Semester Review: Units 1-5

A nail rusting in the rain is a chemical change because it involves a chemical reaction between the iron in the nail and the oxygen in the air, resulting in the formation of iron oxide (rust). This process is irreversible and leads to a change in the chemical composition of the nail.

A substance that is firm where molecules can only vibrate in place is called a solid. In solids, the molecules are closely packed together and have a fixed shape and volume. The strong intermolecular forces between the molecules prevent them from moving freely, allowing only vibration in their positions. This characteristic of solids distinguishes them from liquids and gases, where molecules have more freedom of movement.

The outermost electron shell is where valence electrons are located. Valence electrons are the electrons in the outermost energy level of an atom and are responsible for the chemical properties of an element. These electrons participate in chemical bonding and determine how an atom interacts with other atoms. Therefore, the outermost electron shell is crucial in understanding the behavior and reactivity of elements.

The correct answer is 47. This is because the atomic number of silver (Ag) is 47, which represents the number of protons in the nucleus of an atom of silver. Protons are positively charged particles and their number determines the element's identity. In this case, silver has 47 protons.

A gas is a substance that has no definite shape or volume and its molecules are completely free. Unlike solids and liquids, the molecules in a gas are not held together tightly and can move around freely. This allows gases to fill any container they are placed in and easily expand or contract depending on the conditions. Examples of gases include oxygen, nitrogen, and carbon dioxide.

The statement in Unit 4 that "A neutron is negatively charged" is incorrect. Neutrons are actually neutral particles, which means they have no charge. Unlike protons, which are positively charged, and electrons, which are negatively charged, neutrons do not possess any charge.

An atom of magnesium (Mg) has 12 protons, 12 neutrons, and 12 electrons. The atomic number of an element is determined by the number of protons in its nucleus, so since magnesium has 12 protons, it is the element with an atomic number of 12. The atomic mass is determined by the sum of protons and neutrons, so with 12 neutrons, magnesium has an atomic mass of 24. Additionally, in a neutral atom, the number of electrons is equal to the number of protons, so magnesium also has 12 electrons.

Salts can be removed from a solution by using evaporation. Over time, all of the solvent will leave the system as it evaporates. The salts will remain.

The correct answer is Potassium (K) because the Bohr Model shown in the question has 19 electrons, which matches the electron configuration of Potassium. Potassium has an atomic number of 19 and its electron configuration is 2-8-8-1, which corresponds to the number of electrons shown in the Bohr Model. Calcium, Fluorine, and Neon have different electron configurations and do not match the number of electrons in the Bohr Model.

Water (H2O) is the most common solvent on Earth. Solutes are dissolved in solvents.
Water is the "universal solvent".

In a sulfur molecule (S8), there are 8 sulfur atoms bonded together in a ring-like structure. Each sulfur atom has a valency of 2, which means it can form 2 bonds with other atoms. In this case, each sulfur atom is bonded to another sulfur atom, resulting in a total of 4 sulfur-sulfur bonds. Since there are 2 potassium atoms present in the molecule, and each potassium atom is bonded to one sulfur atom, there are a total of 8 potassium atoms in 4S.

A substance that can change shape but has a fixed volume and its molecules are loose is called a liquid. Liquids have the ability to flow and take the shape of their container, but their volume remains constant. The loose arrangement of molecules allows them to move freely, giving liquids their characteristic properties such as viscosity and surface tension.

The correct answer is Proton, Neutron. Protons and neutrons are located in the nucleus of an atom. Protons have a positive charge, while neutrons have no charge. Electrons, on the other hand, are located outside the nucleus in energy levels or shells. They have a negative charge and orbit around the nucleus.

The correct answer is Sulfur (S) because the question asks for the element shown in the following Bohr Model, and out of the options given, Sulfur (S) is the only element mentioned.

An ion is an atom that has lost or gained electrons. When an atom loses electrons, it becomes positively charged and is called a cation. When an atom gains electrons, it becomes negatively charged and is called an anion. Therefore, an ion is the correct answer for an atom that has lost or gained electrons.

The term that describes the process of testing a hypothesis is "Doing an Experiment." When testing a hypothesis, one conducts an experiment to gather data and evidence that either supports or refutes the hypothesis. This involves designing and carrying out a controlled procedure or study to observe and measure the variables of interest. By doing an experiment, researchers can evaluate the validity of their hypothesis and draw conclusions based on the results obtained.

