Q&A for How to Read the Periodic Table

The number of protons in an atom of an element is represented by its atomic number which is located at the top of the element's box on the periodic table

Since atomic mass is the combined weight of the particles in the nucleus, it increases along with atomic number, which is the number of protons in an atom of that element. As such, lighter atomic mass is found in the upper left corner of the table and increases with atomic number moving to the right and down the table.

The atom becomes a positively charged ion. It will be positively charged because the number of protons is now greater than the number of electrons. Protons are positively charged, while electrons are negatively charged. Usually an atom has the same number of electrons as protons, but when there are more protons, the atom has an overall positive charge.

The atomic mass, given in atomic mass units (amu), is generally very close to the atom's mass number. The mass number is found by adding the number of protons and neutrons in the atom. This number is based on Carbon-12, and as a result, Carbon-12 has an atomic mass of 12. However, other elements have decimal atomic masses, such as Hydrogen, which has a mass number of 1 but an atomic mass of 1.0079 amu. Essentially, it is the total mass of the atom, electrons included. Closely related is the relative atomic mass or the atomic weight. This takes into account the relative abundance of an element's isotope on Earth. The atomic weight is a weighted average of the element's isotopes.

There are an equal number of protons and electrons in each element. The atomic number tells you how many protons exist, so if an element has two protons it will have two electrons.

A molecule is made up of multiple elements, so there aren't any molecules in an element. You may have meant to ask about moles, in which case, you would look up or calculate the molar mass of the particular element you're looking at. If you want to learn more about calculating molar mass, check out this wikiHow article .

Yes. You subtract the number of protons from the mass number. Mass number - number of protons = number of neutrons.

You could try to as a hobby, but there really is no point as you won't use it at all after you graduate unless you're undertaking a career that has to do with science. I suggest memorizing the most iconic and common atom elements such as Carbon and Oxygen, as these are the types that will most likely appear in exams.

An electron is a negative subatomic particle, which is a particle that makes up an atom. Electrons of each atom float around outside the nucleus. Neutrons, on the other hand, are subatomic particles with no charge, and they make up part of the nucleus of an atom.

The atomic weight is the decimal point. It should go in order from lightest to heaviest.

Those specific elements were newly discovered elements without an official name. For example, element 118 was named ununoctium (Uuo) because of the atomic number. Later, it was officially named oganesson (Og). They all were officially given names back in 2018, so the periodic table currently doesn't have any elements with 3 letters in their atomic symbol.

There is no negative proton. Electrons are negative, and when you add that to a proton, it becomes a neutron with no charge.

The groups are the columns going down on the Periodic Table. The periods are the groups going across the Periodic Table.

It depends on whether the element is currently an atom, or an ion. Atoms have no charge, therefore it’ll have an equal number of protons and electrons. (Protons have positive charge, electrons are negative). You can just look at the element’s atomic number and get the number of electrons. For ions, look at its charge. A positive charge means that there are more protons than electrons, while a negative charge is vice versa. Just look at the atomic number of the element and either add or subtract from the atomic number, based on the charge, to find the number of electrons. (For example: Fe3+. There are 3 more protons than electrons, so subtract 3 from the atomic number to get the number of electrons.)

It’s easy to figure out just by looking at a Periodic Table. First check which column/Group the element is in. This will tell you how many electrons are in its outermost shell. (For example: Chlorine is in Group 7 (Group 17 for American classrooms), therefore it has 7 electrons in its outer shell.) Next, check which row/Period the element is in. This tells you how many valence shells the atom has. (For example: Chlorine is in Period 3, therefore it has 3 valence shells.) Note that different shells have different numbers of electrons: Shell 1 is always 2 electrons. Shells 2 and 3 are always 8. It gets a little more complicated from the 4th shell onwards, but the above method always works.

The periodic table shows that sodium (Na) has an atomic number of 11. The atomic number always equals the number of protons in an atom, which also equals the number of electrons in the atom (when it has no charge). So a normal sodium atom has 11 electrons.

b The number of electrons is normally equal to the atomic number.