Atomic Structure

The groups

1. Alkali metals 2. Alkaline earth metals 3. rare earth metals 3-12. transistion metals 13. boron group 14. carbon group 15. nitrogen group 16. oxygen group 17. halogens 18. noble gases

John Dalton

1803-atomic theory, law of multiple proportions

Dmitri Mendeleev

1869-Created the periodic table

JJ Thomson

1904-discovered the electron, plum pudding model

Ernest Rutherford

1911-Gold foil experiment, discovered nucleus

Niels Bohr

1913- discovered that electrons move around the nucleus in orbits called electron shells.

Henry Moseley

1913-Arranged the periodic table by atomic number instead of mass number

Democritus

400bc-First to name the atom, atomos

Isotopes

Atoms of the same element that have different numbers of neutrons

valence electrons

Electrons on the outermost energy level of an atom

Aristotle

Greek philosopher

Periods

Horizontal rows on the periodic table

Atom

Smallest particle of an element

Groups

Vertical columns on the periodic table

electron cloud

area around the nucleus of an atom where the atom's electrons are most likely to be found

What holds it together?

attractive force between +nucleus and -electron cloud repulsive force between electrons] repulsive force between protons

Schrodinger and Heisenberg

contributed to modern theory, said electrons do not travel in definite paths

hyphen form

element-mass

Nuclear form

mass number Symbol

Bohr Model

model of the atom in which electrons move rapidly around the nucleus in paths called orbits

Electron

negatively charged particle

Neutron

no charge

Quarks

particles of matter that make up protons and neutrons

Proton

positively charged particle

The number of electrons

same as the number of protons

atomic number

the number of protons in an atom

Mass number

the sum of the number of neutrons and protons in an atomic nucleus

average atomic mass

the weighted average of the atomic masses of the naturally occurring isotopes of an element