Mg^{2+} \ and \ CO_{3}^{2-}$

The cation has a charge of +2 and the carbonate anion has a charge of -2. The net charge will be zero if one of each is in the formula unit$MgCO_{3}$.

3. $Fe^{3+} \ and \ PO_{4}^{3-}$

The cation has a +3 charge and the phosphate ion has a -3 charge. Their charges cancel when one cation and one anion is in the formula unit which is $FePO_4$.

LEARN MORE

• ion formation brainly.com/question/6177640
• covalent compound brainly.com/question/8711546
• naming ionic compounds brainly.com/question/7193259

Keywords: chemical formula, ions, ionic compound