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 compounds Mixtures Are a combination of two or more pure substances Each substance retains its own identity

Elements/ Compounds Elements Are pure substances Compounds 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 liquid Distillation Boil off one or more components of the mixtures Chromatography 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=mᵌ Density Equals Mass divided by volume Example: g/mL or g/L

Significant Figures Rules -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?