In other words, the number you’re seeing is the element’s average mass, but you might find it at a different mass depending on the number of neutrons it contains. The atomic mass number on the modern periodic table is the weighted average of the atomic masses of that element’s naturally occurring isotopes. Therefore, different isotopes will have different amounts of mass. Just as an ion is an element with more or fewer electrons than usual, an isotope is a version of an element that contains a different number of neutrons. That’s because they sometimes contain different numbers of neutrons. However, even two atoms of the same element might have different weights. If you read the periodic table, you’ll see that oxygen weighs 15.999 u. This number tells you how much a single atom of that element weighs in atomic mass units. The atomic mass is the number usually - but not always - located at the bottom of an element key. That just tells you the number of protons. Therefore, don’t assume how many electrons an element has based on its atomic number on the periodic table. Cations are positively charged, while anions have a negative charge. These positively and negatively charged atoms are called ions. Others have fewer electrons than protons, giving them a positive charge. Some atoms have more electrons than protons, giving them a negative charge. However, this is only sometimes the case. It’s worth noting that most atoms have an equal number of protons and electrons, so the atomic number gives you a hint as to how many electrons an atom contains. Each element has one more proton than the one before it. Not only does it let you count the protons, but it also determines the element’s place on the table.

The number of protons in an element cannot change or else it would become a different element entirely!Įvery element on the periodic table has an atomic number assigned to it. Since oxygen is number 8 on the periodic table, that tells you there are eight positive protons in the center of each atom. The element key helps you learn about the individual elements in the periodic table.Īn element’s atomic number lets you know how many protons are in the nucleus. What do each of these sections on the element key tell us?Ĭomponents of an element key. Oxygen, for example, has an atomic number of 8, an atomic weight of 15.996 and a unique symbol, O. Each key contains an element’s name, unique symbol, atomic weight and atomic number. The box containing each element’s information is known as the element key. Once you’re familiar with the element key, layout and structure, it’s easy to read the periodic table. Scientists are trying to create new elements by using particle accelerometers, but this can be a tricky process. As of 2023, the periodic table contains 118 unique elements. For example, water is a combination of hydrogen and oxygen atoms. The periodic table of elements contains the building blocks that make up all the objects in the world. When you buy through links on our site, we may earn an affiliate commision.

Periodic table groups color coded