Question 1

In the crystal matrix of ordinary salt,the sodium and chlorine are held together by:

Accepted Answer

Sodium and chlorine have opposite charges, causing them to bond through ionic bonds.

Question 2

All atoms tend to fill their outer energy levels with the maximum number of electrons,usually eight.Depending on whether atoms satisfy the octet rule will predict:

Accepted Answer

The octet rule is a fundamental concept in chemistry that predicts the chemical behavior of atoms. Atoms that satisfy the octet rule by filling their outer energy levels with eight electrons tend to be stable and non-reactive, while atoms that do not satisfy the octet rule by having fewer or more than eight electrons in their outer energy levels tend to be reactive and form chemical bonds with other atoms. Therefore, the octet rule is a useful tool for predicting the chemical behavior of atoms.

Question 3

Two oxygen atoms joined to each other by the sharing of two pairs of electrons form a(n):

Accepted Answer

Two oxygen atoms sharing two pairs of electrons form a double covalent bond, in which both atoms share each other's electrons to complete their own outermost energy level. This is the strongest type of covalent bond.

Question 4

Atoms in which the number of electrons does not equal the number of protons are known as:

Accepted Answer

Atoms in which the number of electrons does not equal the number of protons are known as ions. Valences refer to the number of electrons an atom needs to gain or lose to complete its outermost energy level. Isotopes refer to atoms of the same element with different numbers of neutrons. Isomers refer to molecules with the same chemical formula but different structures.

Question 5

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H⁺ ion concentration?

Accepted Answer

The pH scale is logarithmic, meaning a change of 1 pH unit represents a tenfold change in hydrogen ion concentration. Moving from a pH of 7.5 to 5.5 is a decrease of 2 pH units, which means the hydrogen ion concentration increases by 10^2 or 100-fold.

Question 6

Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere.The substance which brought these molecules together to interact is

Accepted Answer

Water is a polar molecule that can dissolve many types of compounds and create an environment for chemical reactions to occur, making it a likely substance for bringing molecules together to interact and potentially form the first living organisms.

Question 7

Because oxygen is more electronegative than hydrogen,the water molecule is:

Accepted Answer

Oxygen's higher electronegativity means it attracts electrons more strongly, creating a partial negative charge near the oxygen atom and a partial positive charge near the hydrogen atoms. This uneven sharing of electrons creates a polarity in the molecule, making it polar (hydrophilic) rather than nonpolar or ionic.

Question 8

Water molecules are attracted to each other due to the opposite charges created by partial charge separations within the molecules.These attractions are called:

Accepted Answer

Water molecules are polar, meaning that they have a partial negative charge on one end and a partial positive charge on the other end. These partial charges create attractions between the molecules known as hydrogen bonds.

Question 9

When water ionizes,it produces equal amounts of hydrogen and hydroxide ions that can reassociate with each other.The pH of water is:

Accepted Answer

The pH of pure water is 7 because it contains an equal concentration of hydrogen ions (H+) and hydroxide ions (OH-), which balances out to a neutral pH of 7 on the pH scale. When water ionizes, it produces an equal concentration of H+ and OH- ions, but this does not change the pH of the water.

Question 10

How many hydrogen bonds can a water molecule form?

Accepted Answer

A water molecule can form up to four hydrogen bonds: two through its hydrogen atoms and two through the lone pairs of electrons on its oxygen atom.

Question 11

Sodium has 11 electrons arranged in three energy levels.In order to become stable,sodium forms an ion with:

Accepted Answer

Sodium has one valence electron in its outermost energy level. By losing this electron, it will have a complete outer energy level like its nearest noble gas neon. This loss of electron will result in the formation of a positively charged ion, which is represented as Na+. Therefore, the best choice is D, which represents a +1 charge.

Question 12

In a chemical analysis of an animal tissue sample,which element would be in the least quantity?

Accepted Answer

Iodine is not a common element found in animal tissues and is only needed in trace amounts for the synthesis of thyroid hormones. Carbon, hydrogen, nitrogen, and oxygen are all major elements found in living organisms and make up a significant portion of biomolecules such as carbohydrates, lipids, proteins, and nucleic acids. Therefore, iodine would be present in the least quantity in a chemical analysis of an animal tissue sample.

Question 13

Regardless of its shape,a given orbital may contain no more than:

Accepted Answer

According to the Pauli exclusion principle, each orbital can hold a maximum of 2 electrons with opposite spin. Therefore, the best choice is D, which states that a given orbital may contain no more than 2 electrons.

Question 14

The area around a nucleus where an electron is most likely to be found is the:

Accepted Answer

The area around a nucleus where an electron is most likely to be found is called an orbital. Energy level refers to the different levels of energy that an electron can occupy, but it does not specify the location of the electron within that energy level. Electrical space and polar space are not scientifically recognized terms.

Question 15

A scientist conducts a procedure that causes nitrogen atoms to gain neutrons.The resulting atoms will be:

Accepted Answer

By gaining neutrons, the nitrogen atoms become isotopes of nitrogen, meaning that they have the same number of protons (and thus the same atomic number) but a different number of neutrons. This does not result in ionization (gain or loss of electrons), and therefore the resulting atoms are not charged. It also does not result in the creation of new elements.

Question 16

Oxygen has an atomic mass of 16 and an atomic number of 8.How many neutrons are present?

Accepted Answer

To calculate the number of neutrons, subtract the atomic number from the atomic mass. So, 16 - 8 = 8. Therefore, there are 8 neutrons present in the oxygen atom.

