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 MatterSolids, 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 MatterPhysical 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?