Mendeleev looked at the element Silicon. He knew the element below it was missing. He named this missing element 'Eka-Silicon' (meaning 'first-silicon'). He predicted: 1. Its atomic mass would be about 72. 2. It would be a solid metal. 3. It would combine with oxygen to form a compound with the formula MO2. Years later, a scientist named Winkler discovered 'Germanium'. It had an atomic mass of 72.6, was a solid, and formed the compound GeO2. Mendeleev was exactly right!