Organisation of the periodic tableIB MYP Sciences: Revision notes
Section 1
Periods and groups
The periodic table arranges the elements in order of increasing atomic number. It is organised into:
- periods: the horizontal rows, numbered 1 to 7
- groups: the vertical columns, numbered 1 to 7 and 0 (also written 1 to 18)
Elements in the same group have similar chemical properties. Properties change gradually across a period.
Section 2
Metals, non-metals and metalloids
A thick staircase line runs down the right-hand side of the table.
- Metals are on the left and in the centre. Most elements are metals.
- Non-metals are on the right (and hydrogen at the top).
- Metalloids, such as silicon and germanium, lie along the staircase line. Their properties are between those of metals and non-metals; for example silicon conducts electricity only under some conditions.
Section 3
Position and electron configuration
The position of an element comes from its electron configuration.
- Outer electrons = group number
- Number of shells = period number
For example, sulfur is 2,8,6: it has 6 outer electrons (Group 6) and three shells (period 3). Metals tend to have few outer electrons (1 to 3), and non-metals tend to have more (4 to 7). The noble gases have a full outer shell.
Write the configuration first, then read off the group from the last number and the period from the number of shells.
Section 4
Mendeleev's table
In 1869, Dmitri Mendeleev arranged the elements known at the time in order of increasing atomic mass. He put elements with similar properties in the same column, even if that meant swapping a few elements around.
He also left gaps for elements not yet discovered and predicted their properties. When germanium was found in 1886, its relative atomic mass, colour, density and oxide matched his predictions for the missing element below silicon. This gave strong support for his table.
Mendeleev used atomic mass; the modern table uses atomic number.
Section 5
Common elements and symbols
Every element has a one- or two-letter chemical symbol. The first letter is always a capital and the second is lower case.
- H hydrogen, He helium, Li lithium, C carbon, N nitrogen, O oxygen
- F fluorine, Ne neon, Na sodium, Mg magnesium, Al aluminium, Si silicon
- P phosphorus, S sulfur, Cl chlorine, Ar argon, K potassium, Ca calcium
Some symbols come from Latin names: Na (natrium), K (kalium), Fe (iron, ferrum), Cu (copper, cuprum), Ag (silver), Au (gold), Pb (lead) and Sn (tin).
Co is cobalt but CO is a compound, carbon monoxide. Capital letters matter.
That's the notes covered.
Carry on to the next subtopic.
Exam questions on Organisation of the periodic table
- A school in Kuala Lumpur prints a large periodic table for its laboratory wall. Students use it to find the symbol, the group and the period of each element, and to decide whether an element is a metal, a non-metal or a metalloid.Describe where metals and non-metals are found in the periodic table.2 marks
- A student is making his own copy of the periodic table. He has a card for each element showing only its electron configuration, for example fluorine 2,7 and chlorine 2,8,7, and he places each card in the group and period that its electrons indicate.Explain why fluorine and chlorine are placed in the same group but in different periods.2 marks
- In 1869 Dmitri Mendeleev arranged the 63 elements known at the time in order of increasing atomic mass, but moved a few so that elements with similar properties fell in the same column. He also left gaps for elements that had not yet been discovered. He predicted that the missing element below silicon would have a relative atomic mass of about 72, a density of about 5.5 g/cm³, a grey colour and an oxide with the formula XO₂. In 1886 germanium was discovered. It has a relative atomic mass of 72.6, a density of 5.35 g/cm³, a grey colour and an oxide with the formula GeO₂.Describe how Mendeleev organised his periodic table, and why he left gaps in it.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).