Across
- 1. Which element has a zero valency?
- 3. Mendeleev Who invented the periodic table?
- 5. What do horizontal rows represent?
- 6. Which element has the lowest electronegativity?
Down
- 1. row What is a period on the periodic table?
- 2. 17 What are the halogens?
- 4. What do vertical columns represent?