Atomic Theory and Mole Conversions

Law of multiple proportions

Different compounds have different whole number ratios of elements

Nucleus

Center of the atom containing protons and neutrons

Proton

Positively charged subatomic particle

Neutron

Subatomic particle with no charge

Electron cloud

Three-dimensional area where an electron is likely to be found

Electron

Negatively charged subatomic particle

Atomic number

Number of protons in an atom

Mass number

Number of protons plus neutrons in an atom

Neutral

Net charge is zero

Isotope

Atoms of the same element with different numbers of neutrons

Ion

Atom or group of atoms with a charge

Cation

Positively charged ion

Anion

Negatively charged ion

Isotope symbol

Element symbol with mass number as the left superscript and charge as the right superscript

Atomic weight

Weighted average of the masses of naturally occurring isotopes

Half-life

Time required for half of a sample to be used up

Mole

Unit used to measure the amount of a substance

Avogadro's number

Number of particles in a mole

Molar Mass

Mass in grams of one mole of substance

Democritus

First to name the atom

Lavoisier

Father of modern chemistry

Law of conservation of mass

Mass is conserved in chemical reactions

Dalton

Modern atomic theory

Thomson

Discovered existence of electron

Rutherford

Discovered the proton and nucleus

Bohr

Father of Quantum chemistry

Schrӧdinger

Electron clouds - specific location of electron is not known

Chadwick

Discovered the neutron

Atomic structure

Protons and neutrons in the nucleus, electrons in the electron cloud

Atomic number (Z)

Number of protons in an atom

Mass number (A)

Protons plus neutrons in an atom

Neutral atom

Net charge of 0, number of protons equals number of electrons

Ion

Charged particle

Cation

Positively charged atom

Anion

Negatively charged atom

Isotopes

Atoms with the same number of protons but different numbers of neutrons

Isotope symbol

Element symbol with mass number and charge

Hyphen notation

Element name and atomic weight

Atomic weight

Weighted average of naturally occurring isotopes

Half-life

Time for half of a sample to be used up

Mole conversions

Converting between moles and particles or grams

Avogadro's number

Number of particles in a mole

Molar mass

Mass of one mole of substance

Subscripts

Convert atoms to molecules or moles