AP Chem Ch.2: History, Atoms, Molecules, Ions, Isotopes

Laws, experiments and stuff.

Law of Conservation of Matter

Matter cannot be created or destroyed.

Law of Definite Composition

2 chemicals combine ALWAYS in equal mass proportions. ( Ex. 22.9g of Na would ALWAYS combine with 35.4g of Cl, not with more or less.

Law of Multiple Proportions

It would always be the same thing or proportion under different conditions.

Dalton’s Atomic Theory

1. All matter is made out of tiny indivisible (at the time) particles called atoms.

2. Atoms of one element are the same, atoms of another element are different.

3. Compounds form in simple whole # ratios.

4. Reactions are just a rearrangement of atoms.

JJ Thomson

Using a cathode ray tube and a magnet, he discovered that atoms had a negatively charged particle called electron.

Plum Pudding Model

Created by JJ Thomson, it also stated that atoms are divisible, but not longer identifiable afterwards.

Ernest Rutherford

He shot Phosphorus particles into gold foil expecting them to just go through, instead some of them bounced off the gold foil. Concluded that the atom is mostly empty space, with an extremely dense + center, or Nucleus.

Bohr Model

Visual representation of an atom similar to the solar system. + Nucleus in the center with orbitals around it which are able to hold 2,8,8, and 2 e- in that order.

Heisenberg Uncertainty Principal

You never know the exact location of an e-

Ex: Trying to find the exact location of a helium balloon in the center of an empty, dark room.

Atomic Mass

Weighted average of all Isotopes of an element.

Isotopes

An atom of an element that has the same # of p+, but a different # of neutrons, therefore affecting its mass.

Mass # Equation

# protons + # neutrons

Atomic # Equivalents?

# protons or # electrons

Mass Spectrometry

Provides the following equation: Avg Atomic Mass= (Mass Isotope 1)(% Abundance) + (Mass Isotope 2)(% Abundance)

Metals properties

Malleable, form + Ions, shiny, lose electrons, and 3 or less valence electrons.

Nonmetals properties

Nonmalleable (brittle), form - ions, dull (not shiny), gain electrons, 5 or more valence electrons.

Binary/ Ionic Bonding

Metal + nonmetal (ex. NaCl)

Two Nonmetals=…

Covalent bond, or share electrons.