Chemistry Ch. 13 S And P Block Elements

Silicon is a semiconductor because it has properties of both conductors and insulators. It can conduct electricity under certain conditions, but not as well as a good conductor like copper or silver. At the same time, it can also act as an insulator and resist the flow of electricity. This makes silicon a crucial material in the field of electronics, as it can be used to control the flow of current in devices such as transistors and diodes.

Electronegativity is a measure of an atom's tendency to attract a bonding pair of electrons. It indicates the ability of an atom to attract and hold onto electrons in a chemical bond. It is an important concept in understanding the polarity of chemical bonds and the distribution of electrons in molecules.

The correct answer is "nuclear charge increase". As we move from left to right in a period, the number of protons in the nucleus increases. This leads to a greater positive charge in the nucleus, which attracts the electrons more strongly and pulls them closer to the nucleus. As a result, the atomic radius decreases. The other options mentioned - number of electrons increase, number of neutrons increase, and atomic number increase - do not directly affect the atomic radius in the same way as the increase in nuclear charge.

The statement "they form carbonates which decompose on heating" is incorrect. Alkali metals do form carbonates, but these carbonates are stable and do not decompose on heating.

Aluminium hydroxide is considered amphoteric because it can act as both an acid and a base. It can react with acids to form salts and water, and it can also react with bases to form complex ions. This dual nature allows aluminium hydroxide to exhibit both acidic and alkaline properties, making it amphoteric.

Metallic oxides are generally basic in nature. This is because they react with water to form metal hydroxides, which are alkaline in nature. These oxides have a tendency to donate hydroxide ions (OH-) when dissolved in water, resulting in a basic solution. Examples of basic metallic oxides include sodium oxide (Na2O) and calcium oxide (CaO).

The elements in Group I-A give colors in flame due to their single electron in the outermost orbit. When these elements are heated, the outermost electron absorbs energy and jumps to a higher energy level. As the electron returns to its original energy level, it releases the absorbed energy in the form of visible light, which gives rise to the characteristic colors observed in flames.

Aluminium chloride is pale yellow in color.

Cs (Cesium) is the most reactive alkali metal because it has the largest atomic radius and the lowest ionization energy among the options given. The larger the atomic radius, the easier it is for the outermost electron to be removed, resulting in a lower ionization energy. Cs has the largest atomic radius, making it easier for its outermost electron to be removed, thus making it the most reactive alkali metal.

The correct answer is NaOCl. Sodium hypochlorite is a chemical compound made up of sodium, oxygen, and chlorine. The formula NaOCl represents the correct combination of these elements. NaCl, NaClO4, and NaClO3 do not accurately represent the composition of sodium hypochlorite.

Silicon dioxide is a giant covalent oxide because it consists of a three-dimensional network of covalent bonds between silicon and oxygen atoms. Each silicon atom is bonded to four oxygen atoms, and each oxygen atom is bonded to two silicon atoms. This results in a strong and stable structure, making silicon dioxide a solid with a high melting and boiling point. In contrast, phosphorus (V) oxide, carbon dioxide, and sulfur trioxide do not form giant covalent structures and have different bonding arrangements.

Sulfur burns with a blue flame because when sulfur reacts with oxygen, it undergoes combustion and produces sulfur dioxide gas. The blue flame is an indication of a complete combustion process, where there is sufficient oxygen available for the reaction. The blue color is a result of the excitation of electrons in the sulfur molecules, which emit light in the blue region of the electromagnetic spectrum.

Fluorine is known to be the most electronegative element with an electronegativity value of 4. Since Cs is stated to be the least electronegative element, it can be inferred that its electronegativity value would be lower than that of fluorine. Among the given options, the closest value to being lower than 4 is 0.7. Therefore, the electronegativity value of Cs is 0.7.

Phosphorus burns with a white flame because when it is heated, the energy causes the electrons in the phosphorus atoms to become excited. As the electrons return to their ground state, they release energy in the form of light. The specific wavelengths of light emitted by phosphorus correspond to the color white, resulting in a white flame.

The correct answer is S3O9. This is because the trimeric formula for sulfur tri-oxide is represented by S3O9, which indicates that there are three sulfur atoms and nine oxygen atoms in the compound. The other options, SO3, S2O6, and S2O2, do not accurately represent the trimeric formula for sulfur tri-oxide.