Introduction to General Chemistry Part 1: Matter Ch. 1

What is Chemistry? Chemistry is the study of properties of substances and how they react Chemical substances are composed of matter Matter is the physical material of the universe; anything with mass that occupies space is matter Matter can take numerous forms Most matter is formed by unique arrangements of elementary substances called elements

Elements, Compounds, and Molecules An element can easily be defined as a substance that can not be broken down into simpler substances Millions of different materials in the world, all comprised of some combination of only 118 elements Similar to how the alphabet combines 26 letters to yield hundreds of thousands of words, elements bond in unique arrangements to give different molecules Molecules agglomerate to yield compounds

Mixtures Mixtures are combinations of substances in which the individuals substances retain their chemical identities and can be separated Can be homogeneous (uniform) or heterogeneous (non-uniform) Homogeneous mixtures are also referred to as solutions Most forms of matter we encounter are mixtures Food and Drink Air Medicines Toothpaste, lotion, etc.

Separation of Mixtures Substances in mixtures can be separated by differences in physical properties. Distillation: separation based on differences in boiling point Filtration: separation by differences in size

Separation of Mixtures Centriguation: separation based on differences in density, useful for colloidal suspensions

Separation of Mixtures Chromatography: separation based on differences in interaction between two substances ex. Chlorophyll and other pigments can be extracted from plant life using a solvent like acetone, and a coated solid (stationary phase). Compounds that interact weakly with the solid move further up, creating bands.

Molecules Are Comprised of Uniquely Arranged Atoms Molecules Are Comprised of Uniquely Arranged Atoms. Different Molecules Have Different Properties. H O H O

acetaldehyde (hangover) Small Molecular Differences Can Yield Vastly Different in Terms of Biological Interactions acetaldehyde (hangover) acetic acid carbon dioxide ethanol BLINDNESS!!! methanol

Small Molecular Differences Can Yield Vastly Different in Terms of Biological Interactions Relief of Morning Sickness Severe Limb Defects

Small Molecular Differences Can Yield Vastly Different in Terms of Biological Interactions C6H12O6 C6H12O6 Technically, glucose and fructose are the same. So is high fructose corn syrup really that bad for you???

Small Molecular Differences Can Yield Vastly Different in Terms of Biological Interactions

The Properties of Molecules Differ Vastly from those of the Atoms That Comprise Them Na (sodium metal) Cl2 (chlorine gas) Na+Cl-

Different atomic arrangements can change physical properties Carbon (graphite vs diamond)

Spatial Dimensions of Compounds Can Alter Properties Gold Nanoparticles Bulk Gold 5 nm 50 nm

Spatial Dimensions of Compounds Can Alter Properties 2 nm 12 nm CdSe quantum dots

Phases of Matter: Solids, Liquids and Gases Atoms tightly bound Fixed volume and shape (does not conform to container) A chemical is denoted as solid by labeling it with (s) S(s)

Phases of Matter: Solids, Liquids and Gases Atoms less tightly bound than solids Has a definite volume, but not definite shape (assumes the shape of its container) Denoted by (L) H2O (L)

Phases of Matter: Solids, Liquids and Gases Free atoms No shape, no definite volume Can be expanded or compressed (like engine piston) Denoted by (g) ; ex. O2 (g)