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Chapter 1 Review
Megan Do & Matt Choi
The Study of Chemistry
• Chemistry is the study of properties of materials and changes that they undergo.
• Can be applied to all aspects of life.
The Atomic and Molecular Perspective of Chemistry
Matter• Is the physical material of the universe.• Has mass and occupies space.Elements• Are made up of unique atoms, the building of matter.Molecules• Are combinations of atoms held together in specific shapes.• Properties relate to composition and structure present.
Classifications of Matter
Solids, liquids and gases are the three forms of matter called the state of matter.• Gas – no fixed volume or shape, conforms to shape of container,
compressible; molecules far apart, move at high speeds, collide often
• Liquid – volume independent of container, rigid, incompressible; molecules closer than gas, move rapidly but can slide over each other.
• Solid – volume and shape independent of container, rigid, incompressible; molecules packed closely in definite arrangement
Pure Substances/Mixtures
Pure Substances• Are matter with fixed compositions and distinct
proportions• Are elements or compoundsMixtures• Are a combination of two or more pure substances• Each substance retains its own identity
Elements/ Compounds
Elements• Are pure substancesCompounds• Are combination of elements
Law of Constant Proportions
• A compound always consists of the same combination of elements
Example• Water is always 11% H and 89% O
Properties of Matter
Physical properties• Measured without changing the substance.Chemical properties• Describe how substances react/change to form different
substances.Intensive properties• Don’t depend on amount of substance present.Extensive properties• Depend on quantity of substance present.
Physical and Chemical Changes
Physical Change• Substance changes physical appearance
without altering its identity.Chemical Change• Substance transforms into a chemically
different substance.
Separation of Mixtures
Filtration• Removes solid from liquidDistillation• Boil off one or more components of the mixturesChromatography• Exploit solubility of components
Unit of Measurement
• Many Properties of matter are quantitative.Mass• Is a measure of the amount of material in an object.Temperature• Measure of hotness or coldness of an object.• Celsius - water freezes at 0°C ant boils at 100°C• Kelvin – Water freezes at 273K and Boils at 373K• Zero is the lowest possible temperature.• K= °C+273K
Derived SI units
Volume• equals (Unit of length)ᵌ=mᵌDensity• Equals Mass divided by volumeExample: g/mL or g/L
Significant FiguresRules- Nonzero numbers & zeros between nonzero numbers
= SIGNIFICANT- Zeros before first nonzero digit = INSIGNIFICANT- Zeros at end of number after decimal point =
SIGNIFICANT- Zeros at end of number before a decimal point are
ambiguous
Dimensional Analysis
• Method of calculation utilizing a knowledge of units
Uncertainty in Measurement
Precision • How well measured
quantities agree with each other
Accuracy• How well measured
quantities agree with “true value”
Review
• Find the density of 4.75 L of H₂SO₄• Are these measurements accurate or precise if
the actual value is 2.7 cm?
• How many atoms of hydrogen can be found in 45 g of ammonia?