what is the difference between elements in a group and elements in a period on the periodic table
Elements in the same group have similar chemical properties.
Element in the same period have properties that change periodically across the table. Check out if the elements of the same period have the same number of shells?? (Elements of the same period have electrons entering the shell that has the period number or a lower shell; for example, elements in period 3 (Na through Ar) have electrons entering shell n = 3 while elements in period 4 (K through Kr) have electrons entering shell n = 4 for K, Ca,Ga, As, Se, Br, and Kr or n = 3 for Sc through Zn.)
The main difference between elements in a group and elements in a period on the periodic table is their arrangement and properties.
Elements in the same group or column have similar chemical properties because they have the same number of valence electrons. Valence electrons are the electrons in the outermost shell of an atom and they are responsible for the chemical behavior of an element. For example, all elements in Group 1 (such as hydrogen, lithium, sodium, and potassium) have one valence electron, which makes them highly reactive and prone to losing that one electron to form a positive ion.
On the other hand, elements in the same period or row have properties that change periodically across the table. Each period corresponds to the number of electron shells occupied by the elements in that row. As you move from left to right across a period, the number of valence electrons increases by one with each element. For example, in Period 3, sodium has one valence electron, while chlorine (at the other end of the period) has seven valence electrons. This increase in valence electrons across a period leads to predictable trends in properties such as atomic radius, ionization energy, and electronegativity.
To determine if elements of the same period have the same number of shells, you can simply look at their position on the periodic table. Each period represents a new energy level or shell being filled with electrons. The period number corresponds to the number of the highest energy level (or shell) in which electrons are located in the elements of that period.
So, in summary, elements in the same group have similar properties because they have the same number of valence electrons, while elements in the same period have properties that change as the number of shells or energy levels occupied increase across the table.