Atomic Structure and Ionic Bonding

Magnesium (Mg) is an alkaline earth metal found in Group 2 of the periodic table. It has two valence electrons in its outer shell. To achieve a stable electron configuration, magnesium tends to lose these two electrons, resulting in a +2 charge. This means that when it forms an ion, it carries a positive charge of +2, indicating it has lost two negatively charged electrons.

Calcium has a charge of +2 (Ca²⁺) and chlorine has a charge of -1 (Cl⁻). To balance the charges in the ionic compound, two chloride ions are needed to neutralize one calcium ion. This results in the formula CaCl₂, indicating that for every one calcium ion, there are two chloride ions. Thus, the correct formula for the ionic compound formed between calcium and chlorine is CaCl₂.

Ionic compounds are formed through the transfer of electrons from metal atoms to non-metal atoms. Metals, which have few electrons in their outer shell, readily lose electrons, becoming positively charged ions (cations). Non-metals, on the other hand, have a higher electronegativity and tend to gain these electrons, becoming negatively charged ions (anions). The resulting oppositely charged ions experience a strong electrostatic attraction, leading to the formation of ionic bonds and ultimately creating an ionic compound. This process is fundamental to the structure and properties of ionic substances.

In the formation of sodium chloride (NaCl), sodium (Na) undergoes an electron transfer process where it loses one electron. This loss of an electron allows sodium to achieve a stable electron configuration similar to that of noble gases. By losing an electron, sodium becomes positively charged, forming the ion Na⁺. This process is crucial for the ionic bond formation with chlorine, which gains that electron to become Cl⁻, resulting in the stable compound NaCl.

An oxide ion (O) carries a charge of −2 because it gains two electrons to achieve a stable electron configuration, similar to that of the nearest noble gas, neon. This gain of electrons results in a net negative charge, as the number of electrons exceeds the number of protons in the ion. Thus, the oxide ion is commonly represented as O²⁻, indicating its charge of −2.

Atoms are composed of three main sub-atomic particles: protons, neutrons, and electrons. Protons are positively charged particles found in the nucleus, neutrons are neutral particles that also reside in the nucleus, and electrons are negatively charged particles that orbit the nucleus. This combination of particles determines the atom's identity and its chemical properties, with protons defining the element, neutrons influencing stability, and electrons playing a key role in chemical bonding and reactions.

Cl⁻ is the anion formed when a chlorine atom gains an electron. This negatively charged ion is referred to as chloride. In contrast, chlorate refers to a different ion (ClO₃⁻) that contains oxygen, while chlorine ion typically refers to the neutral chlorine atom or its cation form. Chlorous is related to chlorous acid (HClO₂) and its derivatives. Thus, the name "chloride" specifically identifies the ion resulting from chlorine's electron gain, distinguishing it clearly from other chlorine-related species.

Sulfur, being in Group 6 of the periodic table, has six valence electrons and needs two more to achieve a stable octet configuration. As a result, sulfur tends to gain two electrons, forming an anion with a charge of -2 (S²⁻). In contrast, magnesium and calcium from Group 2, and potassium from Group 1, typically lose electrons to form cations rather than gaining them to form anions. Thus, sulfur is the element among the options that will form an anion.

Sodium, located in Group 1 of the periodic table, has one electron in its outermost shell. To achieve a stable electron configuration, it tends to lose this electron easily, resulting in the formation of a cation with a positive charge (Na⁺). In contrast, chlorine, oxygen, and nitrogen typically gain electrons to form anions, as they require more electrons to fill their outer shells and achieve stability. Thus, sodium is the element that predominantly forms a cation.

An element's period number in the periodic table indicates the number of occupied electron shells surrounding its nucleus. Each period corresponds to a new electron shell being filled with electrons. For example, elements in the first period have one occupied shell, while those in the second period have two. This organization helps understand the element's electron configuration and its chemical properties, as the number of occupied shells influences how the element interacts with others.

An element's group number in the periodic table indicates the number of valence electrons, which are the electrons in the outermost shell. Elements in the same group share similar chemical properties due to having the same number of valence electrons, influencing their reactivity and bonding behavior. For example, group 1 elements have one valence electron, while group 17 elements have seven. This relationship helps predict how elements will interact with one another in chemical reactions.

In the periodic table, groups refer to the vertical columns that categorize elements with similar chemical properties and valence electron configurations. Each group contains elements that share common characteristics, such as reactivity and bonding behavior. This vertical arrangement allows for easy comparison of these elements, highlighting trends in their properties as you move down the column. In contrast, horizontal rows, known as periods, represent elements with increasing atomic numbers and varying properties.

An element's atomic number indicates the number of protons and, in a neutral atom, the number of electrons. With an atomic number of 11, this element has 11 protons and 11 electrons. The mass number is the sum of protons and neutrons; in this case, 23 (mass number) - 11 (protons) equals 12 neutrons. Therefore, the element has 11 electrons, 11 protons, and 12 neutrons.

To determine the number of neutrons in an atom, subtract the atomic number from the mass number. The atomic number (18) represents the number of protons, while the mass number (40) is the total number of protons and neutrons. Thus, the calculation is: 40 (mass number) - 18 (atomic number) = 22 neutrons. Therefore, this atom has 22 neutrons.

The atomic number of an element uniquely identifies it and is defined as the number of protons present in its nucleus. Protons carry a positive charge and determine the element's identity and position on the periodic table. While neutrons contribute to the atomic mass and electrons influence chemical behavior, it is the number of protons that defines the element itself, making the atomic number a fundamental characteristic in chemistry.

The mass number of an atom represents the combined total of protons and neutrons found in its nucleus. Protons contribute positively to the mass, while neutrons add to the mass without an electrical charge. Electrons, being much lighter and located outside the nucleus, do not factor into the mass number. Therefore, to determine an atom's mass number, one must sum the quantities of protons and neutrons, providing a clear measure of the atom's overall mass.

An element with atomic number 15 has 15 electrons. The electronic configuration is determined by filling the energy levels according to the Aufbau principle. The first energy level can hold 2 electrons, the second can hold 8, and the third can hold up to 18 but will only need to hold 5 in this case. Therefore, the correct distribution of electrons is 2 in the first shell, 8 in the second shell, and 5 in the third shell, resulting in the configuration 2, 8, 5.

Electrons are sub-atomic particles that possess a very small mass, approximately 1/1836 that of a proton. In contrast, protons and neutrons have significantly greater masses, making electrons negligible in comparison. This distinction is crucial in atomic structure, where the mass of the nucleus (comprised of protons and neutrons) is much greater than that of the surrounding electrons, which primarily contribute to the atom's volume and chemical properties rather than its mass.

Protons and neutrons are located in the nucleus, which is the dense central core of an atom. This nucleus contains most of the atom's mass, with protons carrying a positive charge and neutrons being neutral. The arrangement of protons and neutrons in the nucleus is fundamental to the atom's identity and stability, while electrons orbit the nucleus in defined energy levels or shells. This structure is crucial for understanding atomic behavior and interactions in chemistry and physics.

Protons, neutrons, and electrons are subatomic particles with distinct electric charges. Protons carry a positive charge of +1, which contributes to the overall positive charge of atomic nuclei. Neutrons are electrically neutral, having a charge of 0, and they help stabilize the nucleus. Electrons, found in the electron cloud surrounding the nucleus, have a negative charge of −1. This arrangement of charges is fundamental to the structure of atoms and influences chemical behavior and bonding.