Atomic Theory

s, p, d, f

the letters of the first four sublevels

atom

the smallest constituent unit of ordinary matter that has the properties of a chemical element

sublevels

divisions of the principle energy levels

energy levels

primary areas surrounding the nucleus in which electrons travel

wave mechanical model of an atom

credited to Schrodinger, DeBroglie, Heisenberg, and Hund

orbitals

areas on the energy levels and sublevels where electrons may be found

atomic theory

the scientific theory of the nature of matter, which states that matter is composed of discrete units called atoms

electron configuration

the arrangement of electrons on the atom in energy levels and sublevels

Thomson with the gas discharge tube

discovered electrons

n

energy level, sublevel variable

2n

orbital formula

2n²

electron formula

Chadwick with nuclear bombardment

discovered the neutron

Planck

discovered the Quantum Theory

Berzillius

was the first to use letters to represent the symbols for the elements

Democritus

first to use the term atomos, which means “not to be cut”

Rutherford with the golf foil experiment

discovered the nucleus of the atom and the proton

Millikan with the oil droplet experiment

measured the charge on the electron

Bohr

credited with the planetary model of the atom

the Aufbau principle

states that the electrons will occupy the energy level and sublevel of the arrangement with the lowest energy first

Lewis Dot Structure

shows the symbol of the element and its valence electron

protium, tritium, deuterium

the three isotopes of hydrogen

kernel electrons

electrons that include all electrons except for valence electrons

Hund’s Rule

states that orbitals of equal energy are each occupied by 1 electron before any orbital is occupied by 2 electrons, and all electrons in singly occupied orbitals must have the same spin

Dalton

revived the concept of atoms

Pauli exclusion principle

states that in order for two electrons to occupy the same orbital they must have opposite spins

isotopes

atoms with the same atomic number but different mass numbers

diamagnnetic

substances that are weakly repelled in a magnetic field

paramagnetic

substances that are weakly attracted in a magnetic field

ferromagnetic

elements that can become permanent magnets

Fe, Co, Ni

ferromagnetic elements

Proust

credited for the law of definite proportions

abundance of its isotopes

what the average mass of an element is based on

mass number

gives the numbers of protons and neutrons

all elements are made of atoms, atoms are indivisible and indestructible, atoms of different elements are different, compounds are formed by joining the atoms of two or more elements

main points of Dalton’s Atomic Theory (4)

atoms of the same elements aren’t exactly the same due to isotopes, atoms are divisible

disproven points of Dalton’s Theory

protium

0 neutrons, most abundant

deuterium

1 neutron, used in nuclear fission

tritium

2 neutrons, radioactive

Bohr’s Model

most accepted atomic model of the past

diagonal chart

shows the relationship between diagonal elements in the periodic table in that electrons fill orbitals in increasing quantum numbers

noble gas configuration

noble gas that precedes the element is considered its kernel electron and the remaining electrons are valence electroms

isoelectronic

atoms and ions with the same number of electrons