Chapter 5, Atoms Bonding and the Periodic table
Alloys are generally stronger and less reactive than the pure metals from which they are made.
Alloys are generally what?
reactivity increases from top to bottom
Among Groups 1 and 2, _____________________
No.
Are all molecules containing polar bonds polar?
Yes. Within each crystal, the metal atoms exist as closely packed, positively charged ions. The valence electrons drift among the ions.
Are most metals crystalline solids?
Atoms of the inert gases have 8 valence electrons, except for helium which has two) are stable.
Are the elements in Group 18 stable?
losing their one valence electron
Atoms of the alkali metals which is in group 1 have only one valence electron. what do the atoms do to become chemically stable?
very reactive
Because alkali metals lose thier valence electrons to become chemically stable, what does this make them?
The halogens need a gain of just one more electron that gives these atoms the stable number of 8 valence electrons. As a result, the halogens react easily with other elements whose atoms can give up or share electrons.
Because of the elements in group 17 have 7 valence electrons, what do they need to become stable?
Compared to ionic compounds, molecular compounds generally have ower melting points and boiling points. And unlike ionic compounds, molecular compounds do not conduct electric current when melted or dissolved in water.
Compare the properties of molecular compounds to ionic compounds
Covalent bonds usually form between atoms of nonmetals.
Covalent bonds usually form what?
yes. As a result, the electrons are share unequally.
Do atoms of some elements pull more strongly on shared electrons than do atoms of other elements?
No this is because no charged particles are available to move, so there is no current.
Do most molecular compounds conduct electric current? and why?
yes
Does the pattern formed by the ions remains the same no matter what the size of the crystal?
In carbon dioxide, the oxygen atoms attrct electrons much more strongly than carbon does. So, the bonds between the oxygen and carbon atoms are polar. A carbon dioxide molecule has a straight-line shape. As a result, the 2 oxygen atoms pull with equal strength in opposite directions. The attractions cancel out making the molecule nonpolar.
Explain a carbond dioxide molecule.
A water molecule with its two polar bonds is itself polar. A water molecule has 2 hydrogen atoms at one end and an oxygen atom at the other end. The oxygen atom attracts electrons more strongly than do the hydrogen atoms. As a result, the oxygen end has a slight negative charge and the hydrogen end has a slight positibe charge.
Explain a water molecule
In molecular solids, forces hold the molecules close to one another. But the forces between molecules are much weaker than the forces between ions in an ionic sold. Compared with ionic solds, less heat must be added to molecules solids to separate the molecules and chang the solid to a liquid. That is why most familiar compounds that are liquid or gases at room temperature are molecular compounds.
Explain the forces in the molecular solids
The name o the positive ion comes first, ollowed by the name of the negative ion.
For an ionic compound (chemical formula), which name comes first?
a metal's ability to conduct heat is even more useful if the metal can be bent or hammered into a useful shape.
How can a metal's ability to conduct heat evem be more useful?
Depending on how they are mixed, alloys also retain many of the physical properties of metals.
How can the properties of an alloy differ from those of its individual elements?
The properties of solid metals and their alloys can be explained by the structure of metal atoms and the bonding between those atoms. Because that most metals have 1,2, or 3 valence electrons, metal atoms combine chemically with atoms of other elements, they usually lose valence electrons, becoming positively charged metals ions.
How can the properties of solid metals and their alloys be explained?
Atoms usually react in a way that makes each atom more stable.
How do atoms usually react?
Elements do not easily form compounds when they have 8 valence electrons.
How do elements not easily form compounds?
Ionic compounds form solids by building up repeating patterns of ions.
How do ionic compouns form?
Metal atoms combine in regular patterns in which the valence electrons are free to move atom to atom.
How do metal atoms combine?
Nonmetals can bond to other nonmetals by sharing electrons.
How do nonmetals bond to other nonmetals?
When they gain or share enough electrons to have a set of 8 valence electrons.
How do nonmetals react to become more stable?
lose or share electrons
How do semimetals react to become more stable?
3 to 6
How many valence elctrons do semimetals have?
4 or more valence elctrons
How many valence electrons do nometals have?
how easily its atoms lose valence electrons
How reactive a metal depends on what??
opposite
In an ionic compound, every ion is attracted to ions of __________ charge that surround it?
Ionic bonds usualy form when a metal combines with a nonmetal.
Ionic bonds usually form what?
No, Iron objects rust when they are exposed to air and water.
