1.
The elements that make up a compound and the number of atoms of each element in a unit of a compound can be shown in a ______.
Correct Answer
B. Chemical formula
Explanation
A chemical formula is used to represent the elements that make up a compound and the number of atoms of each element in a unit of the compound. It consists of the chemical symbols of the elements and subscripts to indicate the number of atoms of each element. For example, the chemical formula for water is H2O, which shows that there are two hydrogen atoms (H) and one oxygen atom (O) in each molecule of water.
2.
A group of atoms that act together as one charged atom is a ______.
Correct Answer
A. Polyatomic ion
Explanation
A group of atoms that act together as one charged atom is known as a polyatomic ion. Polyatomic ions are formed when multiple atoms bond together and gain or lose electrons to become charged. These ions have a distinct charge and behave as a single unit in chemical reactions. Examples of polyatomic ions include sulfate (SO4^2-), ammonium (NH4+), and carbonate (CO3^2-).
3.
In chemical formulas, the number of atoms in a unit of the compound is shown by numbers called ______.
Correct Answer
D. Subscripts
Explanation
In chemical formulas, the number of atoms in a unit of the compound is shown by numbers called subscripts. Subscripts are written below the line and indicate the number of atoms of each element present in the compound. They are used to balance chemical equations and represent the ratio of atoms in a molecule.
4.
A chemical bond that occurs when atoms share electrons is a(n) ______ bond.
Correct Answer
B. Covalent
Explanation
A covalent bond is formed when atoms share electrons. In this type of bond, the electrons are not transferred from one atom to another, but rather are shared between the atoms involved. This sharing of electrons allows both atoms to achieve a stable electron configuration. Therefore, the correct answer is covalent.
5.
The name given to the number of electrons an atom gains, loses, or shares is the _____.
Correct Answer
C. Oxidation number
Explanation
The oxidation number refers to the number of electrons that an atom gains, loses, or shares in a chemical reaction. It is a measure of the atom's ability to undergo oxidation or reduction. The term "ionic number" does not accurately describe the concept of electron gain, loss, or sharing. The "atomic number" refers to the number of protons in an atom's nucleus, not the number of electrons involved in bonding. "Atomic mass" is a measure of the mass of an atom, and is not directly related to electron behavior.
6.
What is the name of a binary compound made up of lithium and chlorine?
Correct Answer
C. Lithium chloride
Explanation
Lithium chloride is the correct answer because it is the binary compound formed by the combination of lithium and chlorine. In binary compounds, the name of the cation (lithium) is written first, followed by the name of the anion (chloride). Therefore, lithium chloride accurately represents the compound made up of lithium and chlorine.
7.
What kind of chemical bond is formed when electrons are transferred from one atom to another atom?
Correct Answer
A. Ionic
Explanation
When electrons are transferred from one atom to another atom, an ionic bond is formed. In this type of bond, one atom loses electrons (becomes positively charged) while the other atom gains those electrons (becomes negatively charged). The resulting attraction between the positive and negative ions creates a strong bond between the two atoms. This type of bond is typically formed between a metal and a non-metal.
8.
The sum of the oxidation numbers is a neutral compound is always ______.
Correct Answer
B. Zero
Explanation
The sum of the oxidation numbers in a neutral compound is always zero because the total positive oxidation numbers must balance out the total negative oxidation numbers in order for the compound to be neutral. This means that the positive oxidation numbers cancel out the negative oxidation numbers, resulting in a net sum of zero.
9.
Why do the noble gases NOT form compounds readily?
Correct Answer
D. Their outer energy levels are completely filled with electrons.
Explanation
The noble gases do not readily form compounds because their outer energy levels are completely filled with electrons. This means that they have a stable electron configuration and do not need to gain or lose electrons to achieve a stable state. As a result, they have little tendency to react with other elements and form compounds.
10.
What is the name of the compound with the formula NaCl?
