FEMALE STUDENT: The number of protons in each atom of an element. MALE PROFESSOR: Right.Well, early versions of the periodic table had gaps. Missing elements.Every time you have one more proton you have another element,and then — oops — there'd be an atomic number for which there was...
The first discovery that had to do with what goes on in nuclei was radioactivity, which is caused by particles being shot out of the nucleus. It was known that a great deal of energy is locked up in the nucleus, but, until just before the outbreak of the Second World War, there was...
Chemistry is a part of science that involves elements and compounds which can be examined to better understand their structures, properties, behavior and any relevant changes the compound may experience as a result of a chemical reaction. Chemist...
If you know where a certain element sits in the table, and you know a little bit about the properties of the elements above, below, and either side, you can often figure out what the properties of that element will be.How do atoms make molecules and compounds? Atoms are a bit like ...
1839: French physicist Alexandre-Edmond Becquerel (father of radioactivity pioneer Henri Becquerel) discovers some metals are photoelectric: they produce electricity when exposed to light. 1873: English engineer Willoughby Smith discovers that selenium is a particularly effective photoconductor (it's later ...