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| Question | Answer |
| In the early 1800s, there were only two ways to categorise elements. What were they? | Their physical and chemical properties Relative atomic mass |
| In 1817, how did Johann Döbereiner attempt to group similar elements? | Grouped elements into Döbereiner's triads |
| in 1863, English chemist John Newlands discovered the law of octaves. What was the law of octaves? | The chemist noticed that if he arranged the elements in order of mass, elements with similar chemical and physical properties appeared at regular intervals - every eighth element was similar |
| What was the flaw in the law of octaves? | The pattern broke down on the third row, with many transition metals (e.g. Fe, Cu and Zn) messing it up completely |
| How did Dmitri Mendeleev arrange the elements? | He arranged all the known elements by atomic mass, but he left gaps in the table where the next element didn't seem to fit. He also predicted the properties of undiscovered elements that would go in the gaps. When elements were later discovered, it showed that Mendeleev had got it right |
| In 1915, how did Henry Moseley arrange the elements? | Moseley arranged the elements according to increasing atomic number rather than by mass. He also added the nobel gases (Grou p0) which had been discovered in the 1890s |
| Glenn Seaborg made the final big change to the modern periodic table. What did he do? | He suggested how the f-block elements fit into the periodic table |
| 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 ________ ______. | The modern periodic table is arranged into PERIODS (rows) and GROUPS (columns). All the elements within a period have the same number of ELECTRON SHELLS. All the elements within a group have the same number of ELECTRONS in their OUTER SHELL. |
| TRUE OR FALSE: Elements across a period have the same physical and chemical properties | FALSE All the elements within a period have the same number of electron shells, resulting in REPEATING PATTERNS of physical and chemical properties across a period (periodicity) |
| TRUE OR FALSE: All the elements within a group have similar physical and chemical properties | TRUE All the elements within a group have the same number of electrons in their outer shell, meaning they have similar physical and chemical properties. |
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