Chapter 1 Review

1. Chapter 1 Review Megan Do & Matt Choi

2. 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.

3. 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.

4. 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

5. 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

6. Elements/ Compounds Elements • Are pure substances Compounds • Are combination of elements

7. Law of Constant Proportions • A compound always consists of the same combination of elements Example • Water is always 11% H and 89% O

8. 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.

9. Physical and Chemical Changes Physical Change • Substance changes physical appearance without altering its identity. Chemical Change • Substance transforms into a chemically different substance.

10. Separation of Mixtures Filtration • Removes solid from liquid Distillation • Boil off one or more components of the mixtures Chromatography • Exploit solubility of components

11. 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

12. Derived SI units Volume • equals (Unit of length)ᵌ=mᵌ Density • Equals Mass divided by volume Example: g/mL or g/L

13. 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

14. Dimensional Analysis • Method of calculation utilizing a knowledge of units

15. Uncertainty in Measurement Precision • How well measured quantities agree with each other Accuracy • How well measured quantities agree with “true value”

16. 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?