Question 17

Oxygen-16 is abundant and has 8 protons and 8 neutrons.Oxygen-18 has two extra neutrons.These two forms are:

Accepted Answer

Oxygen-16 and Oxygen-18 are two different isotopes of oxygen which have the same number of protons (8) but differ in the number of neutrons. Therefore, the correct choice is B, oxygen isotopes.

Question 18

Nitrogen has a higher electronegativity than hydrogen.As a result you would expect that ammonia (NH₃)molecules can form ________ with each other.

Accepted Answer

Ammonia (NH3) molecules can form hydrogen bonds with each other because nitrogen is more electronegative than hydrogen, allowing the hydrogen atoms to act as hydrogen bond donors to the lone pairs on nitrogen atoms in other ammonia molecules.

Question 19

Mendeleev found that when he arranged the known elements according to their atomic mass,the entries in the table exhibited a pattern of chemical properties that repeated itself in groups of eight elements.This led to the generalization now known as:

Accepted Answer

The answer of Mendeleev found that when he arranged the...

Question 20

Which element's isotope is commonly used to determine when biological samples such as fossils,were formed?

Accepted Answer

Carbon-14 is a commonly used isotope for radiocarbon dating, which is used to determine the age of organic materials such as fossils.

Quiz 2: The Nature of Molecules and the Properties of Water

In the crystal matrix of ordinary salt,the sodium and chlorine are held together by:

All atoms tend to fill their outer energy levels with the maximum number of electrons,usually eight.Depending on whether atoms satisfy the octet rule will predict:

Two oxygen atoms joined to each other by the sharing of two pairs of electrons form a(n) :

Atoms in which the number of electrons does not equal the number of protons are known as:

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H⁺ ion concentration?

Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere.The substance which brought these molecules together to interact is

Because oxygen is more electronegative than hydrogen,the water molecule is:

Water molecules are attracted to each other due to the opposite charges created by partial charge separations within the molecules.These attractions are called:

When water ionizes,it produces equal amounts of hydrogen and hydroxide ions that can reassociate with each other.The pH of water is:

How many hydrogen bonds can a water molecule form?

Sodium has 11 electrons arranged in three energy levels.In order to become stable,sodium forms an ion with:

In a chemical analysis of an animal tissue sample,which element would be in the least quantity?

Regardless of its shape,a given orbital may contain no more than:

The area around a nucleus where an electron is most likely to be found is the:

A scientist conducts a procedure that causes nitrogen atoms to gain neutrons.The resulting atoms will be:

Oxygen has an atomic mass of 16 and an atomic number of 8.How many neutrons are present?

Oxygen-16 is abundant and has 8 protons and 8 neutrons.Oxygen-18 has two extra neutrons.These two forms are:

Nitrogen has a higher electronegativity than hydrogen.As a result you would expect that ammonia (NH₃) molecules can form ________ with each other.

Mendeleev found that when he arranged the known elements according to their atomic mass,the entries in the table exhibited a pattern of chemical properties that repeated itself in groups of eight elements.This led to the generalization now known as:

Which element's isotope is commonly used to determine when biological samples such as fossils,were formed?

Quiz 2: The Nature of Molecules and the Properties of Water

In the crystal matrix of ordinary salt,the sodium and chlorine are held together by:

All atoms tend to fill their outer energy levels with the maximum number of electrons,usually eight.Depending on whether atoms satisfy the octet rule will predict:

Two oxygen atoms joined to each other by the sharing of two pairs of electrons form a(n) :

Atoms in which the number of electrons does not equal the number of protons are known as:

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H+ ion concentration?

Life is thought to have evolved from complex molecules formed by the interaction of smaller molecules in oceans and the atmosphere.The substance which brought these molecules together to interact is

Because oxygen is more electronegative than hydrogen,the water molecule is:

Water molecules are attracted to each other due to the opposite charges created by partial charge separations within the molecules.These attractions are called:

When water ionizes,it produces equal amounts of hydrogen and hydroxide ions that can reassociate with each other.The pH of water is:

How many hydrogen bonds can a water molecule form?

Sodium has 11 electrons arranged in three energy levels.In order to become stable,sodium forms an ion with:

In a chemical analysis of an animal tissue sample,which element would be in the least quantity?

Regardless of its shape,a given orbital may contain no more than:

The area around a nucleus where an electron is most likely to be found is the:

A scientist conducts a procedure that causes nitrogen atoms to gain neutrons.The resulting atoms will be:

Oxygen has an atomic mass of 16 and an atomic number of 8.How many neutrons are present?

Oxygen-16 is abundant and has 8 protons and 8 neutrons.Oxygen-18 has two extra neutrons.These two forms are:

Nitrogen has a higher electronegativity than hydrogen.As a result you would expect that ammonia (NH3) molecules can form ________ with each other.

Mendeleev found that when he arranged the known elements according to their atomic mass,the entries in the table exhibited a pattern of chemical properties that repeated itself in groups of eight elements.This led to the generalization now known as:

Which element's isotope is commonly used to determine when biological samples such as fossils,were formed?

The pH of your small intestines is around 7.5 and the pH of your large intestine can be 5.5.As substances travel from the small intestines to the large intestine,what would happen to the H⁺ ion concentration?

Nitrogen has a higher electronegativity than hydrogen.As a result you would expect that ammonia (NH₃) molecules can form ________ with each other.