Lesson 2 of 6

Organising the elements

Goal: Describe how the periodic table is arranged.

Puzzles for this lesson

Word search0 of 8 found Crossword0 of 34 letters

An old desk covered with blank cards laid out in rows and columns. Two spaces have been left empty

The periodic table lists every element in order. Elements that behave alike line up in columns.

Dmitri Mendeleev published his periodic table in 1869. He wrote each known element on a card and put the cards in order of the mass of their atoms.
He lined up elements with similar properties in the same column.
He left gaps for elements that nobody had found yet, and predicted what they would be like.

GroupA column. The elements in a group have similar properties.

PeriodA row. Period 1 is the top row.

Today the table holds 118 elements, in order of atomic number. The main groups are numbered 1 to 7 and 0. Some tables number every column from 1 to 18: on those, Group 7 is 17 and Group 0 is 18.

Your turn

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Check yourself

I can say what Mendeleev did.I can point to a group and a period.

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Key words in this lesson

Periodic table A chart of all the elements, arranged in rows and columns

Group A column of the periodic table

Period A row of the periodic table

Atomic number The number that gives an element its place in the periodic table

For teachers: AQA 3.5.3 · Pearson Edexcel 16.4, 16.5, 17.2 · Cambridge 7Cm.02