how did Mendeleev arrange the elements in the periodic table
- increasing atomic mass
- similar chemical properties in vertical groups
- left gaps predicting properties of undiscovered elements
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how is the modern periodic table arranged
- ascending atomic number
- similar chemical properties (groups)
- rows called periods
what do groups show
- how many electrons are in the outer electron shell
- eg group 1, one electron in outer shell
- group 0- 8 electrons in outer shell full
what do periods show
- in rows
- shows number of electron shells
- eg sodium 2,8,1 three electron shells
electron shell order
2,8,8
What does the Group Number tell you about the electrons in an element?
Group Number = Number of electrons in outer energy level / shell.
How were elements in the early periodic tables arranged?
By atomic weights
Who designed a Periodic Table that left gaps for undiscovered elements?
Mendeleev
Q. Where are metals found on the Periodic Table?
Q. Where are the non-metals on the Periodic Table?
- Metals are on the Left-Hand Side of the Periodic Table
- Non-metals are on the Right-Hand Side of the Periodic Table
What are the elements in Group 0 called?
Noble Gases
In terms of electron arrangement, explain why noble gases are unreactive.
They have a full outer shell of electrons. (Helium has 2 electrons in outer shell, all other noble gases have 8 electrons in outer shell).
How does the boiling point of noble gases change as you go down the group?
It increases
What is the name given to the elements in Group 1 of the Periodic Table?
Alkali Metals
What happens the the reactivity of alkali metals as you go down the group?
Reactivity Increases
What are the elements in Group 7 of the Periodic Table called?
Halogens
Which group of elements form molecules made up of pairs of atoms?
The Halogens (Group 7)
Separate Q. Compare transition metals and alkali metals in terms of the following properties:
a )Strength
b) Hardness
c) Melting Points
d) Density
e) Reactivity
a) Transition metals are stronger (or vice versa)
b) Transition metals are harder (or vice versa)
c) Transition metals have higher melting points (or vice versa)
d) Transition metals have a higher density (or vice versa)
e) Transition metals are less reactive (or vice versa)
Separate Q. Name the metals that can have ions with different charges.
Transition Metals
(e.g. an iron ion can be Fe2+ or Fe3+)
Separate Q. Name the metals that make useful catalysts.
Transition metals
Separate Q. Name the metals that make coloured compounds.
Transition Metals
