How to play Periodic Table Challenge
Periodic Table Challenge is a periodic table game for GCSE science. Before you start, choose your exam board: AQA, Edexcel or OCR Gateway. The game then uses the group numbers and relative atomic masses that your board prints on its own periodic table.
A round of ten mixes three kinds of question in a random order. Four times, the game names an element and you tap its cell on a blank periodic table. Three times, you pick the electron arrangement of an element, such as 2,8,1 for sodium. The other three ask for a relative atomic mass or the relative formula mass of a compound such as CO2 or Mg(OH)2.
The table gets bigger as the round goes on. Early placing questions use the first 20 elements. Later ones add the transition metals in period 4, and the last ones cover the main groups down to period 6. The harder start begins at the second level. Your best score is kept separately for each board.
A right answer scores 10 points, plus 5 for a quick one. If you tap the wrong cell, the game marks the right one and tells you its group and period. If you pick a wrong option, it tells you which mistake leads to that answer.
The science behind the periodic table
The periodic table puts the elements in order of atomic number, which is the number of protons in the nucleus. The rows are called periods and the columns are called groups. Elements in the same group have the same number of electrons in their outer shell, so they react in similar ways.
Electrons fill the lowest energy levels first. For the first 20 elements, the first shell holds 2 electrons and the next two shells hold up to 8 each. Sodium has 11 electrons, so its arrangement is 2,8,1. The number of shells is the same as the period number, and with groups numbered 1 to 7 and 0, the number of outer electrons in groups 1 to 7 is the same as the group number. AQA writes arrangements with commas, as in 2,8,1, and Edexcel uses dots, as in 2.8.1.
Relative formula mass, Mr, is the total of the relative atomic masses of all the atoms in a formula. The small number after a symbol tells you how many of that atom there are. For CO2 on the AQA table, Mr = 12 + (2 × 16) = 44. A bracket multiplies everything inside it, so Mg(OH)2 = 24 + 2 × (16 + 1) = 58.
The boards print their tables in different ways, and the game follows each one. AQA and Edexcel give whole numbers, apart from chlorine (35.5) and copper (63.5). OCR gives every mass to one decimal place, so on the OCR table CO2 comes to 12.0 + (2 × 16.0) = 44.0 and Mg(OH)2 comes to 58.3. AQA and Edexcel number the groups 1 to 7 and 0. OCR's data sheet numbers them 1 to 18 and adds the old numbers in brackets above the main groups.
You can see each full table on our periodic table by exam board page. There are separate pages for the AQA GCSE periodic table, the Edexcel GCSE periodic table and the OCR Gateway periodic table.
These ideas are in AQA GCSE Combined Science: Trilogy (8464, sections 5.1.1.7, 5.1.2.1 and 5.3.1.2) and Edexcel GCSE Chemistry (1CH0, 1.17, 1.19 and 1.43). Both ask students to write the electron arrangements of the first 20 elements.
Tips for the periodic table game
- Hydrogen and helium sit alone on the top row. Period 2 starts with lithium, so count along from there.
- Add up the numbers in an electron arrangement. They must come to the atomic number.
- Fill each shell before you start the next: 2, then 8, then 8 for the first 20 elements.
- In H2O there are two hydrogen atoms and one oxygen atom. The small number belongs only to the atom just before it.
- The atomic number is usually the smaller number in the cell. Using it in place of the relative atomic mass is one of the wrong options.
Relative masses have no unit, which is why the answers say (no unit). Don't add grams to them.
Use this in the classroom
Periodic Table Challenge suits Years 9 to 11 in chemistry or combined science lessons. It fits the start of the atomic structure topic and works again as revision before the exams.
Set the board to the one your students sit, so the masses match their exam paper. For a starter, name an element and ask the class to point to its group and period on a printed table before one student taps the answer on the board. The formula mass questions make a good plenary after a lesson on Mr.
Students play in the browser without an account. A timer-free practice mode helps anyone who wants to work slowly. The page for teachers lists more ways to use the games.
Similar games
Half-Life uses atomic number and mass number too, when you complete nuclear equations for alpha decay. You can find the others on the all games page.
Questions people ask
These are common questions about the periodic table at GCSE.
Why do AQA and OCR periodic tables give different relative atomic masses?
They round the values differently. AQA and Edexcel print whole numbers except for chlorine and copper. OCR prints every value to one decimal place, so magnesium is 24 on the AQA table and 24.3 on the OCR table. Use the table from your own board.
How do you work out the electron arrangement of an element?
Find the atomic number, which equals the number of electrons in a neutral atom. Put 2 in the first shell, then up to 8 in the second and 8 in the third. Calcium has 20 electrons, so it is 2,8,8,2.
How do you calculate relative formula mass?
Multiply the relative atomic mass of each element by the number of its atoms in the formula, then add the results. For H2O on the AQA table, that is (2 × 1) + 16 = 18.
Does the group number tell you the number of outer electrons?
Yes for groups 1 to 7, when the groups are numbered 1 to 7 and 0 as on the AQA and Edexcel tables. Sodium is in group 1 and has one outer electron. The elements in group 0 have full outer shells: helium has 2 and the others have 8.