Atomic structure and the periodic table Flashcards
Elements
A pure substance containing 1 atom.
Compound
2 or more atoms that are chemically bonded
Mixture
2 or more atoms that are not chemically bonded
Electron structure
2,8,8
Distillation
Used to separate liquids with different boiling points
Dimitri Mendeleev
Successfully made the periodic table of elements
John newlands
He ordered the elements by atomic weight until Mendeleev proved him wrong
Noble gases
The noble gases are a group of elements in the periodic table. They are located to the far right of the periodic table and make up the eighteenth column. Elements in the noble gas family have atoms with a full outer shell of electrons.
Group 1
All the Group 1 elements are very reactive. They must be stored under oil to keep air and water away from them. When they react with water, Group 1 elements form metal hydroxides which are alkaline
Halogens
The non-metal elements in Group 7 – known as the halogens – get less reactive as you go down the group. This is the opposite trend to that seen in the alkali metals in Group 1 of the periodic table.
Isotopes
An isotope is one of two or more species of atoms of a chemical element with the same atomic number and position in the periodic table and nearly identical chemical behavior but with different atomic masses and physical properties. Every chemical element has one or more isotopes.
Plum pudding model
In 1897, J. J. Thomson discovered the first subatomic particle, the electron, while researching cathode rays. To explain the neutrality of atoms, Thomson proposed a model of the atom in which negative electrons are scattered throughout a sphere of positive charge.
Nuclear model
In 1909 Ernest Rutherford designed an experiment to test the plum pudding model. In the experiment, positively charged alpha particles were fired at thin gold foil. Most alpha particles went straight through the foil. But a few were scattered in different directions.
planetary model
Niels Bohr adapted Ernest Rutherford’s nuclear model. Bohr did calculations that led him to suggest that electrons orbit the nucleus in shells. The shells are at certain distances from the nucleus. The calculations agreed with observations from experiments.
Rutherford-Bohr atomic model
In 1932 James Chadwick found evidence for the existence of particles in the nucleus with mass but no charge. These particles are called neutrons. This led to another development of the atomic model, which is still used today.
