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QUIZ

A+ for Chemistry!! Elements, Compounds & MixturesElementsAn element is a pure substance made of only 1 type of atoms.

CompoundsA compound is a pure substance made of 2 or more elements that are chemically combined.

Examples of Compounds

Sodium (Na)+Chlorine (Cl)NaClHydrogen (H) + Oxygen (O)H2OCarbon (C) + Oxygen (O)CO2

Compounds contain elementsProperties of compounds are different from elementsCompounds CAN be separated by chemical meansMixturesA mixture is a combination of 2 or more substances that are not chemically combined.

Examples of Mixtures

chicken noodle souppizza yes, that would be Yoda

salad

Properties of Mixtures:Each substance in a mixture has its own propertyMixtures can be separated by physical means

Write whether each of the following is an ELEMENT, COMPOUND or MIXTURE

CARBON DIOXIDEAMMONIAWATER (VAPOUR)AIROXYGENARGONNITROGENHYDROGENWrite whether each of the following is an ELEMENT, COMPOUND or MIXTURE

PropertyMetalsNon-MetalsAppearanceShinyDullMelting & boiling pointHigh. Except Hg is a liquidLow. Except Br2 is a liquidDensityHigh ( Feel Heavy)Low (Feel Light)StrengthStrongNot StrongMalleabilityMalleable (Changed into sheets)Not MalleableDuctilityDuctile (Changed into wires)Not DuctileHeat ConductivityGoodPoorElectrical ConductivityGoodPoor

Metals: Copper (Cu), tin (Sn), lead (Pb), iron (Fe), gold (Au), mercury (Hg)

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Nonmetals: sulfur (S), iodine (I), neon (Ne), chlorine (Cl), oxygen (O), hydrogen (H)ALLOYSAlloys are mixtures of .Metal + MetalMetal + Nonmetal

They are usually more stronger than metals!!!

When you hit the metal, the layers can slide..forceMetal

forceBut for alloys, when you hit, the layers cannot slide..because the atoms are of different size!!So More STRONG than metalsDifferent types of steelSteel = IRON + CARBON= IRON + CARBON + Chromium / Nickel= IRON + CARBON + ManganeseExamples of Alloys

Brass = Copper + Zinc.

Bronze = Copper + Tin Solder = Zinc + Lead Amalgam = Mercury + Silver BondingEvery Atom wants to become stable - have a complete outer most shell.To become stable; it canGain electronsLoose electrons

An attraction between two or more atoms to become stable (have a complete outermost shell) is called a Chemical Bond.

Types of BondsIonic BondCovalent BondMetallic Bond

IONIC BONDINGIonic bond An IONIC BOND is an electrostatic interaction that holds together a positively charged ion (cation) and a negatively charged ion (anion).

Ionic bond are usually formed between atoms of non-metal and metal.In an ionic bond, one atom loses an electron to another atom, forming a cation and anion, respectively.

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A neutral atom becomes an ion either by losing an electron (cation) or by gaining an electron (anion). Strong electrostatic forcesCation formation Cation : an atom that donates electron and forms positive ion. Normally happens in metal atoms.

Sodium atom(2.8.1)Charge for 11 protons = +11Charge for 11 electrons = -11Total charge = 0Sodium ion(2.8)Charge for 11 protons = +11Charge for 10 electrons = -10Total charge = +1+Na Na+ + eNaNaDonate 1 electronNo

Atom

Equation

Ion

1

Li

2

Mg

3

Zn

4

Cu

5

Al

Try this!Li Li+ + e

Mg Mg2+ + 2eZn Zn2+ + 2eCu Cu2+ + 2eAl Al3+ + 3eLi+Mg2+Zn2+Cu2+Al3+Anion formation Anion : An atom that receives electron and forms negative ion. Normally happens in non-metal atoms. Fluorine atom(2.7)Charge for 9 protons = +9Charge for 9 electrons = -9Total charge = 0Fluoride ion(2.8)Charge for 9 protons = +9Charge for 10 electrons = -10Total charge = -1F + e F- F-FAccepts 1 electronNo

Atom

Equation

Ion

1

Cl

2

Br

3

O

Try this!Cl + e Cl-Br + e Br-O + 2e O2-Cl-Br-O2- When positive ion (cation) and negative ion (anion) attract to each other an ionic bond is formed.

Sometimes ionic bond is also known as electrovalent bond and the compound is an ionic compound. Formation of IONIC Compound(SODIUM CHLORIDE)ClSODIUM ATOM2,8,1NaCHLORINE ATOM2,8,7SODIUM CHLORIDEClSODIUM ION2,8NaCHLORIDE ION2,8,8both atomic species now have full outer shells; They have a Noble Gas Configuration+CationAnion

CALCIUM CHLORIDEClCALCIUM ATOM2,8,8,2CaCHLORINE ATOMS2,8,7ClCALCIUM CHLORIDEClCALCIUM ION2,8,8CaCHLORIDE IONS2,8,8Cl2+MAGNESIUM OXIDEOMAGNESIUM ATOM2,8,2MgOXYGEN ATOM2,6MAGNESIUM OXIDEMAGNESIUM ION2,8Mg2+OXIDE ION2,8O2-IONIC BONDING IN SODIUM CHLORIDE

Cl- chloride ion

Na+ sodium ion

1 Sodium Ion is SURROUNDED by 6 Chloride Ions 1 Chloride Ion is SURROUNDED by 6 Sodium Ions Cl- Chloride ion Na+ Sodium ionIF YOU SEE INSIDE .

