The smallest atom in the periodic table in terms of mass is hydrogen, which has only one proton and one electron. Hydrogen has no neutrons. The element has an atomic number of 1 and atomic weight of 1.00794, making it the smallest of all the elements.
Henry Cavendish first recognized hydrogen as its own element in 1766. It takes its name from the Greek words "hydros" and "genes," which mean "water forming."
Hydrogen is the most abundant element in the universe. It is the main component of the atmospheres of several planets. The sun relies on hydrogen as a source of its energy production. On Earth, hydrogen forms many important compounds, including water (h2O,) hydrochloric acid (HCl) and ammonia (NH3.)Learn More
Three elements on the periodic table are magnetic: iron, nickel and cobalt. There are also a number of metals that take on slight magnetic properties when subjected to a magnetic field.Full Answer >
On the periodic table, the seven horizontal rows are called periods. On the left-hand side of the periodic table, the row numbers are given as one through seven. Moving across a period from left to right, the atomic number of the elements increases.Full Answer >
The MCAT periodic table is the periodic table made available to test takers of the Medical College Admission Test (MCAT). It includes the same information as typical periodic tables, listing the atomic numbers and atomic weights of each element.Full Answer >
Mendeleev arranged the periodic table in order of increasing atomic weight of the elements. He determined that there was a pattern when he arranged these elements into horizontal rows.Full Answer >