Is Iron a strong metal that you might think would be good for making tools? why?
Why are metals malleable?
Metals are also malleable, they are able to be rolled into thin sheets, as in aluminum foil, or beaten into complex shapes.
Most nonmetals can even bond with another atom of the same element.
Most nonmetals can even bond with what?
The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms.
The ________ of _________ electrons in an atom of an element determines____________ of that element, including the ways in which the ________________.
The molecules of a molecular compound contain atoms that are convalently bonded.
The molecules of a molecular compound contains atoms that are what?
The number of covalent bonds that a nonmetal can form equals the number of electrons needed to make a total of 8.
The number of covalent bonds that a nonmetal can form equals the number of what?
The unequal sharing of electrons is enough to make the atom with the stronger pull slightly negative and the atom with the weaker pull slightly positive.
The unequal sharing of electrons is enough to make the atom what?
Iron is often alloyed with one or more other elements to make steel. Tools made up of steal are much stronger than iron and resist rust much better.
Then what is tools made out of?
The ions form an orderly, three-dimensional arrangement called a crystal.
What are crystals?
Most metals are flexible and can be reshaped easily. They can be stretched, pushed or compressed into different shapes without breaking.
What are most metals like?
Ions that are made of more than one more atom.
What are polytaomic ions?
Either the number of valence electrons increases to eight (or two in case of hydrogen), or the atom gives up loosely held valence electrons.
What are the one or two things that can happen when two atoms react?
Ionic compounds are hard, brittle solids with high melting points. When melted or dissolved in water, they conduct electric current.
What are the properties of ionic compounds?
An atom's valence electrons are those electrons are that have the highest energy level and are held most loosely.
What are valence electrons?
The "sea of electrons" model of metallic bonding helps explain the malleability, ductility, luster, high electrical conductivity, and high thermal conductivity of solid metals.
What does the "sea of electrons" model of metallic bonding help explin?
The next period begins with atoms having valence electrons with higher energy.
What does the next period begins?
That the elements within a group always have the same number of valence electrons. As a result they have similar properties.
What does this repeating pattern tell you?
its energy ncreases
What happens whe you heat a substance such as table salt?
A positively charged end oppositve a negatively charged end.
What happens when a molecule is considered polar?
it gains a negative charge and becomes a negative ion.
What happens when an atom gains an electron?
It loses a negative charge and becomes a postivie ion.
What happens when an atom loses an electron?
Electrons may be transferred from one atom to another, or they may be shared between the atoms.
What happens when atoms bond?
When ionic compounds form, the ions come together in a way that balances out the charges on the ions. The chemical formula for the compound reflects this balance.
What happens when ionic compounds form?
The bonds between ions are broken. As a result, the ions are free to move about, and the solution conducts current.
What happens when ionic crystals dissolve in water?
They break away from each other
What happens when the ions have enough energy to overcome the attractive forces between them?
A chemical bond is the force of attraction that hold two atoms together as a result of the rearragement of electrons between them.
What is a chemical bond?
The chemical bond formed when two atoms share electrons is called a covalent bond.
What is a covalent bond?
A double bond is when two atoms share two pairs of electrons.
What is a double bond?
An electron dot diagram includes the symbol for the element surrounded by dots. Each dot stands for one valence electron.
What is a electron dot diagram?
A metal's luster is due to its valence electrons.
What is a metal's luster due to?
Each metal ion is held in place by a metallic bond, an attraction between a positive metal ion and the many electrons surrounding it.
What is a metallic bond?
A molecular compound is a compound that is compose of molecules.
What is a molecular compound?
A molecule is a neutral group of atoms joined by covalent bonds.
What is a molecule?
A covalent bond in which electrons are shared equally is a nonpolar bond.
What is a nonpolar bond?
A convalent bond in which electrons are shared unequally is called a polar bond.
What is a polar bond?
A triple bond is in which their atoms share three pairs of electrons.
What is a triple bond?
An alloy is a mixture made up of two or more elements, at least one of which is a metal.
What is an alloy?
Forks and spoons, which can be washed over and over again without rusting. That's because stainless steel, an alloy of iron, carbon, nickel, and chromium does not react with and air and water as iron does.
What is an example of tools made out of steel?
For example, pure gold is thin, but it is soft and easily bent. For that reason, gold jewelry and coins are made of an alloy of gold mixed with a harder element, such as copper or silver. These gold alloys are much harder than pure gold but still retain beauty and shine.
