Matter and Measurement

Matter is anything that has mass and takes up space Atom: The smallest possible unit of matter that still maintains an element's identity during chemical reactions Molecule: two or more atoms bonded together with a covalent bond If all the atoms bonded together are of the same type the molecule formed is still an element If different types of atoms are bonded together, then the molecule formed is a compound.

Molecules of compounds Molecule of an element Figure: 01-01

Phases of Matter

Pure substances – Mixtures Elements - all the same type of atom. Compounds - substances made from two or more different kinds of atoms. (follows law of constant composition – H2O) Mixtures Homogeneous - same throughout with identical properties everywhere in the mixture. This type of mixture is called a solution Heterogeneous – two or three phases

Figure 1.9 pg 9 Figure: 01-09

Types of Changes A chemical change does produce a new substance (irreversible) A physical change does not produce a new substance (reversible)

Separation of Mixtures Filtration Distillation Chromatography

SI Base Units Physical Quantity Name of Unit Symbol length meter m mass kilogram kg time second s temperature kelvin K electric current ampere D amount of substance mole mol luminous intensity candela cd

Temperature Changes Celsius to Kelvin Kelvin to Celsius [°C] = [K] − 273.15 [K] = [°C] + 273.15 Fahrenheit to Celsius Celsius to Fahrenheit [°F] = [°C] × 9⁄5 + 32 [°C] = ([°F] − 32) × 5⁄9

Figure 1.18 pg 15 Figure: 01-18

Density = mass (m) = g/mL volume(v)  Formal definition of density is mass per unit volume  Density =  mass (m) =   g/mL     volume(v) Accuracy refers to how closely a measured value agrees with the correct value. Precision refers to how closely individual measurements agree with each other. Precise not accurate Accurate and precise

Significant Figures Non-zero numbers are always significant. Zeros between non-zero numbers are always significant. Zeros before the first non-zero digit are not significant. (Example: 0.0003 has one significant figure.) Zeros at the end of the number after a decimal place are significant. Zeros at the end of a number before a decimal place are ambiguous (e.g. 10,300 g).