ionic bonds

formation of ionic bonds

An ionic bond is the force of attraction that holds together positive and negative ions. It forms when atoms of a metallic element give up electrons to atoms of a nonmetallic element. Figure 7.3 shows how this happens. In row 1 of Figure 7.3, an atom of sodium donates an electron to an atom of chlorine (Cl). By losing an electron, the sodium atom becomes a sodium ion. It now has one less electron than protons, giving it a charge of +1. Positive ions such as sodium are given the same name as the element. The chemical symbol has a plus sign to distinguish the ion from an atom of the element. The symbol for a sodium ion is Na+ . By gaining an electron, the chlorine atom becomes a chloride ion. It now has one more electron than protons, giving it a charge of -1. Negative ions are named by adding the suffix ide to the first part of the element name. The symbol for chloride is Cl . Sodium and chloride ions have equal but opposite charges. Opposites attract, so sodium and chloride ions attract each other. They cling together in a strong ionic bond. You can see this in row 2 of Figure 7.3. Brackets separate the ions in the diagram to show that the ions in the compound do not share electrons. You can see animations of sodium chloride forming at these URLs: http://web.jjay.cuny.edu/~acarpi/NSC/salt.htm

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properties of ionic compounds

The crystal structure of ionic compounds is strong and rigid. It takes a lot of energy to break all those strong ionic bonds. As a result, ionic compounds are solids with high melting and boiling points (see Table 7.2). The rigid crystals are brittle and more likely to break than bend when struck. As a result, ionic crystals tend to shatter. You can learn more about the properties of ionic compounds by watching the video at this URL: MEDIA Click image to the left or use the URL below. URL: Compare the melting and boiling points of these ionic compounds with those of water (0C and 100C), which is not an ionic compound. Ionic Compound Sodium chloride (NaCl) Calcium chloride (CaCl2 ) Barium oxide (BaO) Iron bromide (FeBr3 ) Melting Point (C) 801 772 1923 684 Boiling Point (C) 1413 1935 2000 934 Solid ionic compounds are poor conductors of electricity. The strong bonds between ions lock them into place in the crystal. However, in the liquid state, ionic compounds are good conductors of electricity. Most ionic compounds dissolve easily in water. When they dissolve, they separate into individual ions. The ions can move freely, so they are good conductors of electricity. Dissolved ionic compounds are called electrolytes.

ionic compounds

Ionic compounds contain ions of metals and nonmetals held together by ionic bonds. Ionic compounds do not form molecules. Instead, many positive and negative ions bond together to form a structure called a crystal. You can see an example of a crystal in Figure 7.5. It shows the ionic compound sodium chloride. Positive sodium ions (Na+ ) alternate with negative chloride ions (Cl ). The oppositely charged ions are strongly attracted to each other. Helpful Hints Naming Ionic Compounds Ionic compounds are named for their positive and negative ions. The name of the positive

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energy and ionic bonds

It takes energy to remove valence electrons from an atom. The force of attraction between the negative electrons and positive nucleus must be overcome. The amount of energy needed depends on the element. Less energy is needed to remove just one or a few electrons than many. This explains why sodium and other alkali metals form positive ions so easily. Less energy is also needed to remove electrons from larger atoms in the same group. For example, in group 1, it takes less energy to remove an electron from francium (Fr) at the bottom of the group than from lithium (Li) at the top of the group (see Figure 7.4). In bigger atoms, valence electrons are farther from the nucleus. As a result, the force of attraction between the electrons and nucleus is weaker. What happens when an atom gains an electron and becomes a negative ion? Energy is released. Halogens release the most energy when they form ions. As a result, they are very reactive.

why ionic bonds form

Ionic bonds form only between metals and nonmetals. Metals "want" to give up electrons, and nonmetals "want" to gain electrons. Find sodium (Na) in Figure 7.4. Sodium is an alkali metal in group 1. Like other group 1 elements, it has just one valence electron. If sodium loses that one electron, it will have a full outer energy level. Now find fluorine (F) in Figure 7.4. Fluorine is a halogen in group 17. It has seven valence electrons. If fluorine gains one electron, it will have a full outer energy level. After sodium gives up its valence electron to fluorine, both atoms have a more stable arrangement of electrons.

