Chem 11Chem 11

History• Russian scientist Dmitri Mendeleev taught

chemistry in terms of properties.

• Mid 1800 - molar masses of elements were known.

• Wrote down the elements in order of increasing mass.

• Found a pattern of repeating properties.

Mendeleev’s Table• Grouped elements in columns by similar

properties in order of increasing atomic mass.

• Found some inconsistencies - felt that the properties were more important than the mass, so switched order.

• Found some gaps.• Must be undiscovered elements.• Predicted their properties before they were

found.

The modern table• Elements are still grouped by properties.

• Similar properties are in the same column.

• Order is in increasing atomic number.

• Added a column of elements Mendeleev didn’t know about.

• The noble gases weren’t found because they didn’t react with anything.

• Horizontal rows are called periods

• There are 7 periods

• Vertical columns are called groups.

• Elements are placed in columns by similar properties.

• Also called families

Similarities

• Groups: vertical columns – Have similar properties because they have

same number of electrons in outer shell

1A

2A 3A 4A 5A 6A7A

8A

• The elements in the A groups are called the representative elements

The group B are called the transition metals

These are called the inner transition elements and they belong here

• Group 1 are the alkali metals

• Group 2 are the alkaline earth metals

• Group 7A is called the Halogens

• Group 8A are the noble gases

Metals: To the left of the staircase line

• Physical Properties:Luster (shiny)Good conductorsHigh densityHigh melting pointMalleable

• Chemical Properties:

Easily lose electronsCorrode easily (ex:

rusting or tarnishing)Low

electronegativity

Non metals: to the right of the staircase line

• Physical Properties:DullPoor conductorBrittleNot malleableLow density and

melting point

• Chemical Properties:Tend to gain electronsHigh electronegativity

Metalloids: along the staircase line

• Solids• Shiny or dull• Malleable• Conduct heat and

electricity better than non metal but not as well as metals

Colour your periodic table

• Draw the staircase in with a dark line• Put the group numbers (A and B) at the top of

each group• Metals = 1st color• Metalloids = 2nd color • Non-metals = 3rd color

*Periodic table in the back of the book is colored this way!