In the early 1800s, there were only two ways to categorise elements. What were they?

In 1817, how did Johann Döbereiner attempt to group similar elements?

in 1863, English chemist John Newlands discovered the law of octaves. What was the law of octaves?

What was the flaw in the law of octaves?

How did Dmitri Mendeleev arrange the elements?

In 1915, how did Henry Moseley arrange the elements?

Glenn Seaborg made the final big change to the modern periodic table. What did he do?

Complete the sentences:
The modern periodic table is arranged into ________ (rows) and ________ (columns). All the elements within a period have the same number of ___________ _________. All the elements within a group have the same number of ___________ in their ________ ______.

TRUE OR FALSE:
Elements across a period have the same physical and chemical properties

TRUE OR FALSE:
All the elements within a group have similar physical and chemical properties