Correct Answer
A. Sodium chloride
Explanation
The correct answer is sodium chloride. Sodium chloride is the compound with the chemical formula NaCl. It is commonly known as table salt and is composed of sodium cations (Na+) and chloride anions (Cl-). Sodium chloride is a white crystalline solid that is widely used as a seasoning and preservative in food, as well as in various industrial applications.
11.
How many hydrogen atoms are present in one molecule of ammonium acetate, NH4C2H3O2?
Correct Answer
C. 7
Explanation
Ammonium acetate, NH4C2H3O2, is composed of one ammonium ion (NH4+) and one acetate ion (C2H3O2-). The ammonium ion consists of one nitrogen atom bonded to four hydrogen atoms, so there are four hydrogen atoms in the ammonium ion. The acetate ion consists of two carbon atoms, three hydrogen atoms, and two oxygen atoms. Since there are three hydrogen atoms in the acetate ion, the total number of hydrogen atoms in one molecule of ammonium acetate is seven.
12.
The oxidation number of an atom is shown with a _____.
Correct Answer
C. Superscript
Explanation
The oxidation number of an atom is shown with a superscript. In chemistry, oxidation numbers are assigned to atoms in order to keep track of the electron transfer that occurs during chemical reactions. The oxidation number is indicated by a superscript written above the symbol of the atom. It represents the charge that the atom would have if the shared electrons were assigned to the more electronegative atom in a bond.
13.
What is the total number of atoms in a compound Ca(ClO3)2?
Correct Answer
D. 9
Explanation
The compound Ca(ClO3)2 consists of one calcium atom (Ca), two chlorate ions (ClO3-), and two chlorine atoms (Cl). Each chlorate ion contains one chlorine atom and three oxygen atoms, so two chlorate ions contain a total of two chlorine atoms and six oxygen atoms. Therefore, the compound Ca(ClO3)2 contains one calcium atom, two chlorine atoms, and six oxygen atoms, resulting in a total of nine atoms.
14.
Use the table to answer the following question.
Which of the following is the correct formula for magnesium nitrate?
Correct Answer
C. Mg(NO3)2
Explanation
The correct formula for magnesium nitrate is Mg(NO3)2. This is because the formula represents the compound's composition, where Mg is the symbol for magnesium and (NO3)2 indicates that there are two nitrate ions present. The parentheses are used to show that the nitrate ion is a polyatomic ion composed of one nitrogen atom and three oxygen atoms. The subscript 2 outside the parentheses indicates that there are two nitrate ions in the compound.
15.
Use the table to answer the following question.
What is the charge of the phosphate in K3PO4?
Correct Answer
A. 3-
Explanation
The charge of the phosphate ion in K3PO4 is 3-. This is because the potassium ion (K+) has a charge of 1+ and there are three of them, giving a total charge of 3+. The overall charge of the compound K3PO4 must be neutral, so the phosphate ion must have a charge of 3- to balance out the positive charges of the potassium ions.
16.
Use the table to answer the following question.
How many potassium atoms and how many oxygen atoms are there in a binary compound made from these two elements?
Correct Answer
B. Two potassium and one oxygen
Explanation
The correct answer is "two potassium and one oxygen." This means that the binary compound is made up of two potassium atoms and one oxygen atom.
17.
Use the table to answer the following question.
What is the correct name for K2SO4?
Correct Answer
C. Potassium sulfate
Explanation
The correct name for K2SO4 is potassium sulfate.
18.
Use the table to answer the following question.
What is the correct formula for magnesium oxide?
Correct Answer
A. MgO
Explanation
The correct formula for magnesium oxide is MgO. This is because magnesium has a 2+ charge and oxygen has a 2- charge, so they combine in a 1:1 ratio to form MgO. The other options, MgO2, Mg2O2, and Mg2O, do not follow the correct charge balance and are therefore incorrect.
19.
Use the table to answer the following question.
What is the name of the compound with the formula CaO?
Correct Answer
calcium oxide
Explanation
The compound with the formula CaO is called calcium oxide.
20.
Use the table to answer the following question.
What is the name of the compound with the formula MgCl2?
