Answer:
Bismuth
Explanation:
In 1869 Mendeleev published his first Periodic System ending with Bismuth.
In 1871 he updated his system to end with Uranium.
Answer:
76
Explanation:
Alpha decay is one of the most basic forms of radioactive decay. It has an atomic mass of 4 and a proton number of two.
Undergoing an alpha decay will decrease the atomic mass by four and the atomic number by two.
In this particular question, we are particular about the atomic number. The atom has an atomic number of 78. So taking 2 off this gives 76
Answer:
The arrangement of the periodic table leads us to visualize certain trends among the atoms.
Elements are arranged from left to right and top to bottom in order of increasing atomic number.
The vertical columns (groups) of the periodic table are arranged so that all its elements have the same number of valence electrons (outer ring). All elements within a certain group share similar properties.
The rows are called periods. All elements in a row have the same number of electron shells.
Answer:
Platinum Gold and silver are used to make jewellery because of the following reasons. They are highly lustrous metals which are resistant to corrosion. They are highly malleable and ductile so can be transformed into any shape or design.
Explanation:
