Elements And Their Properties, Periodic Table And Trends, Compounds Unit 5 - Quiz 1

Explanation
Based on the given physical properties, the substance is most likely a metal. Metals are known for their high electrical conductivity, malleability, and high luster. These properties are characteristic of metals, whereas nonmetals typically have low electrical conductivity and are not malleable. Without more data, it is reasonable to conclude that the substance is a metal.

Explanation
Mendeleev is credited with developing the periodic table. He arranged the elements based on their atomic mass and observed patterns in their properties. His table allowed for the prediction of the existence and properties of undiscovered elements. Mendeleev's work laid the foundation for the modern periodic table that we use today. Dalton, Bohr, and Rutherford made significant contributions to the field of chemistry and atomic theory, but they did not develop the periodic table.

Explanation
A period is not a horizontal row on the periodic table. It is a vertical column. The correct answer is False.

Explanation
The element O (oxygen) is not in the same family as the other elements listed (N, P, and Sb) on the periodic table. Oxygen belongs to the chalcogens family, while nitrogen, phosphorus, and antimony belong to the pnictogens family.

Explanation
Silicon would be classified as a metalloid because it exhibits properties of both metals and nonmetals. It is a semiconductor, meaning it can conduct electricity under certain conditions but not as well as a metal. Silicon is also brittle and has a high melting point, similar to nonmetals. Therefore, it falls into the category of metalloids, which have characteristics that are intermediate between metals and nonmetals.

Explanation
Noble gases are the elements in the periodic table that have a full outer electron shell, making them highly stable and unreactive. Due to their stable electron configuration, noble gases do not readily form compounds with other elements. This is because they already have a complete set of valence electrons and do not need to gain, lose, or share electrons with other elements to achieve stability. Therefore, noble gases are the only family listed that contains elements that will not form compounds.

Explanation
The atomic weight of an element is the average mass of its atoms, taking into account the different isotopes and their abundance. The atomic weight of hydrogen is indeed 1.00794, as stated in the question. This value is calculated based on the natural abundance of hydrogen isotopes, with the most common isotope being hydrogen-1. Therefore, the given answer "True" is correct.

Explanation
Cobalt is an element with atomic number 27, which represents the number of protons in the nucleus of an atom. Therefore, the correct answer is 27.

Explanation
The atomic mass of an element is the average mass of all the isotopes of that element, taking into account their relative abundance. The atomic mass of cobalt is 59, which means that on average, cobalt atoms have a mass of 59 atomic mass units (amu).

Explanation
The far left side of the periodic table is where the most metallic elements are located. These elements tend to have properties such as high electrical and thermal conductivity, luster, and malleability. As you move from left to right across the periodic table, the metallic properties decrease and the non-metallic properties increase. Therefore, if an unknown element displays many extremely strong metallic properties, it is most likely to be located on the far left side of the periodic table.

Explanation
The question asks for the three known forms of hydrogen and their characteristics. The correct answer is "isotopes, protons, neutrons." Isotopes refer to different forms of an element that have the same number of protons (which determines the element) but different numbers of neutrons. In the case of hydrogen, there are three isotopes: protium (1 proton, 0 neutrons), deuterium (1 proton, 1 neutron), and tritium (1 proton, 2 neutrons). Therefore, the answer accurately describes the relationship between isotopes, protons, and neutrons in hydrogen.