What is an example that explains the properties of an alloy that differs from those of its individual element?
An ion is an atom or group of atoms that has a electric charge.
What is an ion?
Electric current is the flow of charged particles.
What is electric current?
The force that holds atoms together in a covalent bond is the attrction of each atom's nucleus for the shared pair of electrons.
What is the force that holds atoms together in a covalent bond?
the name of a metal
What is the name of the positive ion is usually?
Each element has a specific number of valence electrons, ranging from 1 to 8.
What is the specific number of valence electrons in a specific element?
The negatively charged oxgen ends of the polar water molecules attract the positively charged hydrogen ends of nearby water molecules. These attractions pull water molecules toward each other. in contrast there is little attraction amont nonpolar molecules.
What would you find in a water molecule.
Atoms of most elements are more stable, that is less likely to react when they have 8 valence electrons.
When do atoms of most elements are more stable, that is less likely to react?
Inert gases are unlikely to transfer electrons to other atoms. As a result, inert gases do not react easily with other elements.
Why are in the elements in Group 18 stable?
It is due to the strength of their ionic bonds and the attractions amont all the ions.
Why are many crystals of ionic compounds are hard and brittle?
Because the metal ions move easily, this means that they can be bent easily and pulled into thin strands of wires.
Why are metals ductile?
The ions in the solid crystal are tightly bound to each other and cannot move from place to place. If charged particles cannot move, there is no current.
Why do ions in the solid crystal do not urrent well?
Metals act this way because the positive ions are attracted to the loose electrons all around them rather than to other metal ions. However, the metallic bonds between the ion and the surrounding electrons keep the metal from breaking.
Why do metals act this way?
Their valence electrons are not strongly held.
Why do metals lost electrons easily?
because of differences in attractions between their molecules.
Why do the properties of polar and nonpolar compounds differ?
The ionic crystal metls into a liquid. Because ionic bonds are strong, a lot of energy is needd to break them. As a result ionic compounds have high melting points.
Why ionic crystals have high melting points?
It is places there because it has only one valence electron. However, hydrogen is not considered a metal. It is a reactive element, but its properties differ greatly from those of the alkali metals.
Why is hydrogen located above group 1?
This is because one end of a detergent molecule has nonpolar covalent bonds. The other end includes an ionic bond. The detergent's nonpolar end mixes easily with the oil. Meanwhile, the charged ionic end is attracted to polar water molecules, so the detergent dissolves in water.
You found out that adding detergent helped oil and water to mix. why is this?
soidum has 1 valence electron and chlorine has seven valence electrons. When sodium's valence electron is transferred to chlorine, both atoms become ions. The sodium becomes a positive ion (Na+). The chlorine atom becomes a negative ion (Cl-). Because oppositely charged particles attract, the positive Na+ ion and the negative Cl- ion attract each other.
explain how sodium atoms and chlorine atoms combine to form sodium chloride
Group 1: 1 valence e-, Group 2: 2 valence e-, Group 13: 3 valence e-, Group 14: 4 valence e-, Group 15: 5 valence e-, Group 16: 6 valence e-, Group 17: 7 valence e-, Group 18: 8 valence e-.
how many valence electrons are in the elements of Group1, Group 2, Group 13 to 18?
-ide
if the negative ion is a single elements, the end of its name changes to what?
-ate or -ite
if the negative ion is polyatomic, its name usually ends in what?
decreases left to right across the periodic table
the reactivity of metals ______________.
The periodic table reveals the underlying atomic structure of atoms including the arrangment of the electrons.
what does the periodic table reveals?
A chemical formula is a combination of symbols that shows the ratio of elements in a compound.
what is a chemical formula?
A subscript tells you the ratio of elements in the compound.
what is a subscript?
Water and vegetable oil dont mix. The molecules in vegetable oil are nonpolar and nonpolar molecules have little attraction for polar polar water molecules. On the other hand, the water molecules are attracted more strongly to one another than to the molecules of oil. Thus, water stayes with water, and oil stays with oil.
what is an example explaining why the properties of polar and nonpolar compounds differ.
An ionic bond is the attraction between two oppositiely charged ions.
what is an ionic bond?
A compound that consists of positive ions and negative ions, such as sodium chloride, is called an ionic compound.
what is an ionic compound?
Unequal sharing of electrons causes the bonded atoms to have slight electrical charges.
what is the result of unequal sharing of electrons?
