Ch.7 - Periodic Properties of the Elements

Problem 108a

Previous problem

Next problem

Chapter 7, Problem 108a

We will see in Chapter 12 that semiconductors are materials that conduct electricity better than nonmetals but not as well as metals. The only two elements in the periodic table that are technologically useful semiconductors are silicon and germanium. Integrated circuits in computer chips today are based on silicon. Compound semiconductors are also used in the electronics industry. Examples are gallium arsenide, GaAs; gallium phosphide, GaP; cadmium sulfide, CdS; and cadmium selenide, CdSe. (a) What is the relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table relative to Si and Ge?

Verified step by step guidance

Identify the position of silicon (Si) and germanium (Ge) on the periodic table. Both are in group 14, which is also known as the carbon group.

Observe that compound semiconductors like GaAs, GaP, CdS, and CdSe are made from elements in groups 13 and 15, or groups 12 and 16.

Note that the elements in these compound semiconductors are positioned symmetrically around group 14 on the periodic table. For example, gallium (Ga) is in group 13 and arsenic (As) is in group 15.

Understand that this positioning allows these compounds to mimic the electronic structure of group 14 elements, like Si and Ge, which is crucial for their semiconductor properties.

Conclude that the relationship between the compound semiconductors' compositions and the positions of their elements on the periodic table is based on their ability to form a similar electronic configuration to that of Si and Ge, enabling them to function as semiconductors.

Verified Solution

Video duration:

This video solution was recommended by our tutors as helpful for the problem above.

Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Semiconductors

Semiconductors are materials that have electrical conductivity between that of conductors (like metals) and insulators (like nonmetals). Their ability to conduct electricity can be altered by adding impurities, a process known as doping. This property makes them essential in electronic devices, as they can be engineered to control electrical current effectively.

Periodic Table Positioning

The position of an element in the periodic table provides insight into its chemical properties, including its conductivity. Elements in the same group often exhibit similar behaviors due to their valence electron configurations. For semiconductors, elements like silicon (Si) and germanium (Ge) are found in group 14, while compound semiconductors often consist of elements from groups 13 and 15, influencing their electronic properties.

Compound Semiconductors

Compound semiconductors are formed from two or more elements, typically from different groups of the periodic table, which allows for unique electronic properties. For example, gallium arsenide (GaAs) combines gallium from group 13 and arsenic from group 15, resulting in a material with superior electron mobility compared to silicon. These compounds are crucial in high-frequency and optoelectronic applications.

Recommended video:

Guided course

02:11

Ionic Compounds Naming

Previous problem

Next problem

Related Practice

Open Question

Zinc in its 2+ oxidation state is an essential metal ion for life. Zn2+ is found bound to many proteins that are involved in biological processes, but unfortunately, Zn2+ is hard to detect by common chemical methods. Therefore, scientists interested in studying Zn2+-containing proteins frequently substitute Cd2+ for Zn2+, since Cd2+ is easier to detect. On the basis of the properties of the elements and ions discussed in this chapter and their positions on the periodic table, describe the pros and cons of using Cd2+ as a Zn2+ substitute. Proteins that speed up (catalyze) chemical reactions are called enzymes. Many enzymes are required for proper metabolic reactions in the body. One problem with using Cd2+ to replace Zn2+ in enzymes is that Cd2+ substitution can decrease or even eliminate enzymatic activity. Can you suggest a different metal ion that might replace Zn2+ in enzymes instead of Cd2+? Justify your answer.

Textbook Question

A historian discovers a nineteenth-century notebook in which some observations, dated 1822, were recorded on a substance thought to be a new element. Here are some of the data recorded in the notebook: 'Ductile, silver-white, metallic looking. Softer than lead. Unaffected by water. Stable in air. Melting point: 153 °C. Density: 7.3 g>cm3. Electrical conductivity: 20% that of copper. Hardness: About 1% as hard as iron. When 4.20 g of the unknown is heated in an excess of oxygen, 5.08 g of a white solid is formed. The solid could be sublimed by heating to over 800 °C.' (a) Using information in the text and the CRC Handbook of Chemistry and Physics, and making allowances for possible variations in numbers from current values, identify the element reported.

466

views

Open Question

In April 2010, a research team reported that it had made Element 117. This discovery was confirmed in 2012 by additional experiments. Write the ground-state electron configuration for Element 117 and estimate values for its first ionization energy, electron affinity, atomic size, and common oxidation state based on its position in the periodic table.

Textbook Question

We will see in Chapter 12 that semiconductors are materials that conduct electricity better than nonmetals but not as well as metals. The only two elements in the periodic table that are technologically useful semiconductors are silicon and germanium. Integrated circuits in computer chips today are based on silicon. Compound semiconductors are also used in the electronics industry. Examples are gallium arsenide, GaAs; gallium phosphide, GaP; cadmium sulfide, CdS; and cadmium selenide, CdSe. (b) Workers in the semiconductor industry refer to 'II–VI' and 'III–V' materials, using Roman numerals. Can you identify which compound semiconductors are II–VI and which are III–V?

297

views

Textbook Question

Moseley established the concept of atomic number by studying X rays emitted by the elements. The X rays emitted by some of the elements have the following wavelengths: Element Wavelength (pm) Ne 1461 Ca 335.8 Zn 143.5 Zr 78.6 Sn 49.1 (e) A particular element emits X rays with a wavelength of 98.0 pm. What element do you think it is?

427

views

Textbook Question

Moseley established the concept of atomic number by studying X rays emitted by the elements. The X rays emitted by some of the elements have the following wavelengths: Element Wavelength (pm) Ne 1461 Ca 335.8 Zn 143.5 Zr 78.6 Sn 49.1 (a) Calculate the frequency, n, of the X rays emitted by each of the elements, in Hz.

788

views