Periodic Table And Electron Configuration

Helium (He) is the noble gas with the lowest atomic mass. It has an atomic number of 2, meaning it has 2 protons in its nucleus. Helium is the second lightest element in the periodic table, after hydrogen, and is known for its low density and lack of reactivity. It is a colorless, odorless, and tasteless gas that is commonly used in balloons and as a cooling agent in various industrial processes.

Fr is the symbol for francium, which is the alkali metal with the highest atomic mass. Francium has an atomic number of 87 and an atomic mass of approximately 223 atomic mass units. It is a highly reactive and radioactive element that is extremely rare in nature. Due to its high reactivity and short half-life, francium is difficult to study and is mainly used for scientific research purposes.

The modern periodic table is correctly described as having 18 groups and 7 periods. The groups represent the vertical columns of elements with similar properties, while the periods represent the horizontal rows that indicate the number of electron shells in an atom. The modern periodic table is organized based on the increasing atomic number of elements, allowing for a better understanding of their properties and trends.

Group 14 in the periodic table contains a metalloid. Metalloids are elements that have properties of both metals and nonmetals. In Group 14, the element carbon is a nonmetal, while the elements silicon and germanium are metalloids. Therefore, Group 14 is the correct answer as it contains a metalloid.

Boron (B) is the only metalloid in Group 13 of the periodic table. Metalloids are elements that have properties of both metals and nonmetals. In Group 13, all the other elements (aluminum, gallium, indium, and thallium) are metals. Therefore, the symbol B is the correct answer as it represents the element boron, which is the only metalloid in Group 13.

Chlorine will closely resemble bromine (Br) in chemical properties. Both chlorine and bromine are halogens and belong to the same group in the periodic table. They have similar electronic configurations and therefore exhibit similar chemical behaviors. Both elements are highly reactive and tend to form compounds by gaining one electron to achieve a stable electron configuration.

Hg is the symbol for the element mercury, which is the only liquid transition metal at room temperature.

The correct grouping of elements should follow a pattern or trend in terms of their properties or characteristics. In this case, the grouping of potassium, silicon, strontium, and argon is not correct because these elements do not have similar properties or characteristics. Potassium is an alkali metal, silicon is a metalloid, strontium is an alkaline earth metal, and argon is a noble gas. Therefore, this grouping does not follow any logical pattern or trend.

Copper does not belong to the group of representative elements because it is a transition metal, while the other elements listed (calcium, xenon, and hydrogen) are representative elements. Representative elements are found in the s and p blocks of the periodic table and exhibit a wide range of chemical properties. Transition metals, on the other hand, are found in the d block and have different properties and characteristics compared to representative elements.

The symbol "La" represents the element Lanthanum, which is an inner transition metal. It has the lowest atomic number among all the inner transition metals.