The formula Ba(N3)2 indicates that there are 2 nitrate (N3) ions present. Each nitrate ion contains 3 oxygen atoms, so there are a total of 6 oxygen atoms in the compound Ba(N3)2.

The innermost electron shell, also known as the first energy level or K shell, can hold a maximum of 2 electrons. This is because the first shell has only one orbital, which can accommodate a maximum of 2 electrons according to the Pauli exclusion principle. Therefore, 2 electrons are needed to fill the innermost electron shell.

Chemistry is the branch of science that focuses on the study of matter. It examines the composition, properties, and interactions of substances, as well as the changes they undergo during chemical reactions. By understanding the behavior of atoms and molecules, chemistry allows us to comprehend the structure and behavior of matter at a fundamental level. Through experimentation and analysis, chemists can develop new materials, medicines, and technologies that improve our daily lives. Therefore, chemistry is the correct answer to the question.

The statement in the question is incorrect. Lithium (Li) is not an alkaline earth metal. It is actually an alkali metal. Alkaline earth metals include elements like calcium, magnesium, and barium. Lithium belongs to the alkali metal group, which also includes elements like sodium and potassium.

An example of an intensive property is color because it does not depend on the amount or size of the substance. Color remains the same regardless of the quantity of the substance present. Intensive properties are characteristics that are independent of the amount of the substance and can be used to identify and describe it.

The electron configuration of an atom represents the arrangement of electrons in its energy levels or orbitals. In the case of Chlorine (Cl), the electron configuration is 1s22s22p63s23p5. This means that Chlorine has two electrons in the first energy level (1s), two electrons in the second energy level (2s), six electrons in the second energy level (2p), two electrons in the third energy level (3s), and five electrons in the third energy level (3p). The electron configuration is written in a specific order based on the Aufbau principle, which states that electrons occupy the lowest energy levels first before filling higher energy levels.

The statement is true because the atomic number of calcium is 20, which represents the number of protons in its nucleus. Therefore, calcium always has 20 protons.

Radium (Ra) has the largest atomic radius among the given elements. Atomic radius refers to the size of an atom, and it is determined by the distance between the nucleus and the outermost electron shell. Radium has more electron shells compared to the other elements, which results in a larger atomic radius. Nitrogen (N), Zinc (Zn), and Tungsten (W) have smaller atomic radii compared to Radium.

The electron configuration given in the question corresponds to Zirconium (Zr). The electron configuration shows the distribution of electrons in the different energy levels and orbitals of an atom. In this case, the configuration indicates that the atom has 2 electrons in the 1s orbital, 2 electrons in the 2s orbital, 6 electrons in the 2p orbital, 2 electrons in the 3s orbital, 6 electrons in the 3p orbital, 2 electrons in the 4s orbital, and 2 electrons in the 3d orbital. This matches the electron configuration of Zirconium (Zr), which has an atomic number of 40.

The electron configuration [Ar]4s23d104p3 represents the element Arsenic (As). This configuration indicates that the element has a noble gas core (Ar) and then fills the 4s, 3d, and 4p orbitals. Arsenic is a metalloid that is commonly used in the production of various chemicals and alloys. It is known for its toxicity and is used in pesticides and wood preservatives.

Cl gained an electron because when an atom gains an electron, it becomes negatively charged. In this case, Cl (chlorine) has changed to Cl- (chloride), indicating that it has gained an electron and now has a negative charge.

Sulfur (S) is the correct answer because it has a mass number of 32. The mass number of an element is the sum of the number of protons and neutrons in its nucleus. Sulfur has 16 protons and 16 neutrons, giving it a mass number of 32. Germanium (Ge), Chlorine (Cl), and Arsenic (As) have different mass numbers and are not the correct answers.

Strontium (Sr) is an element located in group 2 of the periodic table, also known as the alkaline earth metals. Elements in group 2 have 2 valence electrons, which are the electrons in the outermost energy level of an atom. Therefore, a strontium atom has 2 valence electrons.

The mass number of an element refers to the total number of protons and neutrons in its nucleus. In the case of Tin (Sn), the mass number is 119, indicating that the nucleus of a Tin atom contains a total of 119 protons and neutrons.

cobalt and iron are both metals so they would bond metallically

Na+ is not an anion because it has a positive charge. An anion is a negatively charged ion, whereas Na+ is a cation. Cations are formed when an atom loses one or more electrons, resulting in a positive charge. In the case of Na+, sodium has lost one electron, leaving it with a positive charge.

