Atomic Theory Flashcards
The Greek who proposed the idea of a fundamental particle that was indivisible
Democritus
460 BC
The father of modern chemistry who defined the concept of the element named oxygen and hydrogen and identified the need for the conservation of mass
Antoine Lavoisier
second half of the 1700s
In a close system the total mass of the reactants or starting materials must be equal to the mass of the products
The law of conservation of mass
Substances combine in precise proportions (e.g. H2O is two atoms of hydrogen and one atom of oxygen)
The Law of Definite portions
1 all material is composed of atoms which are indivisible
2 all the atoms of a given the element are alike in mass and all other respects
3 compounds are formed by combinations of two or more different types of atoms
4 A chemical reaction is a rearrangement of atoms
John Daltons Atomic Theory
(1808)
- 4 postulates
The Russian chemist who produced the first modern periodic table
Dmitri Mendeleev (1860s)
A tabular arrangement of the elements according to their atomic mass
Periodic table
The mass of all protons and neutrons that make up an element
Atomic weight
A German chemist who developed the Bunsen burner, spectroscope, discovered rubidium and caesium, and investigated the emission spectra of elements
Robert Bunsen
1850s
Positively charged particle found in the nucleus of an atom
Proton
A particle found in the nucleus of an atom that has no charge.
Neutron
A negatively charged particle in an atom, which moves in space around the nucleus
Electron
The total number of protons in the nucleus of an atom
Atomic number
The total number of protons and neutrons in the nucleus of an atom
Mass number
Atoms with the same atomic number but different mass number.(atoms with the same number of protons but a different number of neutrons)
Isotope
A New Zealand born scientist whose experiments with gold foil and alpha particles led to the modern idea of the atom: mostly empty space, positively charged nucleus and negative charges on the outside of the nucleus.
He won the Nobel Prize in physics (1908) for his work in nuclear physics. He identified alpha and beta particles and split the atom.
Ernest Rutherford
Early 1900s
Stream of particles and/or energy from a radioactive source
Radiation
The spontaneous disintegration of unstable of unstable atomic nuclei accompanied by the emission of alpha, beta or gamma particles
Radioactivity
The first woman to win two Nobel prizes in two different categories of science. Awarded for her work in radioactivity.
Marie Curie
Early 1900s
Two neutrons and two protons emitted when an unstable nucleus decays.
Alpha particle
An electron that is emitted when an unstable nucleus decays
Beta particle
A high frequency region of the electromagnetic spectrum emitted when a stable nucleus decays
Gamma radiation
A reaction that is self-sustaining as a result of one step starting another step
Chain reaction
The time taken for half of an isotope to decay
Half life
The splitting of a nucleus into smaller nuclei
Nuclear fission
The branch of medicine that uses radioactive isotopes to diagnose, manage and treat diseases
Nuclear medicine
The treatment of cancer by radiation
Radiotherapy
The fundamental particle of matter made up of protons neutrons electrons
Atom
