Mrs Roberts: Well, the modern periodic table shows us all of the elements arranged in rows, which are called periods. It has changed a lot over the years as we've learned more and more about atoms.

The periodic table of chemical elements, often called the periodic table, organizes all discovered chemical elements in rows (called periods) and columns (called groups) according to increasing atomic ...

which states that the properties of the chemical elements exhibit a periodic dependence on their atomic numbers. The table is divided into four roughly rectangular areas called blocks. The rows of the ...

The records show that Mendeleev discovered the periodic system on 17 February 1869. In fact, he was ill at the time so his colleague Nikolai Menschutkin made the announcement on his behalf – on 6 ...

The periodic table of elements (often known simply as the ... The handy visual reference guide organizes known chemical elements in rows and columns, arranged by their atomic number.