Chapter 5, Problem 51E

Interpretation Introduction

(a)

Interpretation:

The terms, atom and subatomic particle are to be distinguished precisely.

Concept introduction:

Dalton realized that the Law of Conservation of Mass, the Law of Definite Composition and the Law of Multiple Proportions could be explained if matter was considered to be made up of indivisible particles called atoms.

Answer to Problem 51E

Matter is made up of atom while atoms are made up of subatomic particles.

Explanation of Solution

Matter is made up of basic units termed as atoms. Subatomic particles are those particles whose size is smaller than the atom. Neutrons, electrons and protons are present within an atom. Therefore, all of them are subatomic particles. Therefore, an atom is made up of subatomic particles.

Conclusion

Matter consists of atoms while atom consists of subatomic particles.

Interpretation Introduction

(b)

Interpretation:

The terms, electron, proton, and neutron are to be distinguished precisely.

Concept introduction:

An atom is made up of three subatomic particles-neutrons, protons, and electrons. Neutron and protons are present in the nucleus of the atom, whereas electrons are revolving outside the nucleus in an atom. In a neutral atom number of electrons and the number of protons are equal.

Answer to Problem 51E

Electrons are negatively charged, protons are positively charged, neutrons have no charge.

Explanation of Solution

Dalton’s atomic theory states that matter is made up of indivisible atoms. The invention of the battery led to investigations that paved the way for doubts about the indivisibility of atoms. It was later proved that subatomic particles called neutrons, electrons and protons are present within an atom. Electrons are particles which are negatively charged and exist outside the nucleus. Protons are particles which are positively charged and exist inside the nucleus. Neutrons are particles which do not have any charge. They exist within the nucleus of an atom.

Conclusion

Negatively charged subatomic particles are termed as electrons. Positively charged subatomic particles are termed as protons. Subatomic particles which have no charge are termed as neutrons.

Interpretation Introduction

(c)

Interpretation:

The terms, nuclear model of the atom, and nucleus are to be distinguished precisely.

Concept introduction:

The nuclear model of an atom is a result of Rutherford’s scattering experiment. In the nuclear model, the proton and neutrons are in the nucleus of the atom. They make up almost the entire mass of the atom.

Answer to Problem 51E

Nucleus is the positively charged core of the atom located at the center of the atom. Nuclear model of an atom describes the complete structure of the atom including the nucleus.

Explanation of Solution

The nuclear model of the atom is a result of Rutherford’s scattering experiments to determine the structure of an atom. According to the nuclear model of an atom, atoms consist of a positively charged dense nucleus surrounded by negatively charged electrons which move in an orbit around the nucleus. The nucleus is the positively charged core of the atom. Therefore, nuclear model of the atom describes the entire structure of the atom while the term nucleus is used to define the positively charged core of the atom around which electrons rotate in an orbit.

Conclusion

The positively charged core of the electron located at the center of the atom is termed as nucleus of the atom. The complete structure of the atom, along with the nucleus is explained by the nuclear model of an atom.

Interpretation Introduction

(d)

Interpretation:

The terms, atomic number, and mass number are to be distinguished precisely.

Concept introduction:

An atom is made up of three subatomic particles-neutrons, protons, and electrons. Neutron and protons are present in the nucleus of the atom, whereas electrons are revolving outside the nucleus in an atom. In a neutral atom number of electrons and the number of protons are equal.

Answer to Problem 51E

The atomic number of the element is equal to the number of protons present in an atom of the element. The mass number of an element is equal to the sum of the neutrons and protons present in the atom of the element.

Explanation of Solution

Dalton’s atomic theory states that matter is made up of indivisible atoms. The invention of the battery led to investigations which paved the way for doubts about the indivisibility of atoms. It was later proved that subatomic particles called neutrons, electrons and protons are present within an atom. The number of protons of an element is equal to its atomic number. The sum of the number of protons and neutrons is equal to the mass number of the element.

Conclusion

The total number of protons and neutrons of an element is equal to its mass number. The number of protons is equal to the atomic number of the element.

Interpretation Introduction

(e)

Interpretation:

The terms, chemical symbol of an element, and nuclear symbol are to be distinguished precisely.

Concept introduction:

Elements are made up of the same type of atoms. An atom is made up of three subatomic particles-neutrons, protons, and electrons. Neutron and protons are present in the nucleus of the atom, whereas electrons are revolving outside the nucleus in an atom. In a neutral atom number of electrons and the number of protons are equal.

Answer to Problem 51E

The short notation for the scientific or Latin name of an element is termed as the chemical symbol of an element. When the chemical symbol is accompanied by the mass number and atomic number as superscript and subscript, it is known as the nuclear symbol of the element.

Explanation of Solution

The chemical symbol of an element is a short notation for the scientific name of the element. The chemical symbol is sometimes derived from the Latin name of an element.