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uses of ionic compounds

Ionic compounds have many uses. Some are shown in Figure 7.6. Many ionic compounds are used in industry. The human body also needs several ions for good health. Having low levels of the ions can endanger important functions such as heartbeat. Solutions of ionic compounds can be used to restore the ions.

instructional diagrams

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This diagram shows the ionic bonds in lithium fluoride molecule. An ionic bond is the force of attraction that holds together positive and negative ions. The lithium fluorine molecule consists of one lithium atom and one fluorine atom with the chemical formula of LiF. The lithium ion has one more protons than the number of electron thus has the charge of +1. The fluorine ion has one more electron than the number of protons thus has the charge of -1. The lithium ion and fluorine ion have equal but opposite charges so they attract each other. By the attracting force, they form a lithium fluoride molecule.

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The diagram shows an example of ionic bonding. Ionic bonding is a type of chemical bond that occurs between a metallic atom and a nonmetallic atom that join together to form an ionic compound. In the figure, the metallic atom is the sodium atom and the nonmetallic atom is the chlorine atom. During iconic bonding, the metallic atom gives up an electron to the nonmetallic atom. The sodium atom therefore loses an electron while the chlorine atom gains an electron. Because of the electron transfer, each atom now has an unequal number of electrons and protons, thereby becoming an electrically charged ion. An atom that has lost an electron becomes an ion with a positive charge. A positive ion is called a cation. An atom that has gained an electron becomes an ion with a negative charge. A negative ion is called an anion. In short, the sodium atom becomes a sodium cation, whereas the chlorine atom becomes a chloride anion. (Chlorine becomes chloride when it gains an electrical charge.) Because the two ions have opposite electrical charges, they become attracted to each other and bond together, forming the ionic compound sodium chloride.

questions

Ionic compounds form when ions share electrons.

a. true

-->  b. false

When halogens form ions they

a. become positive in charge.

-->  b. become negative in charge.

c. gain two electrons.

d. two of the above

In sodium chloride, sodium loses an electron to chlorine.

-->  a. true

b. false

Which two elements would not form ionic bonds?

-->  a. calcium and lithium

b. calcium and oxygen

c. lithium and oxygen

d. calcium and carbon

Ionic bonds form only between atoms of nonmetals.

a. true

-->  b. false

Energy is released when

a. valence electrons are removed from an atom.

-->  b. valence electrons are gained by an atom.

c. a positive ion forms.

d. two of the above

A sodium ion has a charge of

a. -1

b. -2

-->  c. +1

d. +2

The amount of energy needed to form an ion depends only on the number of valence electrons.

a. true

-->  b. false

Francium has the same number of valence electrons as lithium.

-->  a. true

b. false

In a given metals group of the periodic table, compared with elements closer to the top of the table, elements closer to the bottom

-->  a. have valence electrons that are farther from the nucleus.

b. have valence electrons that are harder to remove from the atom.

c. need more energy to form positive ions.

d. all of the above

Alkali metals release the most energy when they become ions.

a. true

-->  b. false

Salt consists of molecules of sodium and chloride ions.

a. true

-->  b. false

When an atom of iodine becomes an ion, it is named iodide.

-->  a. true

b. false

Ionic compounds are usually liquids at room temperature.

a. true

-->  b. false

Water is an example of an ionic compound.

a. true

-->  b. false

An ionic bond forms when atoms of a nonmetal give up electrons to atoms of a metal.

a. true

-->  b. false

Sodium and chloride ions have equal but opposite charges.

-->  a. true

b. false

Metals need energy in order to become ions.

-->  a. true

b. false

The bonds of crystals are very weak.

a. true

-->  b. false

Solid ionic compounds are good conductors of electricity.

a. true

-->  b. false

dissolved ionic compound

a. ion

b. ionic bond

c. ionic compound

d. crystal

-->  e. electrolyte

f. sodium

g. chloride

unique substance that forms when a metal and a nonmetal combine chemically

a. ion

b. ionic bond

-->  c. ionic compound

d. crystal

e. electrolyte

f. sodium

g. chloride

example of an alkali metal

a. ion

b. ionic bond

c. ionic compound

d. crystal

e. electrolyte

-->  f. sodium

g. chloride

force of attraction that holds together positive and negative ions

a. ion

-->  b. ionic bond

c. ionic compound

d. crystal

e. electrolyte

f. sodium

g. chloride

example of a negative ion

a. ion

b. ionic bond

c. ionic compound

d. crystal

e. electrolyte

f. sodium

-->  g. chloride

charged particle that forms when an atom gains or loses electrons

-->  a. ion

b. ionic bond

c. ionic compound

d. crystal

e. electrolyte

f. sodium

g. chloride

structure that forms when many positive and negative ions bond together

a. ion

b. ionic bond

c. ionic compound

-->  d. crystal

e. electrolyte

f. sodium

g. chloride

When metallic elements become ions they

a. gain electrons.