Solutions are defined as homogeneous mixtures. All of the particles are evenly distributed throughout the mixture. Solutions are usually made of liquids but can also be gases, solids, and gases dissolved in liquids.

The correct answer is physical change because making ice cream involves a change in the physical state of the ingredients. The mixture of cream, sugar, and flavorings undergoes a process of freezing, which causes the liquid mixture to solidify and become ice cream. This change does not involve a chemical reaction, as the composition and properties of the ingredients remain the same.

Oxygen-18 is the correct answer because it matches the given criteria of having an atomic mass number of 18 and 8 protons. The atomic mass number is the sum of protons and neutrons in an atom, so if an atom has 8 protons, it must have 10 neutrons to reach an atomic mass number of 18. Oxygen-18 is a stable isotope of oxygen and is commonly used in various scientific studies and medical imaging.

Terbium (Tb) is the correct answer because it is one of the elements in the Lanthanoid series. Lanthanoids are a group of elements that have similar properties and are located in the f-block of the periodic table. They are characterized by the filling of the 4f electron shell. Lead (Pb), Einsteinium (Es), and Potassium (K) are not Lanthanoids.

Noble gases have reached an octet configuration and are more stable as they are than they would be after bonding with any other atoms.

OH- is an ion because it has a charge of -1. Ions are formed when atoms gain or lose electrons, resulting in a positive or negative charge. In the case of OH-, the oxygen atom gains an electron, giving it a charge of -1.

Manganese (Mn) and Gold (Au) are transition metals because they both have partially filled d orbitals in their electron configuration. Transition metals are characterized by their ability to form multiple oxidation states and their tendency to exhibit colorful compounds. Manganese is found in many minerals and is commonly used in steel production. Gold is a precious metal known for its high value and is often used in jewelry and electronic components. Silicon (Si) and Strontium (Sr) are not transition metals because they do not have partially filled d orbitals in their electron configuration.

The mass number of an element is the total number of protons and neutrons in its nucleus. In this case, the element is Tin (Sn), and the mass number is given as 119. This means that the nucleus of Tin contains a total of 119 protons and neutrons combined.

Carbon-14 is an isotope of carbon, which means it has 14 total particles in its nucleus. The number of particles in the nucleus is determined by adding the number of protons and neutrons. Since the atomic number of carbon is 6, it has 6 protons. To find the number of neutrons, subtract the number of protons from the total number of particles in the nucleus. Therefore, Carbon-14 has 14 - 6 = 8 neutrons.

Fluorine is a nonmetal and sodium is a metal. Fluorine needs electrons and sodium wants to give electrons up, so it would be an ionic bond.

Nitrogen and oxygen are both nonmetals making it covalent, but oxygen would have a stronger pull on the shared electrons, meaning it would be polar.

The ionization energy is the energy required to remove an electron from an atom or ion. It generally increases from left to right across a period and decreases from top to bottom within a group on the periodic table. In this case, the elements are arranged in order of increasing ionization energy. Fr (Francium) is the first element because it is in the alkali metal group and has the lowest ionization energy. Hg (Mercury) is next, followed by As (Arsenic), Cl (Chlorine), and F (Fluorine), which has the highest ionization energy due to its small atomic size and strong nuclear charge.

Sublimation is the term that describes the process of a substance changing directly from a solid to a gas, without passing through the liquid phase. This occurs when the substance's vapor pressure exceeds its melting point or when the surrounding pressure is very low. During sublimation, the particles of the solid gain enough energy to break their intermolecular bonds and escape into the gas phase.

Because oxygen is a nonmetal it would form a covalent bond. Because the atoms are identical, they would have the same pull on the shared electrons so it would be a nonpolar bond.

All of the available choices are solutions. The tricky one might have been the gold choice. 14-karat gold is actually made with multiple metals. The metals are mixed in solutions at very high temperatures. When they cool to a solid form, the solid is defined as a solid solution. Most metal alloys begin their lives as solutions.

The ion CO32- is called an anion because it has a negative charge. Anions are formed when atoms gain electrons, resulting in a negatively charged ion. In this case, the CO32- ion is formed when a carbon atom bonds with three oxygen atoms and gains two additional electrons. Therefore, the correct answer is anion.