Question

nomenclature & formulas quiz
version a
name:
period:

1. the elements in group 16 form a ____ charge when forming compounds.

a. -1 b. -2 c. +1 d. +2

1. the elements in group 2 form a ____ charge when forming compounds.

a. -1 b. -3 c. +1 d. +2

1. how many oxygen atoms must combine with lithium to form an ionic compound? (show your work)

a. 6 b. 1 c. 2 d. 3

1. what is the charge for cu in cuoh?

a. +1 b. -2 c. -1 d. +2

1. what is the prefix that represents the number six?

a. hepta b. nona c. penta d. hexa

1. what is the formula for magnesium oxide? (show your work)

a. mno b. mno₂ c. mgo d. mgo₂

1. what is the formula for barium nitride? (show your work)

a. ba₂n₃ b. ba₃n₂ c. ban d. ba₃n

1. what is the formula for tin(iv) selenide? (show your work)

a. snse b. snse₂ c. sn₂se d. snse₄

Explanation:

1. Group 16 Elements Charge

Group 16 elements (like oxygen) have 6 valence electrons. They gain 2 electrons to achieve a stable octet. So, they form a - 2 charge.

2. Group 2 Elements Charge

Group 2 elements (like magnesium) have 2 valence electrons. They lose 2 electrons to achieve a stable octet. So, they form a + 2 charge.

3. Lithium - Oxygen Compound

Lithium (Li) has a + 1 charge (\(Li^{+}\)), oxygen (O) has a - 2 charge (\(O^{2 -}\)). Using the criss - cross method:

$$\begin{align*} Li^{+}&\\ O^{2 -}& \end{align*}$$

We get \(Li_{2}O\), so 2 lithium atoms combine with 1 oxygen atom. But the question asks for the number of oxygen atoms combining with lithium. If we consider the ratio from the formula \(Li_{2}O\), for 2 Li atoms (total charge \(2\times(+1)=+2\)) and 1 O atom (charge - 2), the number of oxygen atoms per "unit" of the compound is 1.

4. Charge of Cu in CuOH

The hydroxide ion (\(OH^{-}\)) has a - 1 charge. Let the charge of Cu be \(x\). In the compound \(CuOH\), using the charge balance: \(x+( - 1)=0\) (since the compound is neutral). Solving for \(x\), we get \(x = + 1\).

5. Prefix for Six

• Hepta - represents 7.
• Nona - represents 9.
• Penta - represents 5.
• Hexa - represents 6.

6. Magnesium Oxide Formula

Magnesium (Mg) has a + 2 charge (\(Mg^{2+}\)), oxygen (O) has a - 2 charge (\(O^{2 -}\)). Using the criss - cross method (dividing by the greatest common divisor of 2 and 2 which is 2), we get \(MgO\).

7. Barium Nitride Formula

Barium (Ba) has a + 2 charge (\(Ba^{2+}\)), nitride (\(N^{3 -}\)). Using the criss - cross method:

$$\begin{align*} Ba^{2+}&\\ N^{3 -}& \end{align*}$$

We get \(Ba_{3}N_{2}\) (since \(2\times3 = 3\times2\) for charge balance: \(3\times(+2)+2\times(-3)=0\)).

8. Tin(IV) Selenide Formula

Tin(IV) (\(Sn^{4+}\)), selenide (\(Se^{2 -}\)). Using the criss - cross method:

$$\begin{align*} Sn^{4+}&\\ Se^{2 -}& \end{align*}$$

Dividing by the greatest common divisor of 4 and 2 (which is 2), we get \(SnSe_{2}\) (\(4\times1+2\times(- 2)=0\)).

Answer:

1. b. - 2
2. d. + 2
3. b. 1
4. a. + 1
5. d. hexa
6. c. MgO
7. b. \(Ba_{3}N_{2}\)
8. b. \(SnSe_{2}\)