Chapter 2, Problem 2.21P

Interpretation Introduction

(a)

Interpretation:

If the statement “A proton and an electron have the same mass but opposite charges” is true or false should be identified.

Concept Introduction:

A proton has positive charge and an electron has negative charge. Proton contributes in the mass of an atom, but an electron does not.

Interpretation Introduction

(b)

Interpretation:

If the statement “the mass of an electron is considerably smaller than that of a neutron” is true or false should be identified.

Concept Introduction:

Mass of neutron is slightly greater than the mass of proton which is much higher than the mass of an electron.

Interpretation Introduction

(c)

Interpretation:

If the statement “an atomic mass unit (amu) is a unit of mass” is true or false should be identified.

Concept Introduction:

Atomic mass unit is used to measure the mass of an atom.

Interpretation Introduction

(d)

Interpretation:

If the statement “One amu is equal to 1 gram” is true or false should be identified.

Concept Introduction:

Mass of an atom is very small therefore it is measured in atomic mass unit (amu).

Interpretation Introduction

(e)

Interpretation:

If the statement “the protons and neutrons of an atom are found in the nucleus” is true or false should be identified.

Concept Introduction:

In an atom protons and neutrons are found in the nucleus.

Interpretation Introduction

(f)

Interpretation:

If the statement “the electrons of an atom are found in the space surrounding the nucleus” is true or false should be identified.

Concept Introduction:

Electrons revolve around the nucleus.

Interpretation Introduction

(g)

Interpretation:

If the given statement “all atoms of the same element have the same number of protons is true or false should be identified.

Concept Introduction:

The numbers of protons in all atoms of the same element are same.

Interpretation Introduction

(h)

Interpretation:

If the statement “all the atoms of the same element have the same number of electrons” is true or false should be identified.

Concept Introduction:

The numbers of electrons in atoms of same element are same.

Interpretation Introduction

(i)

Interpretation:

If the statement “electrons and protons repel each other” is true or false should be identified.

Concept Introduction:

Electrons are negatively charged particles while protons are positively charged.

Interpretation Introduction

(j)

Interpretation:

If the statement “the size of an atom is approximately the size of its nucleus” is true or false should be identified.

Concept Introduction:

Nucleus is present at the center of an atom consisting of neutrons and protons.

(k)

Interpretation Introduction

Interpretation:

If the statement “the mass number of an atom is the sum of the numbers of protons and neutrons in the nucleus of that atom” is true or false should be identified.

Concept Introduction:

Mass number of an atom is defined as the sum of the number of protons and neutrons present in its nucleus.

Interpretation Introduction

(l)

Interpretation:

If the statement “for most atoms, their mass number is the same as their atomic number” is true or false should be identified.

Concept Introduction:

The mass number (A) of an atom is the sum of the numbers of protons and neutrons present in the nucleus of that atom.

The atomic number (Z) of an element is the number of protons present in its nucleus.

Interpretation Introduction

(m)

Interpretation:

If the statement “the three isotopes of hydrogen (hydrogen-1, hydrogen-2 and hydrogen-3) differ only in the number of neutrons in the nucleus” is true or false should be identified.

Concept Introduction:

Atoms with the same number of protons but different numbers of neutrons are called isotopes.

Interpretation Introduction

(n)

Interpretation:

If the statement“Hydrogen-1 has one neutron in its nucleus, hydrogen-2 has two neutrons in its nucleus and hydrogen-3 has three neutrons” is true or false should be identified.

Concept Introduction:

Atoms with the same number of protons but different number of neutrons are called isotopes.

Interpretation Introduction

(o)

Interpretation:

If the statement“All isotopes of an element have the same number of electrons”. Is true or false should be identified.

Concept Introduction:

Atoms with the same number of protons but different number of neutrons are called isotopes.

Interpretation Introduction

(p)

Interpretation:

If the statement “most elements found on Earth are mixtures of isotopes” is true or false should be identified.

Concept Introduction:

Most elements found on Earth are mixtures of isotopes, in a constant ratio.

Interpretation Introduction

(q)

Interpretation:

If the statement “the atomic weight of an element given in the Periodic Table is the weighted average of the masses of its isotopes found on Earth” is true or false should be identified.

Concept Introduction:

The atomic weight of an element given in the Periodic Table is the weighted average of the masses (in amu) of its isotopes found on Earth.

Interpretation Introduction

(r)

Interpretation:

If the statement “the atomic weights of most elements are whole numbers” is true or false should be identified.

Concept Introduction:

The atomic weight of an element given in the Periodic Table is the weighted average of the masses of its isotopes found on Earth.

Interpretation Introduction

(s)

Interpretation:

If the statement “most of the mass of an atom is found in its nucleus” is true or false should be identified.

Concept Introduction:

Mass of an atom is the sum of mass of protons and neutrons present in its nucleus.

Interpretation Introduction

(t)

Interpretation:

If the statement “the density of a nucleus is its mass number expressed in grams” is true or false should be identified.

Concept Introduction:

Density is defined as mass per unit volume.