Characteristics of Solids

Characteristics of SolidsReview

Element One of over 118 types of pure substances from which all material are formedAtom The smallest particle of an element which all materials are formed.The Periodic TableIs an organizational tool which can be used to predict chemical and physical characteristics of elements.Its all in the family-

For example, if you are in Family 18, the Noble Gases, you and all the other elements in that group/family Neon, Argon, Krypton, Xenon and Radon have similar characteristics.

Group18The StaircaseMetals : to the left of the staircaseabout 75% of all the elements lustrous, malleable, ductile, conduct heat and electricity Nonmetals: on the right sides of the staircasedull, brittle, insulators

Metalloids: on the staircase also know as semi-metalsoften semi- conductors some properties of both metals & nonmetals

How was the table formed?Chemists discovered that as the quantity of matter (atomic mass) increased, characteristics tended to repeat themselves in a predictable pattern. This was called Periodicity.When elements were placed in a table , those with similar properties were placed in a column, it produced vertical Families.

Period = the 7 horizontal rowPeriods represents the number of layers of electrons in the atom.

Family = a vertical column (group)These elements have similar properties and reactivity

Rows and Columns

An example of periodicity

example of periodicity

Column 18Noble gasesvery stabledont want to form compounds or bonds

Column 17halogenswant one more electronmost reactive nonmetalscan take an electron from almost anyone

Column 1alkali metalswant to give away one electronmost reactive metals

Family Names

TrendsReactivity of metals In which direction does reactivity increase?To the left or to the right?

Reactivity of Nonmetals Nonmetals react exactly the opposite of metals!!

MODEL OF A Lithium ATOM

3 types of Subatomic Particles 1. Electrons Is outside the nucleus and has a negative charge.2. Protons A positively charged particle in the nucleus of a Atom. It is the same mass as a Neutron 3. Neutron An uncharged particle located in the Nucleus of an Atom. It is the same mass as a Proton.

Composition of an AtomNucleus The central portion of an atom usually consisting of protons and neutrons and contains almost all the mass of the atom.Atomic Number A number representing the number of protons in an atom of an element. DefinitionsMass The amount of material (stuff) in an object. Mass is proportional to weight. Mass does not change when gravity changes while weight does. Definitions

Subatomic ParticlesNameProtons (p or +)Neutrons (n)Electrons (e-)Charge+1No charge-1Locationin nucleusin nucleusin shells around nucleusMass 1 amu 1 amu 2000 x smallerJobDetermines identity of elementSupplies proper mass to hold nucleus togetherDetermines bonding/ how it reactsNumberAtomic #Atomic mass atomic # = # of neutronsSame as # of protonsExampleSilver:Symbol AgAtomic Number of Silver is? 47How many Protons does Ag have? 47 How many Electrons does Ag have? 47How many Electron layers? 5

Valence Electrons Electrons found in the outermost energy level or layer from the nucleus. (These electrons are involved in bonding.)

Metal have a tendency to lose their valence electrons.

Nonmetals try to obtain valence electrons.

DefinitionsFinally we are done for today.

Finish Periodic Table/ Atom Work Sheet

Crystal Structures Crystal An object with a regularly repeating arrangement of its atoms.

Crystal Lattice The pattern that atomic particles form in a crystalline solid.1) Body-Centered Cubic (BCC) A type of crystalline structure that is composed of 8 particles forming a cube with a 9th particle in the center of the cube. 14 different Crystalline Systems, most metals fall into 3 categories

2) Face-Centered Cubic (FCC) A type of crystalline structure that is composed of 8 particles forming a cube and 6 more particles that are each centered in 1 of 6 faces of the cube.14 different Crystalline Systems, most metals fall into 3 categories

3) Hexagonal-Close Packed (HCP) A type of crystalline structure that is composed of 17 particles which are as closely packed as possible.14 different Crystalline Systems, most metals fall into 3 categories

Unit Cell The simplest and smallest arrangement of atoms that can be repeated to form a particular crystal.14 different Crystalline Systems, most metals fall into 3 categories

Formation of SolidsAllotropes Elements which occur in more than one form due to the way their atoms are packed.

