Periodic Patterns
How the periodic table is built: elements ordered by atomic number, groups and periods, the story of how Mendeleev developed the table, and the split between metals and non-metals.
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The periodic table
The periodic table organises all the elements. In the modern table, elements are arranged in order of atomic number. Columns are called groups, and elements in the same group have similar chemical properties because they have the same number of electrons in their outer shell. Rows are called periods.
Words for the table
Learn these four terms before you explore the patterns.
Metals and non-metals
The table is split between metals and non-metals.
Explain it by outer electrons
To reach the top grades, explain why a group shares properties in terms of outer electrons, and describe how Mendeleev left gaps and predicted properties so that later discoveries confirmed his table.
Match the feature to its meaning
- a group
- a period
- atomic number
- outer electrons
- a column of elements with similar properties
- a row across the periodic table
- the number of protons, used to order the table
- the electrons that decide chemical properties
Match the term to its meaning
- Mendeleev
- metal
- non-metal
- noble gas
- the scientist who left gaps for undiscovered elements
- an element that forms positive ions
- an element on the right of the table
- an unreactive element in Group 0
How is the table ordered?
How are elements arranged in the modern periodic table?
- By atomic number, the number of protons.
- By the number of neutrons.
- In alphabetical order.
- By relative atomic mass, as Mendeleev did.
Properties of metals
Select the TWO properties that are typical of metals.
- They conduct electricity.
- They form positive ions.
- They are always gases.
- They sit on the right of the table.
Order the discovery
Put the development of the periodic table in order, earliest first.
- Elements are first arranged by atomic weight
- Mendeleev leaves gaps and predicts missing elements
- The predicted elements are later discovered and fit
- The modern table is arranged by atomic number
Summarise the table
The modern periodic table arranges elements by their atomic _____. A column is called a _____, and elements in it have similar _____. A row is called a _____. Mendeleev left _____ for elements not yet discovered.
Count the outer electrons
Chlorine is in Group 7 of the periodic table. How many electrons does it have in its outer shell?
How the table is ordered
Tap the TWO statements that are TRUE.
- Elements in the same group have similar properties
- The periodic table is ordered by atomic number
- A period is a column of the table
- Metals form negative ions
- Noble gases are very reactive
Metal, non-metal, or noble gas?
Decide how to classify each element.
- Iron, which conducts electricity and forms positive ions
- Oxygen, found on the right of the table
- Argon, in Group 0 and very unreactive
Explain the development
Explain how Mendeleev arranged the early periodic table and why it later became accepted. Cover how he ordered the elements, why he left gaps, and what happened when new elements were discovered.
- Explain how Mendeleev ordered the elements
- Explain why he left gaps and made predictions
- Explain why the table became accepted