IONIC BONDING IN SODIUM CHLORIDE

Cl- chloride ion

Na+ sodium ionAll the ions attract each other by STRONG ELECTROSTATIC FORCES in all directions

IONIC BONDING IN SODIUM CHLORIDE

Cl- chloride ion

Na+ sodium ionSo there is no SINGLE Molecule of NaCl, just a big structure with same number of Na and Cl Ions Called IONIC LATTICEYOU DO NOT GET MOLECULES OF SODIUM CHLORIDECOVALENT BONDINGHow can atoms become stable if they do not want to loose or gain electrons?Covalent bond are found between the atoms in molecules.

Molecules can be SIMPLE MOLECULESH2, CO2, CH4

or GIANT MOLECULES diamond, graphite, silica

Covalent bond Covalent bond is a bond that formed by the sharing of electrons.It can be formed between atoms of non-metals. The bonds can be formed between atoms of the same element or between atoms of different elements. H H Both Hydrogen atoms needs 1 electron to complete its outer shell (become stable)So they will SHARE 1 PAIR of electrons to become stable!Hence both atoms have noble gas configurationH HHHThis attraction between two atoms is called COVALENT BONDBut any one of them will not give electron to the other!!! Simple MoleculesCHLORINEBoth Chlorine atom needs one electron to complete its outer shell Atoms share a pair of electronsClClCl Cl Cl ClSimple MoleculesHYDROGEN CHLORIDEClHBoth atoms need one electron to complete its outer shell Atoms share 1 pair of electronsH Cl H ClSimple MoleculesMETHANECEach hydrogen atom needs 1 electron to complete its outer shell A carbon atom needs 4 electrons to complete its outer shell Carbon shares all 4 of its electrons to form 4 single covalent bondsHHHHH C H HHH C HHHSimple MoleculesAMMONIANEach hydrogen atom needs one electron to complete its outer shell Nitrogen atom needs 3 electrons to complete its outer shell Nitrogen can only share 3 of its 5 electrons otherwise it will exceed the maximum of 8So 2 electrons REMAINS!HHHH N HHH N HHLone pairSimple MoleculesWATEREach hydrogen atom needs one electron to complete its outer shell Oxygen atom needs 2 electrons to complete its outer shell Oxygen can only share 2 of its 6 electrons otherwise it will exceed the maximum of 82 LONE PAIRS REMAINHHH O HH OHOSimple MoleculesOXYGENOeach oxygen atom needs two electrons to complete its outer shell each oxygen shares 2 of its electrons (4 electrons = 2 Pairs) to form a DOUBLE COVALENT BONDOOOO O

O2

Simple MoleculesNow try to draw .N2C2H4CH3OH & CO2

Simple MoleculesA single covalent bond consist of two electonsA double covalent bond consist of four electonsA triple covalent bond consist of six electons

N NO OH - ClPropertyIonic CompoundsCovalent CompoundsSolubilitySoluble in WaterNot Soluble in WaterConductivityIn Solid state: Do not ConductIn Molten or when dissolved in water: ConductDo no conduct ElectricityM.P and B.P Usually very highUsually low They are BrittleSimple MoleculesGiantMolecules

GiantMoleculesEach C atom is joined to 4 other C atoms in a giant lattice

Diamond

GiantMoleculesMany bonds must be broken to separate all C atoms. Hence MELTING POINT is very high and it is VERY STRONGDiamond

GiantMoleculesDiamondAll 4 electrons of C are used in bonding. So No free electrons . So, DO NOT CONDUCT ELECTRICITY!

Uses of DiamondUsed in JewelryUsed in cutting glass and rocks (Drilling

GiantMolecules

Each carbon atom is joined to 3 other Carbon atoms in one layer of the giant lattice

So many bonds must be broken to separate. Hence MELTING POINT is very high

Graphite

GiantMolecules

The force of attraction between two layers is very weak. So it is SOFT Graphite

GiantMolecules

Only 3 electrons of Carbon are used for bonding. So the 4rth electron of every carbon is free to move. Hence it CONDUCTS ELECTRICITY! Graphite

GiantMolecules

GraphiteThe layers can slide over each other So being soft - used as a Lubricant Pencils

GiantMoleculesEach Si atom is joined to 4 O atoms &

Each O atom is joined to two Si atoms

silicon atomsoxygen atomsSilica/ Silicon (IV) Oxide/ Silicon Dioxide/ QuartzGiantMoleculesAll bonds between Si & O atoms are Covalent Bonds. So many bonds must be broken to separate.

Hence MELTING POINT is very high and it is STRONG

silicon atomsoxygen atomsSilica/ Silicon (IV) Oxide/ Silicon Dioxide/ QuartzGiantMoleculesAll electrons of Si and O are used in bonding. So no free electrons. Hence, DO NOT CONDUCT ELECTRICITY.

silicon atomsoxygen atomsSilica/ Silicon (IV) Oxide/ Silicon Dioxide/ QuartzGiantMoleculesPropertyDiamondGraphiteSilicon DioxideM.p and B.pHardnessConducting electricityConducting heatThe Solid StateGiantMoleculesPropertyDiamondGraphiteSilicon DioxideM.p and B.pVery highVery highVery highHardnessHardSoft (so used as lubricant) HardConducting electricityNoYesNoConducting heatNoyesnoThe Solid StateGiantMoleculesMETALLIC BONDINGAll metal atoms are arranged in a regular pattern - Lattice

Metal atoms have tendency to loose electrons to become stable

So, the metal atoms loose electrons & become Cations. The released electrons are free to move in the metal CationsFree / Delocalized Electrons / Sea of electronsThe force of attraction between the free electrons and the metal cations is called Metallic Bonding.

NaNaNaNaNaNaNaNaNaNaNaNaNaNaNa