SME
Grade 8 Science · Physical Science
The periodic table
Tap the periodic table to see how groups, periods and families of elements are arranged, and why.
Explore
Atomic number 8: 8 protons.
A nonmetal gas we breathe.
Assumptions
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Every element has its own kind of atom, with its own number of protons: the atomic number.
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The table lists the elements in atomic-number order, in rows (periods) and columns (groups).
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Elements in one group behave alike, so the table predicts how an element will react.
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Metals fill the left and middle, nonmetals the right; metalloids sit on the stair-step between.
Topic check
See what you know: 5 questions on this topic
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More problem types
Reading an element’s group and period
Use this for “In which group and period is element 17?”
Protons, neutrons and electrons from the card
Use this for “An atom has 8 protons and a mass number of 16. How many neutrons does it have?”
Metal, nonmetal or metalloid?
Use this for “Which of these elements is a nonmetal?”
Which group does it belong with?
Use this for “Which element reacts most like sodium?”