periodic table definition period chemistry definition

It depends on the oxidation state of a chemical molecule. Sodium metal is the most electropositive element in the third period therefore forms the most basic oxide while aluminium and silicon forms amphoteric oxides and sulphur and chlorine atoms form acidic oxide.Īmphoteric oxides: It is an oxide that can show the properties of both acidic as well as basic oxides. For example: Consider elements from the third period of the modern periodic table. (ii) As we move from left to right in a period, the acidic nature of oxides increases whereas the basic nature of oxides decreases. Thus, it concludes that reactivity of non-metals increases on moving left to right in a period. Therefore, the chlorine atom is the most reactive nonmetal in the third period. For example: In the third period, phosphorus, sulphur and chlorine are non-metals and do not have a tendency to lose electrons but they can accept electrons.īecause, chlorine needs one electron to reach noble gas configuration whereas phosphorus and sulphur needs three and two electrons respectively. Hence it concludes that reactivity of metals decreases on moving left to right in a period.įor non-metals, the chemical reactivity increases when you move left to right in a period. Therefore, the sodium metal is the most reactive metal in a third period. All the three metals are electropositive in nature and are in need of donated electrons to gain stability.īecause, sodium metals require to donate a single electron while magnesium and aluminium donates two and three electrons respectively. For example, sodium, magnesium and aluminium metals are present in the third group. (b) (i) For metals, the chemical reactivity decreases when you move left to right in a period. Therefore, the atomic size of the elements decreases in a period. As in a period, elements have the same electron shells, so an increase in the number of electrons causes an increase in the effective nuclear charge. On moving left to right in a period, atomic number increases that indicates the increase in number of electrons and protons in an atom.

In a period, each next element exceeds by one proton and therefore has less metallic character than its precursor. All elements present in a period will have the same number of electron shells. (a) Period: In the modern periodic table, the horizontal rows are called periods. The horizontal rows are termed as periods and vertical columns are termed as groups. In the modern periodic table, the elements are arranged in a well-defined manner. Assess students understanding of prior learning by revisiting the topic of atomic structure. Quiz your students on periodic table trends, such as melting points, ionisation energies and atomic radiuses. Hint: Modern periodic law is defined as the physical and the chemical trait of each element are the periodic functions of its atomic number. Help post-16 students consolidate their ideas about atoms and atomic structure by working in pairs to identify key concepts.

Periodic table definition period chemistry definition