Chemistry Practice Final

The symbol Ca+1 represents a calcium ion. Calcium ions have a positive charge of +1, indicating that they have lost one electron. The symbol "Ca" represents the element calcium, and the superscript "+1" indicates the ion's charge. Calcium ions are commonly found in various biological processes and are essential for muscle contraction, nerve function, and bone formation.

In the state of matter known as solid, molecules are closely packed together. This means that the particles of a solid are tightly bound to each other and have a fixed position. The close packing of molecules in a solid gives it a definite shape and volume. Unlike liquids or gases, solids do not flow or easily change their shape because the molecules are held in a rigid structure.

Isotopes are atoms of the same element that have the same number of protons (atomic number) but different numbers of neutrons, resulting in different mass numbers. This means that isotopes have similar chemical properties but different physical properties, such as atomic mass. Isotopes can have varying stability and may undergo radioactive decay.

In the compound Ca3(PO4)2, there are two phosphate (PO4) groups. Each phosphate group contains four oxygen atoms. Therefore, there are a total of 8 oxygen atoms in Ca3(PO4)2.

Digesting food involves a chemical change because during the process of digestion, complex molecules in the food are broken down into simpler molecules through chemical reactions. These reactions involve the action of enzymes and acids in the stomach, which break down proteins, carbohydrates, and fats into smaller molecules that can be absorbed and used by the body for energy and other functions. This transformation of food into nutrients is a chemical change.

The formula Fe2(SO4)3 indicates that there are 2 iron atoms (Fe), 3 sulfate ions (SO4), and a total of 17 atoms in the compound. To calculate the total number of atoms, we multiply the number of atoms in each element by their respective coefficients and add them together: 2(1 iron atom) + 3(1 sulfur atom + 4 oxygen atoms) = 2 + 3(1 + 4) = 2 + 3(5) = 2 + 15 = 17. Therefore, the correct answer is 17.

The chemical formula Fe2(SO3)3 represents the compound iron(III) sulfite. In this compound, two iron (Fe) atoms combine with three sulfate (SO3) groups. The Roman numeral III in parentheses after iron signifies its +3 oxidation state in this compound.

The atomic number of an element represents the number of protons it has. Since the atomic number of uranium (U) is 92, it means that it has 92 protons. The number of electrons in an atom is equal to the number of protons, so uranium also has 92 electrons. The mass number of an element represents the total number of protons and neutrons in its nucleus. In the case of uranium-235, it has a mass number of 235, which means it has 143 neutrons (235 - 92 = 143). Therefore, the correct answer is 92, 92, 143.

The correct answer is atom because an atom is the smallest unit of matter that retains the chemical properties of an element. A sample of an element consists of multiple atoms of the same element. A mixture is a combination of different substances, so it does not apply here. Isotope refers to different forms of an element with varying numbers of neutrons, so it is not the correct answer either. "None of the above" is not the correct answer because an element sample does contain one kind of something, which is atoms of that element.

Neon being very non-reactive is a chemical property because it describes the behavior of the element in chemical reactions. Chemical properties are characteristics that can only be observed when a substance undergoes a chemical change or reaction, such as its reactivity with other substances. In this case, neon's non-reactivity indicates that it does not easily undergo chemical reactions with other elements or compounds, making it a chemical property.

A compound is a substance formed by the chemical combination of two or more elements in definite proportions. In chemistry, a formula is used to represent a compound, indicating the types and numbers of atoms present in the compound. Therefore, the correct answer is "a compound" because a formula is not used to represent just an element or an atom, but rather the combination of elements in a compound.

In a chemical change, the products that are formed are different substances from the starting materials. This is because chemical reactions involve the rearrangement of atoms and bonds, resulting in the formation of new substances with different properties. Therefore, the statement that "the products are different substances from the starting materials" is a valid explanation for a chemical change.

A compound is a pure substance made up of more than one kind of atom. It is formed when atoms of different elements chemically combine in fixed ratios. Compounds have unique properties that are different from the elements they are made of. Therefore, the correct answer is a compound.

The element's most stable ion has a mass of 34 and 18 electrons. The atomic mass of the ion is 34, which is the sum of the number of protons and neutrons in the nucleus. Since the ion has 18 electrons, the number of protons is also 18, as the number of electrons in an atom is equal to the number of protons. Therefore, the element's identity is argon (Ar), which has an atomic number of 18. The number of neutrons can be calculated by subtracting the number of protons (18) from the atomic mass (34), giving us a total of 16 neutrons. Therefore, the correct answer is Ar, 16 neutrons.