Download 2.2 The Periodic table and Chemical Properties

2.2 The Periodic
Table and Chemical
Properties
History
• Chemists began looking for a way
to organize their observations of
elements
• In 1867, Dmitiri Mendeleev wrote
down every element on a card
• It included density, color,
melting point, and boiling point
• As Mendeleev did this he began
to notice holes within the table
and predict properties of other
elements
History
• Born : 1834
Died : 1907
Nationality : Russian
• Occupation : Chemist
• Dmitri Mendeleev brought order to the chaos of chemistry by
asserting his periodic law, which states that the elements
arrange themselves according to their atomic number and
their chemical properties
The Periodic Table
By the end of the lesson you should be able to
• Know how the elements are listed in rows by increasing order
of Atomic number
• Rows are arranged in such a way that elements with similar
properties line up in vertical columns
• Each element in the table is recorded using its name, symbol,
atomic number, atomic mass, and common ion charges
The Periodic Table
• Two families of metals are the alkali metals and the alkaline
earth metals
• Two families of non-metals are the halogens and the noble
gases
The Periodic Table
• Is a chart that organizes the elements according to their
physical and chemical properties.
• The periodic table gives each element’s name, symbol, atomic
number, atomic mass, and ion charges
The Atomic Number
• This is the number of protons in the nucleus of each atom of
an element
• It is always a whole number (they run in a pattern)
Atomic Mass
• This is the average mass of an atom of an element.
• It is always written as a decimal number and is measured in
atomic mass unit (amu)
Ion Charge
• This happens to an element when it gains or loses electrons
• Any electrically charged atom is called an ion
• The electrons make it more negative because they are negative
Ion Charges
• Some elements have multiple ion charges
• These form in more than one way
• Pattern:
• Elements on the left hand side are usually positive ions
• Elements on the right hand side, except for the last column,
generally form negative ions
• Elements that are in the same column often form ions with
the same ion charge as other elements in that column
How is it set up?
• Elements are listed horizontally according to their
atomic number (number of protons).
• Periods are the horizontal rows of elements.
How is it set up?
• Elements are listed vertically according to their
chemical properties.
• Groups or Families are arranged vertically.
• Non-Metals are found on the right side of the staircase
• Metals are found on the left side of the staircase
• Metalloids (have some properties of both metals and nonmetals) are on the staircase
Metal, Non-Metals, and
Metalloids
Groups
Alkali Alkaline
Metals Earth
Metals
Noble
Gases
Halogens
Alkali Metals
• Highly reactive
• Reactivity increases as you go down the group.
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React with both oxygen and water.
Soft
Low melting points
Have a +1 ion charge
Alkaline Earth Metals
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Less reactive than alkali metals
Burn in air if heated
Produce bright flames and used in fireworks.
Will react with water, but not as vigorously as alkali metals
Have a +2 ion charge
Halogens
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Non-metals
Highly reactive
F and Cl are gases at room temperature
Br is a liquid and I is a solid
F is the most reactive and I is the least
Have a -1 ion charge
Noble Gases
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Non-Metals
Most stable and unreactive elements
They are colourless, odourless gases
Ar and Ne are used in light fixtures
“Royal”
Have a 0 ion charge (don’t make ions)