-->  b. become positively charged.

c. become negatively charged.

d. two of the above

Which two elements could form an ionic compound?

a. carbon and oxygen

b. hydrogen and nitrogen

-->  c. lithium and fluorine

d. boron and neon

Which statement about energy and ionic bonds is true?

a. It takes energy to form a negative ion.

b. Halogens need the most energy to become ions.

-->  c. It takes energy to remove valence electrons from an atom.

d. It takes more energy to gain two electrons than one electron.

Which of the following compounds is not an ionic compound?

a. barium oxide

b. lithium oxide

-->  c. carbon dioxide

d. calcium chloride

Properties of ionic compounds include

a. high melting points.

b. high boiling points.

c. brittleness.

-->  d. all of the above

Ionic compounds are good conductors of electricity when they are

a. shaped into wires.

-->  b. dissolved in water.

c. formed into crystals.

d. made of two metals.

In which of the following elements is the valence electron farthest from the nucleus?

a. lithium (Li)

b. sodium (Na)

c. potassium (K)

-->  d. rubidium (Rb)

diagram questions

question_image

What does a sodium atom and a chlorine atom produce?

-->  a. Sodium Chloride

b. More sodium

c. More chlorine

d. Less sodium

question_image

What are the sodium atom and the chlorine atom forming?

a. sodiom chlorine

b. sodiom chloride

c. sodium clorine

-->  d. sodium chloride

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In which type of bond do atoms share electrons?

-->  a. Covalent Bonds

b. Nonpolar Ionic

c. Ionic

d. Covalent Ionic

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In a covalent bond, what happens to electrons?

-->  a. They are shared.

b. They are created.

c. They are destroyed.

d. They are transferred.

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An ionic bond forms when which atomic particle is given up to another atom?

-->  a. Electron

b. Nucleus

c. Proton

d. Neutron

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How many electrons are shown in this diagram?

a. 5

-->  b. 9

c. 6

d. 4

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If the transfer of electron happens as shown in the diagram below, what will be the charge on the negative ion?

a. 10

b. -10

-->  c. 1

d. -1

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In the diagram, what does the blue and red circles represent?

-->  a. Nucleous

b. Electrons Only

c. Protons Only

d. Neutrons Only

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Which element is the yellow atom?

a. Chlorine

-->  b. Sodium

c. Carbon

d. Natrium

question_image

What does Sodium do to Chlorine?

a. Nothing

-->  b. Give an Electron

c. Take an Electron

d. Share Electrons

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What happens after sodium passed an ion to chlorine?

a. Sodium becomes a negative ion.

b. Both become negative ions.

c. Nothing happens between them.

-->  d. Chlorine becomes a negative ion.

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What is being donated to form the bond?

-->  a. Sodium electron

b. Sodium proton

c. Chlorine proton

d. Chlorine electron

question_image

How many electrons in a sodium ion?

-->  a. 10

b. 75

c. 1

d. 43

question_image

How many Sodium atoms are shown in this diagram?

a. 4

-->  b. 2

c. 5

d. 1

question_image

Which element shared its outside electron?

a. Chloride.

b. Sodium Chloride.

c. Cannot determine.

-->  d. Sodium.

question_image

How many electrons are lost by the Sodium atom?

a. 8

b. 10

-->  c. 1

d. 2

question_image

How many electrons are on the inner level of sodium?

a. 3

b. 8

c. 9

-->  d. 2

question_image

This ionic bond will create what compound?

a. Na+1Cl-1

-->  b. NaCl

c. NACL

d. ClNa

question_image

After transferring an electron to chlorine, what charge does the sodium atom have?

-->  a. Positive

b. Varying

c. Neutral

d. Negative

question_image

How many electrons transferred between elements in this diagram?

a. 3

b. 2

-->  c. 1

d. 4

question_image

What happens after sodium pass its electron to the chlorine?

a. Both elements will separate from each other

b. Sodium will gain a charge and chlorine will lose a charge

-->  c. The compound created will become stable

d. The compound created will explore