Correct Answer
magnesium chloride
Explanation
The correct answer is magnesium chloride because the compound with the formula MgCl2 is formed by the combination of one magnesium atom (Mg) and two chlorine atoms (Cl). Therefore, the name of this compound is magnesium chloride.
21.
The properties of a compound are the same as the properties of the elements making up the compound.
Correct Answer
B. False
Explanation
They are "different from" rather than "the same".
22.
Because a water molecule has a slight positive charge at one end and a slight negative charge at the other end, it is a nonpolar molecule.
Correct Answer
B. False
Explanation
It is "polar" rather than "nonpolar".
23.
Molecules are neutral.
Correct Answer
A. True
Explanation
Molecules are neutral because they have an equal number of protons and electrons. Protons have a positive charge, while electrons have a negative charge. These opposite charges balance each other out, resulting in a neutral overall charge for the molecule. Therefore, the statement "Molecules are neutral" is true.
24.
The term anhydrous means without water.
Correct Answer
A. True
Explanation
The term "anhydrous" refers to a substance or compound that does not contain any water molecules. It is derived from the Greek words "an" meaning without and "hydros" meaning water. Therefore, the statement "anhydrous means without water" is true.
25.
Particles formed from the covalent bonding of atoms are called ions.
Correct Answer
B. False
Explanation
They are called "molecules" rather than "ions".
26.
When atoms gain or lose electrons, the charged particles that result are called ions.
Correct Answer
A. True
Explanation
Atoms can gain or lose electrons during a process called ionization. When an atom gains electrons, it becomes negatively charged and is called an anion. On the other hand, when an atom loses electrons, it becomes positively charged and is called a cation. Therefore, the statement that "when atoms gain or lose electrons, the charged particles that result are called ions" is true.
27.
Write the name for the following compound: CaBr2
Correct Answer
calcium bromide
Explanation
The name for the compound CaBr2 is calcium bromide. This is because Ca represents the symbol for calcium, and Br represents the symbol for bromide. The subscript 2 indicates that there are two bromide ions present in the compound. Therefore, the correct name for this compound is calcium bromide.
28.
Write the name for the following compound: CuCl
Correct Answer
copper (I) chloride
Explanation
The compound CuCl is named copper (I) chloride. This is because the copper ion in this compound has a +1 charge, making it a copper (I) ion. The chloride ion has a -1 charge, so it is simply called chloride. Therefore, the name for this compound is copper (I) chloride.
29.
Write the name for the following compound: MgS
Correct Answer
magnesium sulfide
Explanation
The compound MgS is named magnesium sulfide because it consists of one magnesium atom bonded to one sulfur atom. In chemical nomenclature, the name of the cation (Mg) is written first, followed by the name of the anion (S). The suffix "-ide" is added to the name of the anion to indicate that it is a negatively charged ion. Therefore, the correct name for this compound is magnesium sulfide.
30.
Write the formula for the following compound: copper (I) sulfide
*You will not be able to make a subscript. Write in the number where it belongs.
Correct Answer
Cu2S
Explanation
The formula for copper (I) sulfide is Cu2S. This means that the compound consists of two copper atoms bonded to one sulfur atom. The subscript "2" indicates that there are two copper atoms present in the compound.
31.
Write the formula for the following compound: calcium chloride
*You will not be able to make a subscript. Write in the number where it belongs.
Correct Answer
CaCl2
Explanation
The formula for calcium chloride is CaCl2. This means that each molecule of calcium chloride contains one calcium atom (Ca) and two chloride atoms (Cl). The subscript "2" indicates that there are two chloride atoms in each molecule.
32.
Write the formula for the following compound: calcium oxide
Correct Answer
CaO
Explanation
Calcium oxide is represented by the chemical formula CaO. In this compound, one calcium atom (Ca) is bonded to one oxygen atom (O). The formula indicates that there is a one-to-one ratio between calcium and oxygen atoms in calcium oxide. Calcium oxide is commonly known as quicklime and is a white, crystalline solid. It is widely used in various industries, including construction, agriculture, and chemical manufacturing.