The Nature of Materials (p.35). States of matter: Solid Liquid Gas Plasma (p. 36) (At what...

The Nature of Materials (p.35)

States of matter:

Solid Liquid Gas Plasma (p. 36)

(At what temperature and pressure?)(Sublimation)

Atomic Theory:

Planetary Model Inaccuracies in the planetary model

FIGURE 2-7 (a) Electron principal energy levels or orbits.

James A. Jacobs & Thomas F. KilduffEngineering Materials Technology, Fourth Edition

Copyright ©2001 by Prentice-Hall, Inc.Upper Saddle River, New Jersey 07458

All rights reserved.

FIGURE 2-7 (b) Block diagram of the first four energy levels showing their respective sublevels or orbitals along with the maximum number of electrons per energy level. Orbitals are used to describe the locations of electrons within the energy levels. They refer to volumes of space around the nucleus of an atom where an electron could probably be found. An orbital can be occupied by one electron or by two paired electrons only. An s orbital is spherical in shape; p orbitals have identical dumbell shapes oriented around the x-, y-,and z-axes; and d orbitals take the shape of a four-leaf clover.




Atomic structure

NucleusProtonNeutronOther

Orbits (p.41)Electron

Valence electrons (p.39)

FIGURE 2-7 (c) Electron configuration for the element carbon (C), atomic number A.N. 6 in Period 2 of the periodic table, shows three different ways of representing the location of its six electrons.







Element

Definition Atomic number Atomic weight Symbol Isotopes

Periodic Table of Elements (cover, p.44) Periods and Groups Metals Metalloids (B Si Ge As Sb Te At)

(p.45) Non-Metals

Other atomic properties

Elements, Compounds or Mixtures?

Molecular Structure and Bonding (pp. 46) Monatomic/Diatomic

Bonding

Primarycovalentionicmetallic

Secondaryvan der Waals

Covalent Bonding

electron sharing single, double, triple diagrams (p.47) strongest e.g., methane & other hydrocarbons saturated: all single bonds

FIGURE 2-11 Covalent bonding of methane.




FIGURE 2-10 Hydrocarbons.




FIGURE 2-12 Covalent bonding of ethylene.




FIGURE 2-13 Benzene or benzene ring.







FIGURE 2-14 Polymorphism of carbon. (a) Diamond’s cubic structure: each carbon atom forms strong covalent bonds with four other carbon atoms to develop a tetrahedron in the same manner as silicon and germanium; diamond cutters use a sharp instrument and a sharp blow to split crystal along cleavage planes. (111) to produce perfect smaller jewels. (b) Layered structure in graphite: van der Waal bonding between layers allows easy cleavage into sheets, thus providing good lubrication properties. (c) C-60 or fullerene molecules have a spherical shape, like a soccer ball, composed of 60 carbon atoms covalently bonded together.

Ionic Bonding (p.50)

electron swapping usu. Inorganic compounds e.g., NaCl

FIGURE 2-15 Ionic bonding (electron swapping) of a sodium chloride molecule. Upon bonding both atoms have the equivalent of eight valence electrons in their outer shells. The orbitals within the shells are not shown in this figure. The subshells are not shown.




FIGURE 2-8 Percent ionic character of a single bond plotted as a function of the difference in electronegativities of the two bonded atoms.




Metallic Bonding (p.51)

electron swarming cloud of delocalized or free electrons

FIGURE 2-16 Metallic bonding or electron swarming.




Secondary Bonding

van der Waals very weak At low temps, noble gasses form

diatoms due to van der Waals forces.




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The Nature of Materials (p.35). States of matter: Solid Liquid Gas Plasma (p. 36) (At what...

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