Main-group element Main-group element In chemistry and atomic physics, the main group is the group of elements whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements. The main group includes the elements (except hydrogen, which is sometimes not included) in groups 1 and 2 (s-block), and groups 13 to 18 (p-block). The s-block elements are primarily characterised by one main oxidation state, and the p-block elements, when they have multiple oxidation states, often have common oxidation states separated by two units. Main-group elements (with some of the
Solid ground floor mm to 225 mm. Though due to poor workmanship and dust this type of floor finish fails through lifting. Terrazo: Terrazo consists of a coloured element binder or matrix and marble chips mixed to specified proportions. The finish is hardwearing, attractive and resistant to chemical attack. Ebonite strips divide the terrazo into bays to avoid shrinkage and expansion. Solid ground floor A solid ground floor consists of a layer of concrete, which in the case of a domestic building will be the surface layer brought up to ground floor level with hardcore filling under it. The advantage of a solid