The nuclear symbol consists of the chemical symbol with the mass number of the element as a superscript and the atomic number of the element as the subscript. For example, the chemical symbol of helium is $\text{He}$, while the nuclear symbol is ${}_2^4\text{He}$.

Conclusion

The chemical symbol is a short notation for the scientific or Latin name of the element. The nuclear symbol consists of the mass number and atomic number along with the chemical symbol.

Interpretation Introduction

(f)

Interpretation:

The terms, atom and isotope are to be distinguished precisely.

Concept introduction:

An atom is made up of three subatomic particles-neutrons, protons, and electrons. Neutron and protons are present in the nucleus of the atom, whereas electrons are revolving outside the nucleus in an atom. In a neutral atom number of electrons and the number of protons are equal.

Answer to Problem 51E

Atoms make up matter and consist of neutrons, protons and electrons. A single isotope of an element is made up of identical atoms.

Explanation of Solution

Atoms are the constituent particles of matter. They are made up of subatomic particles, namely- electrons, neutrons and protons. Isotopes of an element have the same atomic number but different mass number. An isotope is made up of identical atoms.

Conclusion

Atoms make up matter and consist of neutrons, protons and electrons. A single isotope of an element is made up of identical atoms.

Interpretation Introduction

(g)

Interpretation:

The terms, atomic mass and atomic mass unit are to be distinguished precisely.

Concept introduction:

Elements are made up of atoms. Atoms are the constituent particles of matter. They are made up of subatomic particles, namely- electron, neutrons and protons. Isotopes of an element have the same atomic number but different mass numbers. An isotope is made up of identical atoms.

Answer to Problem 51E

Atomic mass is the average of masses of all the natural isotopes of the element. Atomic mass unit is a unit of mass.

Explanation of Solution

The atomic mass of an element is the average mass of all the natural isotopes of the element. One atom of carbon $-12$ has the mass of $12$ atomic mass units. $1$ atomic mass unit is $1/12$ of the mass of a carbon atom. Therefore, atomic mass unit is a unit of mass.

Conclusion

The average of masses of all the natural isotopes of the element is termed as atomic mass. Atomic mass unit is a unit of mass.

Interpretation Introduction

(h)

Interpretation:

The terms, atomic mass of an element and atomic mass of an isotope are to be distinguished precisely.

Concept introduction:

Elements are made up of atoms. Atoms are the constituent particles of matter. They are made up of subatomic particles, namely- electrons, neutrons and protons. Isotopes of an element have the same atomic number but different mass numbers. An isotope is made up of identical atoms.

Answer to Problem 51E

Atomic mass of an element is defined as the average of masses of all the natural isotopes of the element. Atomic mass of an isotope refers to the mass of the atom of that isotope.

Explanation of Solution

The atomic mass of an element is the average mass of all the natural isotopes of the element. The atomic mass of an isotope is the mass of an atom of that particular isotope. The term atomic mass is the same as average atomic mass.

Conclusion

Atomic mass is the average of masses of all the natural isotopes of the element. Atomic mass of an isotope is the mass of the atom of that isotope.

Interpretation Introduction

(i)

Interpretation:

The terms, period and group, or family are to be distinguished precisely.

Concept introduction:

The elements in a modern periodic table are arranged in an increasing order of their atomic number. There are $7$ periods and $18$ groups in a modern periodic table. They are categorized into groups based on the type of energy sublevel that the last valence electron of the element enters.

Answer to Problem 51E

Periodic table consists of horizontal rows known as periods. The vertical columns in the periodic table are known as groups. Groups are also termed as family.

Explanation of Solution

In the modern periodic table, the horizontal rows are known as periods. The periods are numbered from top to bottom. The first period contains $2$ elements, the second and third contain $8$ elements and the fourth and fifth contain $18$ elements. The sixth and seventh period contain $32$ elements. The vertical columns in a periodic table are known as groups. Elements with similar properties are placed within one group. Groups are also termed as family.

Conclusion

The horizontal rows in the periodic table are termed as periods. The vertical columns in the periodic table are termed as groups. The groups are also termed as family.

Interpretation Introduction

(j)

Interpretation:

The terms, main group element and transition element are to be distinguished precisely.

Concept introduction:

The elements in a modern periodic table are arranged in an increasing order of their atomic number. There are $7$ periods and $18$ groups in a modern periodic table. They are categorized into groups based on the type of energy sublevel that the last valence electron of the element enters.

Answer to Problem 51E

The main group elements belong to the groups $1,2$ and $13$ to $18$. The transition elements belong to the groups $3$ to $12$.

Explanation of Solution

In the modern periodic table, the horizontal rows are known as periods and the vertical columns in a periodic table are known as groups. Elements with similar properties are placed within one group. The elements from the groups $1,2$ and $13$ to $18$ are called main group elements. Elements in group $3$ to $12$ are called transition elements.

Conclusion

The groups, $1,2$ and $13$ to $18$ contain the main group elements. The groups $3$ to $12$ contain the transition elements.