Chemistry: The Central Science Chapter 2

Atoms

The smallest units of an element that can combine with other elements

Subatomic particles

Electron, neutron, proton

Cathode ray: Thomson

Radiation originating from negative electrode (the cathode) that is attracted by negatively charged plates; "discovery" of electron

Oil-drop experiment: Millikan

Small drops of oil, which pick up extra electrons, fall between two electrically charged plates. Voltage of plates affected their rates of fall, which was measured and recorded.

Radioactivity

Spontaneous emission of radiation by atoms; gives further evidence that the atom has a substructure

Plum Pudding model: J. J. Thomson

Small electrons embedded in an overall positively charged sphere

Gold foil experiment: Rutherford

When a beam of alpha particles strikes gold foil, most pass straight through, but some are scattered; the reason for this is presence of a nucleus

Electronic charge

Magnitude of the charge of the electron (1.602*10^-19)

Atomic mass units (amu)

Used to measure mass of an atom

Angstroms

Used to measure dimensions of an atom

Atomic number

Number of protons in the nucleus of an atom; all atoms of a given element have the same atomic number

Mass number

Sum of the number of protons and neutrons

Isotopes

Atoms of same element that different in mass number/number of neutrons

Atomic weight

Average atomic mass; can be calculated by multiplying the atomic masses of various isotopes by their percent abundance and then adding them together

Mass spectrometer

Provides most direct and accurate means of experimentally measuring atomic (and molecular) weights

Metallic elements (metals) location on PT

Left and middle of Periodic Table

Nonmetallic elements (nonmetals) location on PT

Upper right side

Metalloids location on PT

Line separating metals and non-metals

Diatomic molecule

A molecule that contains two atoms

Chemical formula

Composition of a substance

Empirical formula

Relative numbers of atoms of each kind in a molecular substance (ex: C2H4 -> CH2)

Molecular formula

Actual numbers of each type of atom in a molecule

Ions

Charged particles that have gained or lost electrons

Cations

Positively charged ions (have lost electrons), metals

Anions

Negatively charged ions (have gained electrons), nonmetals

Ionic compounds

Electrically neutral combinations of cations and anions; so, usually contain both metallic and nonmetallic elements

Polyatomic ions

Atoms that are joined together but carry a net charge

Chemical nomenclature rules for cations

If can have more than one charge, the charge is written in roman numerals in parentheses -> Iron (II)
If formed from nonmetal atoms, their names end in -ium

Chemical nomenclature rules for anions

Monatomic anions are formed by replacing the ending of the name of the element with -ide -> H- is hydrIDE

Chemical nomenclature rules for polyatomic anions containing oxygen: An Example

ClO4- PERchlorATE (one more O atom than chlorate)
ClO3- ChlorATE ion (most common)
ClO2- ChlorITE ion (one O fewer than chlorate)
ClO- HYPOchlorITE ion (one O fewer than chlorite)

Oxyanions

Polyatomic anions containing oxygen

Chemical nomenclature rules for oxyanions containing H+

Add a prefix to "hydrogen" or "dihydrogen"

Chemical nomenclature rules for ionic compounds

Put name of cation before name of anion (Al(NO3)2 -> aluminum nitrate)

Chemical nomenclature rules for acids

If ends with IDE, the acid ends with IC and begins with HYDRO
If ends in ATE, ends with IC
If ends in ITE, ends with OUS

Chemical nomenclature rules for binary molecular compounds

Greek prefixes are used to indicate the number of atoms of each element

Prefixes for binary molecular compounds

Mono - 1
Di - 2
Tri - 3
Tetra - 4
Penta - 5
Hexa - 6
Hepta - 7
Octa - 8
Nona - 9
Deca - 10

Dalton's Atomic Theory

1. Each element is composed of extremely small particles called atoms
2. All atoms of a given element are identical to one another in mass and other properties, and are different from atoms of all other elements
3. Atoms are neither created nor destroyed in chemical reactions
4. Compounds are formed when atoms of more than one element combine

Organic Chemistry definition

Study of compounds that contain carbon

Hydrocarbons

Contain only carbon and hydrogen

Alkanes

Hydrocarbons in which each carbon atom is attached to four other atoms

Alcohol

A compound in which an H atom of a hydrocarbon is replaced by an OH (ends in -ol)