Chemical Interactions - Chapter 1

Hydrogen is the most common element in the universe because it is the lightest and simplest element, making up about 75% of its elemental mass. It is found in vast quantities in stars and interstellar clouds, and is a key component in the formation of stars and galaxies. Additionally, hydrogen is a major component of water and organic compounds, which are essential for life as we know it. Therefore, hydrogen is the most abundant element in the universe.

The periodic table is organized based on the atomic number of elements, which represents the number of protons in the nucleus of an atom. As scientists discover new elements, they are added to the periodic table based on their atomic number. Since the given answer suggests that the new element will fit at the end of the periodic table after element 118, it implies that the new element will have a higher atomic number than all the currently known elements. This aligns with the principle of how the periodic table is structured, with elements arranged in order of increasing atomic number.

In this diagram, one column is referred to as a "group". The term "group" typically represents a collection of individuals who come together for a common purpose or share a common characteristic. In the context of the diagram, it suggests that the column represents a collection of related or similar elements.

The atomic mass number of an atom is determined by the total number of protons and neutrons in its nucleus. This number represents the combined mass of the protons and neutrons in the atom. The atomic mass number is important in identifying and categorizing different elements because it helps determine the overall mass and stability of the atom. The atomic symbol represents the specific element, while the atomic number represents the number of protons in the nucleus. Size, on the other hand, is not directly determined by the number of protons and neutrons in the nucleus.

The given element has a dull surface and does not conduct electricity well, which are characteristic properties of nonmetals. Nonmetals are elements that are poor conductors of heat and electricity, and they generally have dull or brittle surfaces. Therefore, the correct answer is nonmetal.

A metalloid is an element that exhibits properties of both metals and nonmetals. It falls in between metals and nonmetals on the periodic table. Metalloids have characteristics of metals such as being good conductors of electricity, but also exhibit nonmetallic properties such as being brittle and having low melting points. They are often used in semiconductors and have properties that make them useful in electronic devices. Therefore, the correct answer is metalloid.

A row of the periodic table is called a period. The periodic table is organized into rows and columns, with each row representing a different period. Within each period, the elements have the same number of electron shells. Therefore, the correct answer is "a period."

A metal is a substance that has a shiny surface and can be easily shaped by drawing it into a long thin wire. This property is known as malleability. Metals generally have high electrical and thermal conductivity, and are often solid at room temperature. Examples of metals include iron, copper, and aluminum.

Gold is classified as a transition metal because it is located in the middle of the periodic table. Transition metals are found in the d-block of the periodic table and have properties such as high melting and boiling points, good conductivity, and the ability to form colored compounds. Gold exhibits these characteristics, making it a transition metal.

When a calcium atom loses two electrons, it becomes a positive ion. This is because calcium has 20 electrons in its neutral state, and by losing two electrons, it achieves a stable electron configuration similar to that of a noble gas (argon) with 18 electrons. The loss of electrons creates a net positive charge, resulting in a positive ion.

Atoms of an element always have a certain number of protons. Protons are positively charged particles found in the nucleus of an atom. The number of protons in an atom determines its atomic number and identifies the element. The other options - neutrons, electrons, and ions - may or may not be present in an atom depending on the specific element and its atomic structure.

The chemist's observation that the element does not react with any other element suggests that it has a stable electron configuration. Noble gases are known for their stable electron configurations, as they have a full outer shell of electrons. Therefore, it is most likely that the element being tested is a noble gas.

The alkali metals are located in Group 1 of the periodic table, which is on the far left side. These elements are highly reactive and have only one valence electron, making them easily lose it to form positive ions. They are known for their low melting points, softness, and ability to react vigorously with water. Therefore, the given answer "alkali metal" is correct because it accurately describes the group that is at the far left of the periodic table.

The correct answer is the protons and neutrons are in the nucleus which is surrounded by a cloud of electrons. This answer accurately describes the structure of an atom. Protons and neutrons are located in the nucleus, which is the central part of the atom. The nucleus is surrounded by a cloud of electrons, which occupy energy levels or orbitals around the nucleus. This arrangement is known as the electron cloud model and is widely accepted in modern atomic theory.

Halogen is the correct answer because halogens are a group of elements that are often used to kill bacteria. They get their name from the Greek words for "salt formers" because they readily form salts when they react with metals. Halogens include elements such as chlorine, fluorine, bromine, and iodine, which are commonly used as disinfectants and antiseptics due to their ability to kill bacteria and other microorganisms.

When a neutral magnesium atom loses two electrons, it becomes a magnesium ion with a 2+ charge. This is because electrons have a negative charge, and when they are removed from the atom, the overall charge of the atom becomes positive. Losing electrons increases the positive charge, resulting in a 2+ charge for the magnesium ion.

Isotopes of an element differ in the number of neutrons they have. Isotopes are atoms of the same element that have the same number of protons (atomic number) and electrons, but they can have different numbers of neutrons. The number of neutrons in an isotope affects its atomic mass and stability. Therefore, the correct answer is "number of neutrons."