Iron @ room Temp BCCIron above 910C FCC

Carbon can be a diamond or graphite depending on how its atoms are packed. Crystal Packing loosely packed

Is there another way these atoms could be arranged?Show next slide30

Crystal Packing More Densely PackedMost metals are close packed - that is, they fit as many atoms as possible into the available volumeAlternating the atoms has made more room the 4 halves could be joined and added to the bottom still leaving space.31Grains Influence PropertiesRapid cooling produces smaller grainsSlow cooling produces larger grainsAlloys of metals with more grains make the material stronger

Crystal Grains

Crystal grains "are regions of regularity. At the grain boundaries atoms have become misaligned. The more grain boundaries there are (the smaller the individual crystal grains), the harder and more brittle the metal becomes.Heating a metal tends to shake the atoms into a more regular arrangement - decreasing the number of grain boundaries, and so making the metal softer. Banging the metal around when it is cold tends to produce lots of small grains. Cold working therefore makes a metal harder. To restore its workability, you would need to reheat it.You can also break up the regular arrangement of the atoms by inserting atoms of a slightly different size into the structure. Alloys such as brass (a mixture of copper and zinc) are harder than the original metals because the irregularity in the structure helps to stop rows of atoms from slipping over each other.33Crystal Slip Planes in MetalTo reshape metals, layers of atoms are forced to slide over one another.

34Crystal StructureWhich type of crystal structure allows a metal to be more workable, one with many slip planes or one with fewer slip planes?

Ones with many Slip PlanesWhich type of crystal structure allows a metal slip planes to be more workable, one that is closely packed or one that is loosely packed?

Ones that are closely packed.Type of Crystal StructureClosely Packed? Many Slip Planes?WorkabilityFCCYesYesHighestBCC No YesMediumHCP YesNoLowestBCCFCCHCPChromiumIron (910C)LeadNickelPlatinumSilverCobaltMagnesiumTitaniumZincModel of Crystal Lab

Iron Wire Lab

Metallic & Non-Metallic Elements Metal Metals tend to lose electrons which changes them from neutral atoms to positive ions.

Nonmetal Nonmetals gain electrons which changes them from neutral atoms to negative ions.

Metallic & Non-Metallic Elements Ion An atom that has gained or lost at least one electron and has a negative or positive charge.

Ionic Bond A bond resulting from the attractive force between ions of opposite charges. (Metal & Non Metal bond to form a compound). A very strong bond.Electron Transfer from a metal to a non metal

Nonmetal atom becomes more stable by gaining electrons. 41

Sodium lets Chlorine use its valance electron Type of Bonding Metallic Bond The force that hold solid metal together.

In Metallic bonds the outer electron are freely moving between each atom. This free movement gives metals many of their characteristic properties. ductile, conduct electricity, thermal conductor, etc44

Metallic Bonding

All pure metals have metallic bonding and therefore exist as metallic structures. Metallic bonding consists of a regular arrangement of positive ion cores of the metals surrounded by a mobile delocalized sea of electrons.

Covalent Bonding

A chemical attraction between 2 nonmetallic atoms that are sharing electrons. (Non-Metals).

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Type of Bonding MoleculesWhen 2 or more nonmetals share electrons to form covalent bonds.

Van der Waal Forces The weaker bonds that hold molecules to one another.

Non-metalAtomsCovalentBondsMolecularCompoundVan der WaalForcesKeeps theMoleculesTogether BondingType of Bonding Covalent Network Solids Group of solids that contain only covalent bonds and are made of extremely large molecules.

Strong covalent bonds therefore very strong substancesHigh melting pointsExamples are Diamond or Silicon Carbide

Covalent Crystals: This is a crystal which has covalent bonding between all of the atoms in the crystal. An example of this is a diamond.

Type of bondingmetallicioniccovalentintermolecular Van der Waal forcesType of elements usedBetween metalsMetals and nonmetalsBetween nonmetalsBetween moleculesGivers &/or takers of electronsBetween giversBetween givers and takersBetween takersDescriptionValence e- roam freely between many atoms (delocalized). Sea of e- surrounding (+) kernels.Transfer e- Makes (+) and (-) ions that are attracted to each other.Share e- Forms discrete molecules.Hold covalently bonded molecules together as a solid. Type of material formedSolid metallic elements and alloysCeramics and glassPolymers and some ceramics/glassesHelps form solid polymersStrength of bond

Relatively strongVery strongVery strongWeakPropertiesProducedGood conductors, workable, corrode easily, generally high melt temps but variableBrittle, high melt temps, nonconductors as solids, dont corrodeInsulators, dont corrode Help determine a lot of properties of covalent compounds (polymers). Soft and plasticFormation of Solids Lab