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Six Types: 1) Dipole - Dipole, 2) Hydrogen-Bonding, 3) London Dispersion, 4) Metallic, - PowerPoint PPT Presentation


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Forces holding crystals together. Six Types: 1) Dipole - Dipole, 2) Hydrogen-Bonding, 3) London Dispersion, 4) Metallic, 5) ionic, 6) Covalent (network solids). Types of Crystalline Solids.

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Forces holding crystals together

  • Six Types:

    1) Dipole - Dipole,

    2) Hydrogen-Bonding,

    3) London Dispersion,

    4) Metallic,

    5) ionic,

    6) Covalent (network solids)


Types of crystalline solids
Types of Crystalline Solids

Ionic Solid: contains ions at the points of the lattice that describe the structure of the solid (NaCl).

Molecular Solid: discrete covalently bondedmolecules at each of its lattice points (sucrose, ice).


Types of crystalline solids1
Types of Crystalline Solids

Atomic Solid: Atoms at the points of the lattice that describe the structure of the solid (only one type of atom – diamond, graphite, copper).



Types of crystalline solids3
Types of Crystalline Solids

Molecular Solid: discrete covalently bondedmolecules at each of its lattice points (sucrose, ice).


Intermolecular forces

  • Intermolecular forces (IMF) have to do with

    the attraction between molecules

    versus

    the attraction between atoms within a molecule.


Molecular solids
Molecular Solids

  • WITHIN MOLECULES,

    STRONG COVALENT BONDS

    BETWEEN MOLECULES,

    RELATIVELY WEAK FORCES (Intermolecular Forces)


Intermolecular forces

  • Two Types:

    1) Dipole - Dipole Forces

    Hydrogen-Bonding

    2) London Dispersion (van der Waals) Forces,


Dipole dipole attractions

+

–

H

Cl

+

–

+

–

+

–

+

–

Dipole - Dipole attractions

  • Polar molecules have a separation of charge

  • Molecules are attracted to each other in a compound by these + and – forces.


Hydrogen bonding
Hydrogen - bonding

  • H-bonding is a special type of dipole - dipole attraction that is very strong

  • It occurs when N, O, or F are bonded to H

  • They are given a special name (H-bonding) because compounds containing these bonds are important in biological systems



London dispersion forces
London Dispersion forces

  • Non-polar molecules do not have

    permanent dipoles.

  • London dispersion (or van der Waal) forces exist in non-polar molecules

    are due to small dipoles that are temporary.


London dispersion forces1
London Dispersion forces

  • Because electrons are moving around in atoms,

    there will be instants when the charge around an atom is not symmetrical

  • The resulting tiny dipoles cause attractions between atoms/molecules


London dispersion forces2
London Dispersion forces

  • relatively weakforces that exist among noble gas atoms and nonpolar molecules. (Ar, C8H18)


London forces
London forces

Induced dipole:

Instantaneous dipole:

Eventually electrons are situated so that tiny dipoles form

A dipole forms in one atom or molecule, inducing a dipole in the other


Metallic solids
METALLIC SOLIDS

Atomic Solid: Metal Atoms at the points of the lattice.


Metallic bonding the electron sea model regular array of cations in a sea of valence electrons
Metallic BondingThe Electron Sea Model Regular Array of Cations in a “Sea” of Valence Electrons


B. Types of Bonds

Metals are good conductors because the valence electrons are able to flow freely

Valence electrons of metals can be thought of as a “sea of electrons”


B types of bonds
B. Types of Bonds

Metallic Bonding - “Electron Sea”


B types of bonds1
B. Types of Bonds

  • Metallic Bonding

  • Metals are found in:

    • Groups 1 & 2

    • middle of table in 3-12

    • Below and to left of stairstep line

  • Have luster, are dutile and malleable


B types of bonds2
B. Types of Bonds

METALLIC

e- are delocalized among metal atoms, “electron sea”

Bond Formation

atom

Smallest Unit

Types of Elements

metals


Ionic solids
IONIC SOLIDS

Contains ions at the points of the lattice (NaCl).

  • HIGH MELTING SUBSTANCES

  • HELD TOGETHER BY STRONG ELECTROSTATIC FORCES THAT EXIST BETWEEN OPPOSITELY CHARGES IONS



Ii octet rule
II. Octet Rule

  • In the formation of compounds, atoms tend to achieve the electron configuration of a noble gas.

  • Atoms either gain, lose, or share electrons to form compounds.


Iii cations
III. Cations

Loses an e-

-An atom’s loss of valence electrons produces a cation, or a positively charged ion.


Iii cations1
III. Cations

  • Metals – lose valence e- easily

  • Transition metals – have 2 valence e-, usually lose those two to form 2+ ions, but can also lose d electrons to form other ions


Iv anions
IV. Anions

  • Nonmetals easily gain e- to form negative ions to get to 8 valence e-

Gains an e-

Chloride ion


Iv anions1
IV. Anions

  • -Nonmetals usually gain e-

  • Some can gain or lose, but will gain most often


Formula unit
Formula Unit

-The lowest whole-number ratio of ions in an ionic compound.


V ionic bonds
V. Ionic Bonds

  • When oppositely charged ions attract, electrostatic force that holds them together = ionic bond

  • Compounds containing ionic bonds = ionic compounds

  • Electrons are transferred from cations to anions

  • Bonds formed between metals and nonmetals (or contain a polyatomic ion)


V ionic bonds1
V. Ionic Bonds

Na·

1s2 2s2 2p63s1 1s2 2s2 2p6 3s23p5

RESULTS IN

Na+

1s2 2s2 2p6 1s2 2s2 2p6 3s23p6


Vi properties of ionic compounds
VI. Properties of Ionic Compounds

  • Most ionic compounds are crystalline solids at room temperature.

    • Arranged in repeating three-dimensional patterns

  • Ionic compounds generally have high melting points

    • Large attractive forces result in very stable structures


Vi properties of ionic compounds1
VI. Properties of Ionic Compounds

  • Ionic compounds can conduct an electric current when melted or dissolved in water.

    • When ionic compounds are dissolved in water the crystalline structure breaks down. This allows the ions to move freely which results in conductivity.



Network atomic solids carbon silicon
NETWORK ATOMIC SOLIDS: ions move to the anode. (CARBON & SILICON)

SOLIDS CONTAINING STRONG DIRECTIONAL COVALENT BONDS TO FORM A SOLID THAT MIGHT BE BEST VIEWED AS A “GIANT MOLECULE”

EXAMPLE:

DIAMOND AND GRAPHITE



The structure of quartz si at the center of tetrahedral arrangement with 4 oxygen atoms
The Structure of Quartz ions move to the anode.Si at the center of tetrahedralarrangement with 4 oxygen atoms.


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