Chapter 16, Problem 37CI

(a)

Interpretation Introduction

Interpretation: In the following table, indicate the number of protons, neutrons, and electrons for each isotope listed:

Isotope	Number of Protons	Number of Neutrons	Number of Electrons
$\text{S}\text{i}$
$\text{S}\text{i}$
$\text{S}\text{i}$
$\text{S}\text{i}$
$\text{S}\text{i}$

Concept Introduction:Atomic number is equal to the number of protons in an element. In a neutral element the number of protons is equal to the number of electrons.Mass number is equal to the sum of the number of protons and neutrons. Number of neutrons is the difference between the mass number and the atomic number.

(b)

Interpretation Introduction

Interpretation: To writethe electron configuration and the abbreviated electron configuration of Si

Concept Introduction:The electron configuration is the distribution of electrons of an element in different orbits and orbitals.

(c)

Interpretation Introduction

Interpretation: To calculate the atomic mass for silicon using the isotopes those have a natural abundance:

  $\text{S}\text{i}$ natural abundance 92.23%, atomic mass 27.977

  $\text{S}\text{i}$ natural abundance 4.683%, atomic mass 28.976

  $\text{S}\text{i}$ natural abundance 3.087 %, atomic mass 29.974

Concept Introduction:

  $\text{Average atomic mass = }\frac{\text{(mass isotope1x \% abuandance isotope 1) + (mass isotope 2x \% abuandance isotope 2) }}{100}$

(d)

Interpretation Introduction

Interpretation: To write the balanced nuclear equations for the positron emission of Si-27and the beta decay of Si-31

Concept Introduction:A positron is a positively charged electron wherein the new element formed has the same mass number as the parent element but has -1 decreased atomic number.

Beta decay is the loss of an electron wherein the new element formed has the same mass number as the parent element but has +1 increased atomic number.

(e)

Interpretation Introduction

Interpretation: Todraw the Lewis structure and predict the shape of SiCl₄

Concept Introduction:Lewis structure shows the covalent bonds between atoms in a molecule. It also shows the lone pair of electrons on the element in the compound.

(f)

Interpretation Introduction

Interpretation: To find how many hours are needed for a sample of Si-31 with an activity of 16µCi to decay to 2.0µ Ci

Concept Introduction:Radioactive decay equation:

  $\text{N}\left(\text{t}\right){\text{ = N}}_{\text{o}}\left(\frac{\text{1}}{2}\right){}^{\frac{\text{t}}{{\text{t}}_{\text{1/2}}}}$

where No is the initial activity, N(t) is the activity at time t, and t_1/2is the half life of the radioactive substance.