Applied Health Science Technology Chapter 2

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Questions and Answers

What primarily holds the particles together in metals?

Covalent bonds

Metallic bonds (correct)

Ionic bonds

Van der Waals forces

Which characteristic best describes the electron arrangement in metals?

Fixed electrons around atoms

Delocalized electrons (correct)

Electrons tightly bound to nuclei

Localized electrons

In the context of metallic bonding, what are 'metal cations'?

Neutral atoms of metals

Positively charged ions of metals (correct)

Negatively charged particles

Free electrons in a metal

What is the role of delocalized electrons in metals?

To allow thermal conductivity Signup and view all the answers

How can the structure of metals be generally described?

As clouds of free electrons surrounding cations Signup and view all the answers

What causes the formation of dipoles in asymmetrical molecules?

Unbalanced distribution of electrons Signup and view all the answers

What is an example of a phenomenon caused by van der Waal bonds?

The attraction of gases by liquid alloys Signup and view all the answers

Which characteristic of molecules affects the strength of van der Waal bonds?

Electron distribution Signup and view all the answers

Van der Waal bonds are primarily observed in which type of substances?

Liquid alloys and gases Signup and view all the answers

Which statement is true regarding the nature of van der Waal bonds?

They arise from temporary dipoles in molecules Signup and view all the answers

How do these metals compare in reactivity to alkali metals?

They are less reactive than alkali metals. Signup and view all the answers

What do these metals produce when they react with oxygen?

Metal oxides Signup and view all the answers

Under what conditions do these metals react with water?

Only at high temperatures where water is steam Signup and view all the answers

What type of bond is formed in the H2 molecule?

Nonpolar covalent bond Signup and view all the answers

Which statement about the occurrence of these metals in nature is true?

They are too reactive to occur in pure state. Signup and view all the answers

In which aspect do these metals differ from alkali metals?

They are less reactive than alkali metals. Signup and view all the answers

How are the bonding electrons distributed in the H2 molecule?

Equally shared Signup and view all the answers

What can be inferred about the attraction of electrons in the H2 molecule?

Both atoms have equal attraction for electrons. Signup and view all the answers

What is a characteristic of a nonpolar covalent bond?

Electrons are equally shared by the bonded atoms. Signup and view all the answers

What is the implication of equal sharing of electrons in a molecule like H2?

The molecule is nonpolar. Signup and view all the answers

Which of the following elements is a non-metal in the chalcogen group?

Sulfur Signup and view all the answers

Which element in the chalcogen group is known to be radioactive?

Polonium Signup and view all the answers

What type of elements are selenium and tellurium classified as?

Semiconductors Signup and view all the answers

How many non-metals are present in the chalcogen group?

Two Signup and view all the answers

Which of the following does NOT belong to the chalcogen group?

Carbon Signup and view all the answers

What is the usual oxidation state of oxygen?

-2 Signup and view all the answers

Which of the following electronic configurations corresponds to sulfur?

Signup and view all the answers

What is the usual oxidation state of sulfur?

+6 Signup and view all the answers

Which of the following elements has an electronic configuration of [He]2s22p4?

Oxygen Signup and view all the answers

Which of the following statements about oxidation states is correct?

Sulfur can have multiple oxidation states. Signup and view all the answers

What is the common oxidation state for oxygen?

-2 Signup and view all the answers

Based on their electronic configurations, which element is likely to form compounds with higher oxidation states than oxygen?

Sulfur Signup and view all the answers

Study Notes

Chapter Two: Matter

This chapter is for Applied Health Science Technology students in Fall 2024.
The professor is Dr. Yasser Mostafa Abdallah.

Biomaterial Classification

Biomaterials can be classified by their nature:
- Metals: Amalgam, metallic denture base
- Polymers: Acrylic resin (also called polymeric materials or adhesive materials)
- Ceramics: Dental porcelain

Properties of Materials

Materials are categorized based on microscopic and macroscopic properties.

Microscopic Properties

Atomic structure: Includes atomic arrangement, e.g., sodium and chlorine.
Crystal structure: Shows crystal lattice examples: cubic body centered (bcc), cubic face centered (fcc), hexagonal. Examples include Fe, V, Nb, Cr; Al, Ni, Ag, Cu, Au; Ti, Zn, Mg, Cd.

Macroscopic Properties

Physical Properties: Based on physics laws. Describe mass, energy, force, heat, electricity, color, density, and thermal conductivity.
Mechanical Properties: A subgroup of physical properties. Describe material's ability to resist forces.
Chemical Properties: Describe setting reactions and corrosion.
Biological Properties: Describe material's effect on living tissues.

Chemical Bonding

A chemical bond is an attraction between atoms from sharing or complete transfer of electrons.
Primary Bonds:
- Ionic Bond: Electrons are completely transferred from one atom to another. This forms charged ions (cations and anions) that are attracted electrostatically. Example: Sodium (Na) reacts with Chlorine (Cl).
- Covalent Bond: Atoms share one or more pairs of electrons, achieving a full valence shell.
  - Different types: Polar or nonpolar
    - Polar Covalent bond: Electrons are unequally shared between atoms due to differences in electronegativity.
    - Nonpolar Covalent bond: Electrons are shared equally. Example: H₂
- Metallic Bond: Metal atoms lose their outer electrons to form metal cations. These free electrons are delocalized and move throughout the metal lattice. This delocalization of electrons accounts for conductivity and bonding in metals.
Secondary Bonds:
- Hydrogen Bond: Attractive force between a hydrogen atom bonded to a highly electronegative atom (like oxygen, nitrogen, or fluorine) and another electronegative atom in a separate molecule.
- van der Waals Force: Weak, temporary attractive forces between atoms or molecules due to fluctuating charges.

Examples for the Different Bonds in Dentistry

Covalent bonds join monomers in dental resin.
Ionic bonds are found in gypsum investment, phosphate cement, and ceramic.
Metallic bonds are not directly mentioned as used in dental materials but can be part of an alloy.

Periodic Table

The periodic table is arranged by increasing atomic number.
Groups or families (vertical columns) and Periods or series (horizontal rows) are shown.

Specific Element Groups

Group IA (Alkali Metals): Soft metals, reactive, have one valence electron, soluble in water. Important elements include Li, Na, K, Rb, Cs, and Fr.
Group IIA (Alkaline Earth Metals): Harder than alkali metals. They have two valence electrons. They are less reactive than alkali metals, but still react to oxygen and water. Important elements include Be, Mg, Ca, Sr, Ba, and Ra.
Group VIA (The Oxygen Family): Contains oxygen and sulfur as common elements. Important elements for this group include O and S. They exist in multiple states and forms.

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Description

Explore the fascinating world of matter in Chapter Two of Applied Health Science Technology. This chapter covers the classification of biomaterials, delving into metals, polymers, and ceramics, while also examining their microscopic and macroscopic properties. Join Dr. Yasser Mostafa Abdallah as you learn about atomic and crystal structures and the physical properties of materials.