the language of chemistry chemical elements -chemical elements - –pure substances that cannot be...
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The Language of The Language of ChemistryChemistryThe Language of The Language of ChemistryChemistry
• CHEMICAL ELEMENTSCHEMICAL ELEMENTS - - – pure substances that cannot be decomposed by pure substances that cannot be decomposed by
ordinary means to other substances.ordinary means to other substances.
SodiumBromine
Aluminum
The Language of The Language of ChemistryChemistryThe Language of The Language of ChemistryChemistry
• The elements, The elements, their names, and their names, and symbols are given symbols are given on theon the PERIODIC PERIODIC TABLETABLE
• How many How many elements are elements are there?there?
Copper Copper atoms on atoms on silica silica surface.surface.
See CD-See CD-ROM ROM Screen 1.4Screen 1.4
• An An atomatom is the smallest particle of an is the smallest particle of an element that has the chemical element that has the chemical properties of the element.properties of the element.
Distance across = 1.8 nanometer (1.8 x 10-9 m)
An atom consists of aAn atom consists of a
• nucleusnucleus
–(of (of protonsprotons and and neutronsneutrons) )
• electronselectrons in space about the nucleus. in space about the nucleus.
The The AtomAtom
Electron cloudElectron cloud
NucleusNucleus
The red compound is composed of• nickel (Ni) (silver)• carbon (C) (black)• hydrogen (H) (white)
• oxygen (O) (red)• nitrogen (N) (blue)
The red compound is composed of• nickel (Ni) (silver)• carbon (C) (black)• hydrogen (H) (white)
• oxygen (O) (red)• nitrogen (N) (blue)
CHEMICAL COMPOUNDSCHEMICAL COMPOUNDS are composed of atoms and so can are composed of atoms and so can be decomposed to those atoms.be decomposed to those atoms.
AA MOLECULEMOLECULE is the smallest unit is the smallest unit of a compound that retains the chemical of a compound that retains the chemical characteristics of the compound.characteristics of the compound.Composition of molecules is given by aComposition of molecules is given by a MOLECULAR FORMULAMOLECULAR FORMULA
HH22OO CC88HH1010NN44OO22 - caffeine - caffeine
Chemical Properties and Chemical Properties and Chemical ChangeChemical Change
• Chemical change Chemical change or or chemical reactionchemical reaction — — transformation of one or transformation of one or more atoms or molecules more atoms or molecules into one or more different into one or more different molecules.molecules.
•Burning hydrogen (HBurning hydrogen (H22) in ) in oxygen (Ooxygen (O22) gives H) gives H22O.O.
Evolution heat or light
Color change
Formation of gas
Precipitate
Chemical Change
A A Chemist’s Chemist’s
ViewView
2 H2(g) + O2 (g) --> 2 H2O(g)
MacroscopicMacroscopicMacroscopicMacroscopic
SymbolicSymbolicSymbolicSymbolicMicroscopicMicroscopicMicroscopicMicroscopic
Physical ChangesPhysical ChangesSome Some physical changes physical changes
would bewould be
• boiling of a liquidboiling of a liquid
• melting of a solidmelting of a solid
• dissolving a solid in a dissolving a solid in a liquid to give a liquid to give a homogeneous mixture homogeneous mixture — a SOLUTION.— a SOLUTION.
PhasePhase ChangesChanges
areare Changes inChanges in PositionPosition
andand areare
PhysicalPhysical ChangeChange
2. Chemical Properties
The way a substance reacts with others to form new substances with different properties.
Chemical Properties
FlamabilityReactivitycorrosion
Physical Physical PropertiesProperties
What are some physical What are some physical properties?properties?
• colorcolor
• melting and boiling melting and boiling pointpoint
• odorodor
DENSITYDENSITYDENSITYDENSITY• Density is an Density is an
INTENSIVEINTENSIVE property property of matter.of matter.
–does does NOTNOT depend on depend on quantity of matter.quantity of matter.
– temperaturetemperature
• Contrast with Contrast with EXTENSIVEEXTENSIVE
–depends on quantity depends on quantity of matter.of matter.
–mass and volume.mass and volume.
StyrofoamStyrofoam BrickBrick
DENSITYDENSITY - an important - an important and useful physical propertyand useful physical property
Density mass (g)volume (cm3)
Density mass (g)volume (cm3)
Mercury
13.6 g/cm13.6 g/cm33 21.5 g/cm21.5 g/cm33
Aluminum
2.7 g/cm2.7 g/cm33
Platinum
ProblemProblem A piece of copper has a A piece of copper has a mass of 57.54 g. It is 9.36 cm long, mass of 57.54 g. It is 9.36 cm long, 7.23 cm wide, and 0.95 mm thick. 7.23 cm wide, and 0.95 mm thick. Calculate density (g/cmCalculate density (g/cm33).).
Density mass (g)volume (cm3)
Density mass (g)volume (cm3)
STATES OF MATTERSTATES OF MATTERSTATES OF MATTERSTATES OF MATTER•SOLIDSSOLIDS — have rigid shape, fixed — have rigid shape, fixed
volume. External shape can reflect the volume. External shape can reflect the atomic and molecular arrangement.atomic and molecular arrangement.
–Reasonably well understood.Reasonably well understood.
•LIQUIDSLIQUIDS — have no fixed shape and — have no fixed shape and may not fill a container completely. may not fill a container completely.
–Not well understood.Not well understood.
•GASESGASES — expand to fill their container. — expand to fill their container.
–Good theoretical understanding.Good theoretical understanding.
Temperature ScalesTemperature Scales
Notice that 1 kelvin degree = 1 degree Celsius1 kelvin degree = 1 degree Celsius
Boiling point Boiling point of waterof water
Freezing point Freezing point of waterof water
CelsiusCelsius
100 ˚C100 ˚C
0 ˚C0 ˚C
100˚C100˚C
KelvinKelvin
373 K373 K
273 K273 K
100 K100 K
FahrenheitFahrenheit
32 ˚F32 ˚F
212 ˚F212 ˚F
180˚F180˚F
Calculations Calculations Using Using TemperatureTemperature
• Generally require temp’s in Generally require temp’s in kelvinskelvins
• T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15
• Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K
• Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K
• Generally require temp’s in Generally require temp’s in kelvinskelvins
• T (K) = t (˚C) + 273.15T (K) = t (˚C) + 273.15
• Body temp = 37 ˚C + 273 = 310 KBody temp = 37 ˚C + 273 = 310 K
• Liquid nitrogen = -196 ˚C + 273 = 77 KLiquid nitrogen = -196 ˚C + 273 = 77 K
Kinetic Nature of MatterKinetic Nature of MatterKinetic Nature of MatterKinetic Nature of MatterMatter consists of atoms and molecules Matter consists of atoms and molecules
in motion.in motion.
Pure Substances / Mixtures
Heterogeneous Mixtures
Platinum
Homogeneous