Reading a box on the J258 sheet
The top number in a box is the atomic number, which tells you how many protons an atom has. The big letters are the symbol, with the name in small print under it. The number at the bottom is the relative atomic mass.
The columns carry two sets of labels. The numbers 1 to 18 run across the whole table. The main groups also have (1) to (7), and (0) over the noble gases.
Same table as OCR Gateway
OCR prints an identical periodic table for its two GCSE chemistry courses. If a friend studies Gateway, their OCR Gateway table matches this one.
Both give masses to one decimal place: iron is 55.8 and potassium is 39.1.
Elements with no mass on this sheet
Of the elements on the sheet, 67 have a mass. The rest have a box that stops at the name: technetium, polonium, astatine, radon, and every element in period 7 that OCR shows.
OCR does not give the lanthanides a box each. It puts a single box marked 57-71 in their place, and one marked 89-103 for the actinides.
A formula mass with OCR numbers
Calcium carbonate, CaCO3, is the main part of limestone and chalk. It has one calcium atom, one carbon and three oxygen.
- Ca: 1 × 40.1 = 40.1
- C: 1 × 12.0 = 12.0
- O: 3 × 16.0 = 48.0
- Add them: 40.1 + 12.0 + 48.0 = 100.1
With AQA's whole numbers the same sum gives 100. Compare all the boards on the periodic table hub. Teachers will find classroom notes on our teachers page.
OCR 21st Century periodic table questions
Which OCR course uses this periodic table?
GCSE Chemistry B (Twenty First Century Science), code J258. OCR prints the same table for Chemistry A, the Gateway course.
What is the relative formula mass of sodium chloride with OCR numbers?
Sodium is 23.0 and chlorine is 35.5, so NaCl comes to 58.5.
Why does the OCR table skip some elements?
OCR leaves out the lanthanides, the actinides and elements 113, 115, 117 and 118. It also leaves some boxes without a mass.