Date: Sept 2
Sections 5.5,

Elements & the Periodic Table

The Periodic Table

The periodic table is a chart of all the elements based on increasing atomic number (number of protons in the nucleus). Elements with similar physical and chemical properties are listed in columns. This is why the table is refered to as periodic. Chemicals in these columns are refered to as families of elements.

Elements in the royal blue colour are classified as metals
Elements in the aqua blue colour are the nonmetals
The purple diagonal band are labeled the metalloids
The lavender row are called rare earths or Lanthanides
The bottom pink row are transuranic elements called the Actinides

There are five "common-named" families of elements

Alkali metals --------------- column I
Alkaline Earth metals ----- column II
Halogens -------------------- column VII
Noble gases ----------------- colum VIII
Coinage metals ------------- column IB

You should be able to find these elements on the periodic table and know the names of these elements.

Elements and Atomic Structure: Bohr Diagrams

All atoms are made up of protons, neutrons (found in the nucleus) and electrons (found in shells surrounding the nucleus).

Particle Mass Charge Where Found

Proton

Neutron

Electron

Bohr diagrams you should be familiar with. I would expect you to be able to sketch a Bohr diagram for the the first twenty elements.

Isotopic Symbols

Isotopic symbolism is used to show and indicates the mass number (written on top) and the number of protons (found on the bottom).

If the atomic number is subtracted from the mass number the number of nuetrons can be calculated.

Ions and Ion Formation

What is an ion? An ion is formed when an atom either gains or losses an electron(s). If an electron is gained the charge on the atom decreases. For example, when the hydrogen atom gains one electron its charge changes from 0 (zero) to -1 (negative one); an algebraic decrease. When the sodium atom loses 1 electron its charge changes from 0 to +1 and increase in charge. Atoms that lose electrons have their postive charge value increased.

Which class of elements gain electrons? Answer == nonmetals

Which class of elements lose electrons? Answer == metals.

Metalloids have the ability do go both ways, in other words they can behave as either a metal or a nonmetal depending on the chemical enviroment.

> The ionic charge of an atom is the numerical value of the electric charge eithr plus or minus.

Definitions

Valence Electron(s):
The electron(s) found in the outer shell of an atom. See Bohr diagrams for the exact numbers. The outer most shell of an atom is called the valence shell.
Two important facts

The number of valence electrons correlates to the number of electrons that can be gained or lost by the atom. The atom will either lose all of its valence electrons (metals) or gain an appropriate number so that the last shell has a total of eight electrons (nonmetals).
The column number of the element will tell you how many valence electrons are present in the atoms outer shell (representative elements only).

Example: calcium is in Column II. It has 2 valence electrons and being a metal will lose both of them to form a Ca⁺² ion.
Sulphur is in Column VI. It has 6 valence electrons and being a nonmetal, will gain 2 electron to fill its valence shell to 8 to become the S^-2 ion.

Cations
Atoms that have lost an electron(s) and are positive are called cations

Anions
Atoms that gain electron(s) and become negative are called anions

Assignment #5 Working with Valence States

This assignment is to be handed in by Sept 12
Just click the beaker to get the assignment.