ATOMIC ATOMIC STRUCTURESTRUCTURE

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Structure of MatterStructure of Matter EmpedoclesEmpedocles ( (492 b.c. and 432 b.c.492 b.c. and 432 b.c.):): All matter is All matter is

composed of four main elementscomposed of four main elements

DemocritusDemocritus ( (460 b.c. to 370 b.c.460 b.c. to 370 b.c.) : I) : Infinitesimally nfinitesimally small pieces of matter small pieces of matter called called atomosatomos, meaning , meaning "indivisible." "indivisible."

Aristotle and Plato Aristotle and Plato rejected Democritus and rejected Democritus and supported Empedoclessupported Empedocles

Dalton first proposed part of his atomic theory in Dalton first proposed part of his atomic theory in 1803 1803

Atomic StructureAtomic StructureAtomsAtoms are the smallest structural units of all are the smallest structural units of all

solids, liquids & gases.solids, liquids & gases.

Atom: Atom: The smallest unit of an element that The smallest unit of an element that retains the chemical properties of the element. retains the chemical properties of the element. Atoms can exist alone or in combinations with Atoms can exist alone or in combinations with other atoms forming molecules.other atoms forming molecules.

Element: Element: One of less than 118 pure chemical One of less than 118 pure chemical substances. An element is a substance substances. An element is a substance composed of atoms with identical atomic composed of atoms with identical atomic number. number.

Molecule: Molecule: A particle formed by the A particle formed by the chemical bonding of two or more atoms. chemical bonding of two or more atoms. The molecule is the smallest particle of The molecule is the smallest particle of a chemical compound that retains the a chemical compound that retains the chemical properties of the compound.chemical properties of the compound.

Compound: Compound: A material formed by the A material formed by the chemical combination of elements in chemical combination of elements in defined proportions. Compounds can be defined proportions. Compounds can be chemically decomposed into simpler chemically decomposed into simpler substances.substances.

Proton: Proton: A sub-atomic particle with a positive A sub-atomic particle with a positive charge of 1.60x10-19 coulombs and a mass of charge of 1.60x10-19 coulombs and a mass of 1.672x10-27 kg. Protons are found in the 1.672x10-27 kg. Protons are found in the nucleus of atoms.nucleus of atoms.

Neutron: Neutron: A sub-atomic particle with no charge A sub-atomic particle with no charge and a mass of 1.675x10-27 kg. Neutrons are and a mass of 1.675x10-27 kg. Neutrons are found in the nucleus of atoms.found in the nucleus of atoms.

Electron: Electron:     A sub-atomic particle with a negative A sub-atomic particle with a negative charge of 1.60 × 10-19 charge of 1.60 × 10-19 coulombscoulombs and a mass and a mass of 9.11 × 10-31 kg. Electrons are generally of 9.11 × 10-31 kg. Electrons are generally found in orbit around the found in orbit around the nucleusnucleus of an atom, of an atom, but may be gained or lost during but may be gained or lost during ionion formation. formation.

INTERATOMIC BONDINGINTERATOMIC BONDING Atoms link to form materials. When this Atoms link to form materials. When this

linkage is self-sufficient, the resultant will be linkage is self-sufficient, the resultant will be a gas, a liquid or a solid.a gas, a liquid or a solid.

For example; For example; Atoms bond to form long chainsAtoms bond to form long chains→Polymers→PolymersAtoms bond in regular 3-D arrays→MetalsAtoms bond in regular 3-D arrays→Metals

The bonding b/w atoms is the result of the universal The bonding b/w atoms is the result of the universal tendency of all systems to take up their lowest tendency of all systems to take up their lowest energy state. Atoms achieve their lowest energy energy state. Atoms achieve their lowest energy level by the possession of 8 electrons in their outer level by the possession of 8 electrons in their outer most shell (except for the first shell which is stable most shell (except for the first shell which is stable only with 2eonly with 2e--))

Considering the periodic table, the elements Considering the periodic table, the elements having 8ehaving 8e-- in their outermost shell are inert gases. in their outermost shell are inert gases.

They are chemically inactive.They are chemically inactive.

HH HeHe

LiLi BeBe BB CC NN OO FF NeNe

NaNa MgMg AlAl SiSi PP SS ClCl ArAr

KK CaCa ScSc TiTi VV CrCr MnMn FeFe CoCo NiNi CuCu ZnZn GaGa GeGe AsAs SeSe BrBr KrKr

RbRb SrSr YY ZrZrNN

bbMoMo TcTc RuRu RhRh PdPd AgAg CdCd InIn SnSn SbSb TeTe II XeXe

CsCs BaBa ** HfHfTT

aaWW ReRe OsOs IrIr PtPt AuAu HgHg TlTl PbPb BiBi PoPo AtAt RnRn

FrFr RaRa **** RfRfHH

aaSgSg NsNs HsHs MtMt

Light Metal

s

Transient Metals Non Metals

8e-8e-

Electropositivity increases

Electronegativity increases

** LaLa CeCe PrPr NdNd PmPm SmSm EuEu GdGd TbTb DyDy HoHo ErEr TmTm YbYb LuLu

**** AcAc ThTh PaPa UU NpNp PuPu AmAm CmCm BkBk CfCf EsEs FmFm MdMd NoNo LrLr

Atoms of the elements having 5, 6, 7 eAtoms of the elements having 5, 6, 7 e-- in in their outermost shell accept 3, 2, 1 electrons their outermost shell accept 3, 2, 1 electrons respectively.respectively.

Those having 1, 2 or 3 eThose having 1, 2 or 3 e- - give up their give up their outermost shell electrons to remain with 8 eoutermost shell electrons to remain with 8 e-- in their underlaying shell.in their underlaying shell.

Atoms having 4 Atoms having 4 valance electronsvalance electrons may may behave in either way.behave in either way.

Valance electrons: Valance electrons: The electrons at the The electrons at the outermost shell.outermost shell.