In chemistry, the periodic table is a tabular representation of chemical elements. It arranges the elements in order of atomic number and shows their chemical properties. There are 118 elements in the table, and each one has its own unique set of characteristics. The order of the elements is based on their electron configuration, which determines how they react with other atoms.
What are Periods?
- In the periodic table, periods are horizontal rows. The elements in a period have similarities in their electron configurations. The first element in a period must have one shell of electrons, and each element after that must have an additional shell until the outermost orbital is full. For example, the first element in period 3 is lithium. It has one shell of electrons.
- The second element is beryllium, and it has two shells of electrons. This sequence continues until we reach argon, which has three shells of electrons and is the last element in period 3. All of the elements in a period have similar chemical properties because they have the same number of valence electrons.
- Valence electrons are those in the outermost orbital and are responsible for chemical reactivity. In general, elements with more valence electrons are more reactive than those with fewer valence electrons. That’s because it takes more energy to remove an electron from an atom that already has a full outer orbital than it does to remove an electron from an atom that doesn’t have a full outer orbital.
What are Groups?
- The term ‘group’ in the periodic table refers to the columns of elements. There are 18 groups in the periodic table, and each element in a group has the same number of valence electrons. The elements in each group have similar chemical properties, which is why they are often referred to as ‘families’ of elements.
- The groups are numbered from 1 to 18, and the elements within each group are listed in order of increasing atomic number. The first two groups, which are the most reactive, are called the alkali metals and the alkaline earth metals. The elements in these groups tend to be highly reactive, and they are often found in nature in their elemental form (such as sodium and magnesium).
- The next six groups (3-8) are called transition metals. These elements have intermediate reactivity, and they often form compounds with other elements (such as iron oxide). The final eight groups (9-18) are called post-transition metals, inner transition metals, or rare earth metals. These elements are generally less reactive than transition metals, and they often occur in nature in mineral form (such as copper sulfate).
Difference between Periods and Groups
The elements in the periodic table are arranged in order of increasing atomic number. The elements with similar chemical properties are in the same group. The columns of the periodic table are called groups and the rows are called periods. The elements in a group have the same number of valence electrons in their outermost energy level.
Because they have the same number of valence electrons, they also have similar chemical properties. The elements in a period have different numbers of valence electrons. The first element in a period has one valence electron, and each subsequent element has one more valence electron than the previous element. As a result, the elements in a period have different chemical properties.
Periods in the periodic table are regions where elements share common properties. In each period, electrons fill orbitals in shells in a specific order. The first shell can hold two electrons, the second can hold eight, and so on. When all of the slots in the outermost shell are filled, an element is stable and does not want to give up or gain any more electrons. This makes it harder for atoms of that element to form bonds with other atoms-they become “reactive”.
Groups in the periodic table are vertical columns of elements that have similar chemical properties because they have the same number of valence electrons (electrons in the outermost shell). Elements within a group often react similarly to one.