Across
- 2. last element in the first row
- 5. atoms with the same atomic number but have different numbers of neutrons
- 6. A negatively charged particle in an atom
- 8. usually is reported in grams and kilograms
- 9. the sum of the atomic masses
- 10. Things that we change in an experiment
Down
- 1. Is made up from the atoms of two or more elements, chemically combined
- 3. At least two atoms, identical or not, chemically attached to each other
- 4. An element with the atomic number 8
- 7. the name of this lesson
- 9. unit for measuring a large number