CH110A

Chapter 2 Notes

Chemistry is another language. Getting comfortable with the NOMENCLATURE of chemistry is half the battle.

Lavoisier's Law of Conservation of Mass

Mercury oxide was heated to produce liquid mercury and oxygen gas. He found that the total mass of PRODUCTS = total mass of REACTANTS.

Dalton's Law of Multiple Proportions

An experiment like the electrolysis of water shows us that when elements combine, they do so in the ratio of whole numbers.

The Atom

atomic mass unit- an arbitrarily accepted unit equal to 1/12 the mass of a carbon-12 atom

atomic mass- mass of an element, accounting for the percentage of each naturally occurring ISOTOPE

atomic number (Z)- number of protons in an atom (and electrons for a neutral atom)

mass number (A)- number of protons plus neutrons in an atom

The Periodic Table

Mendeleev- noticed that certain properties had trends and repeated themselves from element to element to element, arranged elements with similar properties in rows (PERIODS) and columns (GROUPS)

metals, nonmetals, and metalloids (oh, my!!)

Compounds

chemical formula- shows actual number of each type of element in a compound....order of elements may give some hint at how they are connected

empirical formula- the smallest whole number ratio of elements in a compound (ex- CO₂ is the chemical formula for carbon dioxide, but also the empirical formula for C₂O₄ and C₃O₆)

structural formula (Chem CDX Representing Substances)

Naming compounds

Binary compounds- which element goes first?

Prefixes and suffixes (see Tables 2.3 and 2.4)

Ions

CATIONS ("cat-eye-ons") are POSITIVELY charged atoms or groups

ANIONS ("an-eye-ons") are NEGATIVELY charged atoms or groups

Hydrates- compounds which exist with one or more molecules of water in the FORMULA UNIT (not a topic we will discuss in depth)

Acids, Bases, Salts

Acid plus base makes salt plus water

Arrhenius definitions: Acids dissolve in water releasing H⁺; bases dissolve in water releasing OH^-

Bronsted-Lowry definitions: Acids are proton donors; bases are proton acceptors.

Lewis definitions: Acids are electron pair acceptors; bases are electron pair donors.

Isomers have the same formula but different structures

Structural isomers have the atoms connected differently

Geometric isomers have atoms arranged differently around a double bond

Organic compounds- compounds based on carbon

Alkanes- contain only C and H- general formula C_nH_2n+2
Example- octane...When burned in an ideal world, alkanes produce only water and carbon dioxide....unfortunately, the world we live in is not ideal
CYCLIC alkanes have the carbon chain in a ring, and have the general formula C_nH_2n
Become comfortable with the "line drawing" shorthand of structural formulas

Alkenes- contain only C and H with at least one double bond in the carbon chain- general formula C_nH_2n
Example- ethylene used to make polyethylene bottles

Alkynes- contain only C and H with at least one triple bond in the carbon chain- general formula C_nH_2n-2
Example- acetylene used for welding

Functional Groups- groups of atoms seen in many compounds....these groups of atoms give the resulting compounds similar properties and/or reactivity (See Table 2.7)

Alcohols- general formula R-OH, where R is any organic group
Example- ethanol (drinking alcohol), methanol (wood alchohol which causes blindness and death at very low dosages), isopropanol (rubbing alcohol)

Ethers- general formula R-O-R', where R and R' may be the same organic groups or different
Example- engine starter and anaesthetics of old

Aldehydes- general formula R-CO-H, where there is an oxygen with a double bond to C attached to a single R group (and an H)
Example- formaldehyde

Ketones- general formula R-CO-R', where there is an oxygen with a double bond to C attached to two (same or differing) R groups
Example- acetone (paint thinner/nail polish remover)

Carboxylic acids- general formula R-COOH, where there is an oxygen with a double bond to C and an OH attached to the same C
Example- acetic acid a.k.a. vinegar

Esters- general formula R-COOR', where there is an oxygen with a double bond to C and an OR' group attached to the same C
Example- almond and vanilla extract

Amines- general formula R-NH₂
Example- ammonia a.k.a. Windex or glass cleaner

Aromatics- alternating single and double carbon-carbon bonds