Question 1

A ClO₂^-ion has _____ valence electrons.

Accepted Answer

- There are 2 Cl (chlorine) atoms, each with 7 valence electrons, giving a total of 14 valence electrons.
- There is 1 O (oxygen) atom, with 6 valence electrons.
- There is 1 S (sulfur) atom, with 6 valence electrons.
- There are 1 P (phosphorus) atom, with 5 valence electrons.
- There are 2 U (unknown) atoms, each with an unknown number of valence electrons.

Therefore, the total number of valence electrons is 14 + 6 + 6 + 5 + 2x (unknown). Simplifying this expression gives 31 + 2x.

To determine the value of x, we can use the fact that the ion has a charge of -1. This means that there must be one more electron than the total number of protons in the ion.

- The Cl atoms each have 17 protons (from their atomic number).
- The O atom has 8 protons.
- The S atom has 16 protons.
- The P atom has 15 protons.
- The U atoms have an unknown number of protons (which could be different from each other).

Adding these together gives a total of 73 protons. Since the ion has a charge of -1, it must have 74 electrons.

So we can set up an equation:

31 + 2x = 74

Solving for x gives:

x = 21.5

However, valence electrons must be whole numbers, so we round x up to 22.

Therefore, there are a total of 14 + 6 + 6 + 5 + 2(22) = 74 valence electrons in this ion.

The best choice is C) 20, since it is the only option that corresponds to a multiple of 8 (the number of valence electrons in the oxygen and sulfur atoms).

Question 2

Which Lewis structure,although acceptable,LEAST describes the carbonate ion?

Accepted Answer

B

Question 3

Which compound has an expanded octet around the central atom?

Accepted Answer

C has an expanded octet around the central atom (S) because it has six electron pairs (four bonded pairs and two lone pairs) surrounding the central atom, which exceeds the octet rule for elements beyond the second row.

Question 4

What is the formal charge on the nitrogen atom in this structure?

Accepted Answer

The answer of What is the formal charge on the...

Question 5

Ozone has the formula O₃.Which statement is CORRECT concerning ozone?

Accepted Answer

In ozone (O3), the molecule is structured with one oxygen atom having a double bond with another oxygen atom (neutral), and the third oxygen atom is connected by a single bond to one of the doubly bonded oxygen atoms and has a lone pair, resulting in one oxygen atom having a +1 formal charge (the one with the single bond) and another having a -1 formal charge (the one with the lone pair), while the third (doubly bonded) oxygen atom is neutral.

Question 6

How many atoms in this molecule have a tetrahedral geometry?

Accepted Answer

The answer of How many atoms in this molecule have...

Question 7

How many atoms in this molecule have a trigonal planar geometry?

Accepted Answer

The answer of How many atoms in this molecule have...

Question 8

What is the electronic geometry around the central atom in CO₂?

Accepted Answer

The answer of What is the electronic geometry around the...

Question 9

The Lewis structure of the cyanide ion is shown here.How many valence electrons are in this ion?

Accepted Answer

The cyanide ion has a total of 10 valence electrons. To determine this, we count the number of valence electrons for each atom in the ion. Carbon has 4 valence electrons and nitrogen has 5, giving a total of 9. Additionally, there is 1 extra electron to account for the negative charge of the ion, bringing the total to 10.

Question 10

Which molecule does NOT have a lone pair on the central atom?

Accepted Answer

CO₂ has a linear structure with no lone pairs on the central carbon atom, as it forms double bonds with each oxygen atom.

Question 11

Which statement is CORRECT concerning the cyanide ion?

Accepted Answer

The cyanide ion has a linear geometry, with the carbon and nitrogen atoms arranged in a straight line. Therefore, option C is the correct statement. The other options are incorrect as they describe either a tetrahedral or trigonal planar geometry, neither of which is present in the cyanide ion.

Question 12

A phosphorus atom with four bonds has a charge of:

Accepted Answer

A phosphorus atom typically forms three bonds in a neutral state. If it forms four bonds, it has one more bond than usual, resulting in a positive charge of +1.

Question 13

What is the formal charge on the oxygen atom in this structure?

Accepted Answer

The answer of What is the formal charge on the...

Question 14

In this Lewis structure,which atom does NOT have a complete valence?

Accepted Answer

In the Lewis structure, boron (B) only has six valence electrons and therefore does not have a complete valence shell. H has one valence electron, C has four, and Cl has seven, all of which complete their valence shell in the Lewis structure.

Question 15

Which Lewis structure BEST describes the carbonate ion?

Accepted Answer

The answer of Which Lewis structure BEST describes the carbonate...

Question 16

Which compound has 24 valence electrons?

Accepted Answer

Compound A (CS2) has 24 valence electrons: Carbon (C) has 4 valence electrons, and each Sulfur (S) atom has 6 valence electrons. Since there are two Sulfur atoms, the total is 4 + (6*2) = 16 for the Sulfur atoms alone, adding up to 24 valence electrons in total.

Question 17

A neutral carbon atom has _____ valence electrons.

Accepted Answer

Carbon has 4 valence electrons, which are the electrons in the outermost energy level. Since it is a neutral atom, the number of valence electrons is equal to the number of electrons in the atom.

Question 18

A oxygen atom with one bond and three lone pairs has a charge of:

Accepted Answer

An oxygen atom with one bond and three lone pairs has a total of 8 valence electrons, which is the stable electron configuration of a noble gas (neon). However, since oxygen has 6 valence electrons in its neutral state, it needs to gain two electrons to achieve this stable configuration. When it forms a bond with another atom, it shares one electron from its valence shell, leaving it with 7 electrons. Since it still needs one more electron to achieve the stable configuration, it will attract an additional electron to form a negative ion. Therefore, an oxygen atom with one bond and three lone pairs has a charge of -1.

Question 19

A neutral sulfur atom has _____ valence electrons.

Accepted Answer

Sulfur has six valence electrons, as it is in group 16 on the periodic table and has an electron configuration of [Ne] 3s2 3p4.

Question 20

What is the electronic geometry around the oxygen atoms in CO₂?

Accepted Answer