The Periodic Table - IGCSE Chemistry - Dr Hanaa Assil

Dr. Hanah introduces the periodic table, emphasizing it is provided in exams and arranged by atomic number. She explains the key of symbols, atomic mass, and proton number, cautioning that layouts may differ in other tables. She gives examples with lithium, clarifying atomic number as the smaller figure, representing protons, while mass number is protons plus neutrons. She teaches the organization of metals and non-metals across the table, identifying vertical groups and horizontal periods, noting how group numbers indicate electrons in the outer shell, using sodium and magnesium as examples.

Dr. Hanah further discusses the correlation between the periodic table's group number and valence electrons, using chlorine and various period elements to illustrate energy levels. A question is tackled on electronic structure alignment with group characteristics. She stresses that all elements in the same group have similar properties due to the same number of valence electrons. Group behaviors like group one's reactivity and electron distribution are elaborated. She defines metals, non-metals, alkali metals, transition metals, halogens, and noble gases based on their table position and general properties.

The section focuses on identifying metals and non-metals, especially those within the same period, and explaining metal reactivity—highlighting potassium and its comparison to lithium in terms of reactivity and melting point. It underscores the periodic table’s insights into physical properties, noting transitions and why elements like sodium need storage under oil due to reactivity. A practical question illustrates identifying metal states, and a correct statement is deduced about potassium having a soft metal quality and reactivity with water.

Discussion shifts to transition metals, underlining their physical attributes such as density, hardness, and high melting points, contrasted with group one metals’ softness and low density. Chemical properties like catalytic function and colored compound formation of transition metals are explained. The lesson includes comparing sodium chloride's appearance in different states, emphasizing group variations in valence electrons. The properties and physical attributes differentiate transition metals from other groups, especially visible through comparisons involving density, hardness, and compound colorization.

Group seven (halogens) are detailed, noting their reactivity and physical states (gas to solid) across the group. The reactivity order within the group and effects of state transitions and color changes from gases to solids are addressed. Reaction dynamics explained through displacement reactions illustrate the reactivity order, with practical examples involving bromine and chlorine interactions. One learns the rationale of halogens’ displacement tendencies with solution reactions marking reactivity trends as teaching tools.

Continuing with halogens, the subject is bromine’s interactions notably with potassium chloride and iodide, outlining how these scenarios demonstrate halogen reactivity order, leading to chlorine being the most reactive. Next, group zero (noble gases) are introduced as unreactive due to having full outer electron shells. Helium is specifically mentioned for balloon filling due to this inertness, compared to hydrogen’s explosiveness. Uses for argon in bulbs and neon in lights reflect practical applications stemming from noble gases’ properties.

Emphasis on noble gases covers their monatomic state, non-reactivity, full outer shells, and practical uses, clarifying helium versus argon usage due to helium's inert nature. Periodic table positioning of gases assists in distinguishing diatomic from monatomic elements. Considerations in choosing filament materials highlight tungsten’s use due to high melting points linked with transition metal properties; argon’s role is defended against air due to its non-reactivity.