Chemical Bonds Quiz

PDF page 57: Atoms separated by a great distance cannot link; rather, they must come close enough for the electrons in their valence shells to interact. But do atoms ever actually touch one another? Most physicists would say no, because the negatively charged electrons in their valence shells repel one another. No force within the human body—or anywhere in the natural world—is strong enough to overcome this electrical repulsion. So when you read about atoms linking together or colliding, bear in mind that the atoms are not merging in a physical sense. Instead, atoms link by forming a chemical bond. A bond is a weak or strong electrical attraction that holds atoms in the same vicinity. The new grouping is typically more stable—less likely to react again—than its component atoms were when they were separate. A more or less stable grouping of two or more atoms held together by chemical bonds is called a molecule. The bonded atoms may be of the same element, as in the case of H2, which is called molecular hydrogen or hydrogen gas. When a molecule is made up of two or more atoms of different elements, it is called a chemical compound. Thus, a unit of water, or H2O, is a compound, as is a single molecule of the gas methane, or CH4. Three types of chemical bonds are important in human physiology, because they hold together substances that are used by the body for critical aspects of homeostasis, signaling, and energy production, to name just a few important processes. These are ionic bonds, covalent bonds, and hydrogen bonds.

PDF page 57: Atoms separated by a great distance cannot link; rather, they must come close enough for the electrons in their valence shells to interact. But do atoms ever actually touch one another? Most physicists would say no, because the negatively charged electrons in their valence shells repel one another. No force within the human body—or anywhere in the natural world—is strong enough to overcome this electrical repulsion. So when you read about atoms linking together or colliding, bear in mind that the atoms are not merging in a physical sense. Instead, atoms link by forming a chemical bond. A bond is a weak or strong electrical attraction that holds atoms in the same vicinity. The new grouping is typically more stable—less likely to react again—than its component atoms were when they were separate. A more or less stable grouping of two or more atoms held together by chemical bonds is called a molecule. The bonded atoms may be of the same element, as in the case of H2, which is called molecular hydrogen or hydrogen gas. When a molecule is made up of two or more atoms of different elements, it is called a chemical compound. Thus, a unit of water, or H2O, is a compound, as is a single molecule of the gas methane, or CH4. Three types of chemical bonds are important in human physiology, because they hold together substances that are used by the body for critical aspects of homeostasis, signaling, and energy production, to name just a few important processes. These are ionic bonds, covalent bonds, and hydrogen bonds.

PDF page 57: Atoms separated by a great distance cannot link; rather, they must come close enough for the electrons in their valence shells to interact. But do atoms ever actually touch one another? Most physicists would say no, because the negatively charged electrons in their valence shells repel one another. No force within the human body—or anywhere in the natural world—is strong enough to overcome this electrical repulsion. So when you read about atoms linking together or colliding, bear in mind that the atoms are not merging in a physical sense. Instead, atoms link by forming a chemical bond. A bond is a weak or strong electrical attraction that holds atoms in the same vicinity. The new grouping is typically more stable—less likely to react again—than its component atoms were when they were separate. A more or less stable grouping of two or more atoms held together by chemical bonds is called a molecule. The bonded atoms may be of the same element, as in the case of H2, which is called molecular hydrogen or hydrogen gas. When a molecule is made up of two or more atoms of different elements, it is called a chemical compound. Thus, a unit of water, or H2O, is a compound, as is a single molecule of the gas methane, or CH4. Three types of chemical bonds are important in human physiology, because they hold together substances that are used by the body for critical aspects of homeostasis, signaling, and energy production, to name just a few important processes. These are ionic bonds, covalent bonds, and hydrogen bonds.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 58: Potassium (K), for instance, is an important element in all body cells. Its atomic number is 19. It has just one electron in its valence shell. This characteristic makes potassium highly likely to participate in chemical reactions in which it donates one electron. (It is easier for potassium to donate one electron than to gain seven electrons.) The loss will cause the positive charge of potassium’s protons to be more influential than the negative charge of potassium’s electrons. In other words, the + resulting potassium ion will be slightly positive. A potassium ion is written K , indicating that it has lost a single electron. A positively charged ion is known as a cation. Now consider fluorine (F), a component of bones and teeth. Its atomic number is nine, and it has seven electrons in its valence shell. Thus, it is highly likely to bond with other atoms in such a way that fluorine accepts one electron (it is easier for fluorine to gain one electron than to donate seven electrons). When it does, its electrons will outnumber its protons by – one, and it will have an overall negative charge. The ionized form of fluorine is called fluoride, and is written as F . A negatively charged ion is known as an anion. Atoms that have more than one electron to donate or accept will end up with stronger positive or negative charges. A cation ++ that has donated two electrons has a net charge of +2. Using magnesium (Mg) as an example, this can be written Mg or 2+ Mg . An anion that has accepted two electrons has a net charge of –2. The ionic form of selenium (Se), for example, is 2– typically written Se . The opposite charges of cations and anions exert a moderately strong mutual attraction that keeps the atoms in close proximity forming an ionic bond. An ionic bond is an ongoing, close association between ions of opposite charge. The table salt you sprinkle on your food owes its existence to ionic bonding. As shown in Figure 2.8, sodium commonly donates an + – electron to chlorine, becoming the cation Na . When chlorine accepts the electron, it becomes the chloride anion, Cl . With their opposing charges, these two ions strongly attract each other.

PDF page 59: Water is an essential component of life because it is able to break the ionic bonds in salts to free the ions. In fact, in biological fluids, most individual atoms exist as ions. These dissolved ions produce electrical charges within the body. The behavior of these ions produces the tracings of heart and brain function observed as waves on an electrocardiogram (EKG or ECG) or an electroencephalogram (EEG). The electrical activity that derives from the interactions of the charged ions is why they are also called electrolytes.

PDF page 59: Unlike ionic bonds formed by the attraction between a cation’s positive charge and an anion’s negative charge, molecules formed by a covalent bond share electrons in a mutually stabilizing relationship. Like next-door neighbors whose kids hang out first at one home and then at the other, the atoms do not lose or gain electrons permanently. Instead, the electrons move back and forth between the elements. Because of the close sharing of pairs of electrons (one electron from each of two atoms), covalent bonds are stronger than ionic bonds.

PDF page 59: Unlike ionic bonds formed by the attraction between a cation’s positive charge and an anion’s negative charge, molecules formed by a covalent bond share electrons in a mutually stabilizing relationship. Like next-door neighbors whose kids hang out first at one home and then at the other, the atoms do not lose or gain electrons permanently. Instead, the electrons move back and forth between the elements. Because of the close sharing of pairs of electrons (one electron from each of two atoms), covalent bonds are stronger than ionic bonds.