College Chemistry

J.J. Thomson

discovered electrons in the late 1800's

discovered cathode rays, plum pudding model

Pure Substances

a substance made up of only one type of atom/molecule

Elements

substances that contain only 1 kind of atom and cannot be broken down any further through chemical reactions

Atom

smallest possible particle of an element that still retains the properties of that element.

Compound

pure substances that contain more than one type of element bonded in fixed proportions

Molecule

2 or more atoms joined in specific shape by chemical bonds. smallest particle of a compound that still has the properties of that compound

Mixtures

substances that have different compositions and so varying properties.

homogeneous

similar compositions throughout

heterogenous

very different compositions

Isotopes

atoms with the same atomic #, but different #'s of neutrons

Natural abundance

percentage of atoms occurring as a given isotope

Periods

rows on the periodic table

Groups

columns on the periodic table

Polyatomic element

ion with a group of multiple atoms with a charge

Ions

atoms or molecules with a charge

Ionic compounds

compounds made up of ions that can be single atom ions or polyatomic ions and solids that contain cations and anions in balanced whole number ratios

Chemical bond

strong attractive force between atoms that results from the interactions between charged particles (protons and electrons)

organic compounds

carbon containing compounds

Hydrates

Ionic compounds that have water molecules incorporated into their structures.

Nuclear Theory of the Atom

-Most of the atom's mass and all of its positive charge are in the nucleus.

-Most of the volume of the atom is empty space occupied by negatively charged electrons

- -electrons are outside nucleus & +protons are inside nucleus to = a neutral atom

Atom

the smallest identifiable unit of an element

Democritus

Greek philosopher that said all matter is made of tiny particles called "atomos" or atoms (indivisible)

Dalton's Theory (early 1800s)

-each element is made of indestructible particles called atoms

-All atoms of a given element are identical in mass and properties

-atoms combine in simple whole # ratios=compounds

Thomson (early 1900s)

cathory tube experiment discovered the electrons

What model was Thomson's?

plum pudding-with particles randomly floating around

Rutherford (1911)

Gold foil experiment. Discovered the nucleus

What gives the atom its identity?

number of protons

What keeps the nucleus together?

number of neutrons-strong nuclear force

What is an isotope?

Atoms of the same element that have different numbers of neutrons

What is an ion?

an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.

What are alkali metals?

Group 1 (-H) highly reactive, do not occur freely in nature

What are alkaline earth metals?

Group 2

What are the inner transition metals?

elements that appear below the main body of the periodic table

What are halogens?

Group 17 very reactive nonmetals

What are noble gases?

Group 18, stable elements

Millikan experiment

measured elctron charge by oil drop expirament