Atoms and the Periodic Table Crossword Puzzle

QUESTIONS LIST:

• nucleus : part of the atom comprising protons and neutrons (7)
• oxidation : process that causes reactive metals to discolour in air (9)
• mass : protons and neutrons have a relative _ of 1 (4)
• boron : the only non-metal group 3 element (5)
• chemical symbol : h is the _ of hydrogen (8,6)
• argon : gas used to stop cs and rb from oxidising in storage (5)
• lithium : metal harder than sodium and in the same group (7)
• positive : protons have a _ charge (8)
• sodium : na is the chemical symbol for _ (6)
• fluorine : non-metal with a mass number of 19 (8)
• electrons : negatively-charged sub-atomic particles (9)