Across
- 4. German chemist Johann Döbereiner made a key discovery while studying properties of the elements in the early 1800s. He noticed groups of elements, like chlorine, bromine (35), and iodine (53), with _______ properties
- 6. The spaces left blank in Mendeleev's periodic table were for _______ elements that he predicted would be found in the future.
- 9. In ________, an atom could have an infinite number of energy levels, but so far we know only of elements with up to seven energy levels.
- 12. The discoveries of gallium (31) and germanium (32) proved that Mendeleev was _________.
- 13. The row that a certain element is ______ in also designates the energy level of its valence electrons.
- 16. Each period represents an _______ level.
- 17. A family, or group, is a set of elements in the same _______ on the periodic table.
Down
- 1. Scientists call a row on the periodic table a ______.
- 2. The most striking features of Mendeleev's periodic table were the _______ spaces that he left between some elements
- 3. Most importantly, each element in the group has the same number of ______ electrons, which are the electrons in the outermost energy level of a neutral atom.
- 5. In 1869, Russian chemist Dmitri Mendeleev organized the elements in a table much like our ______ periodic table
- 7. In 1865, Newlands developed his law of ________, which states that when elements are arranged by atomic mass, the properties of every eighth element are similar.
- 8. Moseley recognized that he was able to use a new technique called X-ray ________ to determine the atomic number for each element
- 10. Scientists started to notice repeating patterns when they arranged the elements in order by increasing atomic mass. This repeated pattern is called _______.
- 11. The most updated versions of the periodic table include all the elements through ______ number 118.
- 14. The arrangement of the _________ table relates to the structure of the atoms themselves.
- 15. ________ Henry Moseley made an important discovery in 1914