Chapter 3, Problem 1P

3-17 Answer true or false.

(a) The octet rule refers to the chemical bonding patterns of the first eight elements of the Periodic Table.

(b) The octet rule refers to the tendency of certain elements to react in such a way that they achieve an outer shell of eight valence electrons.

(c) In gaining electrons, an atom becomes a positively charged ion called a cation.

(d) When an atom forms an ion, only the number of valence electrons changes; the number of protons and neutrons in the nucleus does not change.

(e) In forming ions, Group 2A elements typically lose two electrons to become cations with a charge of + 2.

(f) In forming an ion, a sodium atom (1s²2s²2p⁶3s¹) completes its valence shell by adding one electron to fill its 3s shell (1s² 2s² 2p⁶3s²).

(g) The elements of Group 6A typically react by accepting two electrons to become anions with a charge of −2.

(h) With the exception of hydrogen, the octet rule applies to all elements in periods 1,2, and 3.

(i) Atoms and the ions derived from them have very similar physical and chemical properties.

Interpretation Introduction

Interpretation: true or false:

The octet rule refers to the chemical bonding patterns of the first eight elements of the periodic table.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

False

Explanation of Solution

The octet refers to the tendency of atoms to prefer to achieve eight valence electrons in the outer shell. This rule is common among atoms of group 1A-7A.

Interpretation Introduction

Interpretation: true or false:

The octet rule refers to the tendency of certain elements to react in such a way that they achieve an outer shell of eight valence electrons.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

True

Explanation of Solution

An atom gains or loses electrons in a chemical reaction to achieve eight electrons in the outer shell. This tendency of atoms to achieve eight electrons is called as octet rule and is followed by the atoms of Group 1A-7A.

Interpretation Introduction

Interpretation: true or false:

In gaining electrons, an atom becomes a positively charged ion called a cation.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

False

Explanation of Solution

When an atom gains electron, the number of electrons in an atom increases when compared to the number of protons in the nucleus. Thus, it forms a negatively charged ion called an anion.

Interpretation Introduction

Interpretation: true or false:

When an atom forms an ion, only the number of valence electrons changes, the number of protons and neutrons in the nucleus does not change.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

True.

Explanation of Solution

An atom gains or loses electrons to form ions. When an atom gains electrons, the number of electrons in an atom increases when compared to the number of proton in the nucleus. Thus it forms a negatively charged ion called an anion. When an atom loses electrons, the number of electrons in an atom decreases when compared to the number of protons in the nucleus. Thus, it forms positively charged ion called a cation.

Thus, the formation of ion the number of valence electrons changes, but the number of protons and neutrons remains.

Interpretation Introduction

Interpretation: true or false:

In forming ions, Group 2A elements typically lose two electrons to become cation with a charge of +2.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

True.

Explanation of Solution

The group 2A elements have 2 electrons in their outermost shell. Therefore, by donating two electrons, these elements attain the stable electronic configuration of the nearest noble gas in relation to its atomic number.

Interpretation Introduction

Interpretation: true or false:

In forming an ion, a sodium atom (1s²2s2p⁶3s¹) completes its valence shell by adding one electron to fill its 3s shell (1s²2s2p⁶3s²).

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

False.

Explanation of Solution

The electronic configuration of sodium is (Na) is

1s²2s2p⁶3s¹

The sodium atom loses one electron and then its electronic configuration is,

1s²2s2p⁶

And then it attains noble gas configuration.

Interpretation Introduction

Interpretation: true or false:

The Group 6A elements have 6 electrons in their outermost shell. To attain the stable electron configuration of the nearest noble gas, group 6A elements accepts 2 electrons and acquires a -2 charge.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

True.

Explanation of Solution

The group 6A elements belong to oxygen family. Taking an example of oxygen atom, the atomic number is 8 thus, the electronic configuration is $1s^{2}2s^{2}2p^4$ . In the outermost shell, it has 6 electrons thus, it can gain 2 electrons to get -2 charge and form an anion.

Interpretation Introduction

Interpretation: true or false:

With the exception of hydrogen, the octet rule applies to all elements in periods 1, 2 and 3.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

False.

Explanation of Solution

The elements of the first period have only one valence shell that is 1s orbital. Hence the atoms of these elements can hold a maximum of two electrons.

The elements of second period have two valence shells that are 2s and 2p orbitals. Thus, the valence shells of the second period elements can hold a maximum of eight electrons.

The elements of third period have three valence shells that are 3s, 3p, and 3d orbitals. Therefore these elements can hold more than eight electrons. Thus, third period elements do not obey the octet rule.

Hence, the octet rule applies to elements of the second period.

Interpretation Introduction

Interpretation: true or false:

Atoms and the ions derived from them have very similar physical and chemical properties.

Concept introduction:

The octet rule alludes to the atom’s tendency to contain eight electrons in the valence shell. When any atom contains less than eight electrons, they would tend to react as well as form the compounds which are more stable. An octet resembles to the electronic configuration which are ending with s²p⁶.

Answer to Problem 1P

False.

Explanation of Solution

The ions derived from their atoms can have different physical and chemical properties. For example, if sodium metal is placed with kerosene, it explodes when it comes in contact with water. Chlorine is toxic gas, but on the other hand, a sodium ion and a chlorine ion combine to form of salt, which is consumed in our daily life.