C3 1 Development Of The Periodic Table Key points of C3 1 Development Of The Periodic Table. 3.0 / 5 based on 4 ratings ? ChemistryThe Periodic TableGCSEAll boards Created by: Samantha JordanCreated on: 26-03-10 19:46 C3 1.1 - The Early Periodic Table. The periodic table of the elements, developed as an attempt to classify the elements. It arranges them in a pattern according to their properties. Early versions of the periodic table failed to take account of the fact that not all of the elements were known at that time. Mendeleev's table took account of unknown elements, and so provided the basis for the modern periodic table. 1 of 5 C3 1.2 - The Modern Periodic Table. The group that an element is in is determined by its atomic (proton) number. The number of electrons in the highest energy level of an atom, determines its chemical properties. We can explain trends as we go down a group, in terms of the number of energy levels in the atoms. 2 of 5 C3 1.3 - Group 1 - The Alkali Metals. The elements in Group 1 of the periodic table are called the alkali metals. The metals all react with water to produce hydrogen and an alkaline solution containing the metal hydroxide. The reactivity of the alkali metals increases as we go down the group. 3 of 5 C3 1.4 - Group 7 - The Halogens. The halogens exist as diatomic molecules. The halogens all form ions with a single, negative charge. The halogens fom covalent compounds by sharing electrons with other non-metals. The reactivity of the halogens decreases going down the group. 4 of 5 C3 1.5 - The Transition Elements. Nearly all the transition elements have high melting points, and high densities. The transition metals are strong and hard, and are good conductors of electricity and heat. The transition metals do not react vigorously with oxygen or water. 5 of 5
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